Orthodontic Treatment of Impacted Teeth

The Orthodontic Treatment of Impacted Teeth AD R IA N BECK ER BOS, LOS RCS, 000 Re ps Clinical Asso ciat e Professo r, Depar tment of O rtho dontics, Hebrew Unive rsityHadassah Schoo l of Dental Medici ne, fou nd ed by the Alpha Om ega Fratern ity,

Jerusalem, Israel

MARTIN DUNITZ

CI M.. rtin Dumtz Ltd I99S Fi ~t published in the Unikd Kingd om in 1998 by ~1 .. rtin

Dunitz Ltd

Tbcl.ivcrv House 7-9 Pratt Street t..o ndufl NW I OAE All rights reserved. No pari of th is publica tion milY b..• reproduced , ~tnrt-'d in .1 retrieva l system, o r tra nsmitted, in any form o r by an y means , elect ronic, nwc h.m ic.ll, pho tocopying, roc ...rd ing or o the rwise without the prior pe rmission of the publisher o r in acco rdance wi th ttlt' provisions of th.., Co pyright Acl 19118, or under the• te rms of any licence pcrmitti n~ limited copymg issued by th.., Copyrigh t Licensing Agen '-1', 33-34 Alfred PIaU', London WC IEroP. ,\ CIP catalog ue recor d for

th i~

btxl k is a\'ailable from the British Library

ISBN 1115317 32f! 2

Co mposition t>y w earsct, Boldon, Tyne and Wear Pri nted an d bo und in Singapore

CONTENTS

Preface

vii

1. Gene ral principles related to the d iagnosis an d treatment of impacted teet h __

1

2. Rad iograph ic met hods related to the diagnosis of impacted teeth

13

3. Surgical expos ure of impacted teeth

25

4. Treatmen t strategy

43

5. Maxillary centra l inciso rs 6. Palatally impacted canines

,

53 85

7. Other sing le teeth

151

8. Impacted teet h in the adu lt

179

9. Cleido crania l d ysplasia

199

Index

231

PREFACE

There can be littl e question th at the treatment of impacted teeth h as caught the imagination of many in the den tal profession . The cha llenge has, over the years, been taken up by the general p ractitioner and by a n umber of dental specialis ts, inclu d ing the paedodonttst, the pe riod on tist , the orthodontis t and, most of all, the o ral and max illofacial surgeon . Each of these p ro fessionals has mu ch "i npu t" 10 offer in the resol ution of the im me d iate

problem and each is able to show some fine resu lts. Howeve r, no sing le ind ivid u al on th is

specialist list can completely and successfully treat more than a few of these cases, witho ut the assistance of one or mo re of others of his/her colleagues on that list. Thus, the type of treatment prescribed may depend u po n which of these d enta l specialists sees the patient firs t an d the level of his/her experience with the p roblem in h is / her field. Such treatmen t may involve su rgica l exposu re and packing, it may involve or thodontic space open ing, perhaps auto-transp lantation, or a surgical dentoal veolar se t-down procedure, or even just an abnorma lly angulated prosthetic crown recons tru ctio n . Experience has com e to show tha t the orthodontic /su rgical mo da lity has the potential to achieve the mo st sati sfa cto ry resu lts, in the long term. Despite this, many or thodontists have ignored or ab rogated their respon-

sibility tow ard s the subject o f im pa cted teeth to others, accounting for the popularity of othe r mod alities of treatment. The sub ject ha s become someth ing o f a Cinderella of dentis try. \Vith in the orthodontic /surgica l modality, much room exist s fo r d eba te as to what should be done first and to wh at lengths each of the two spe cialties rep resen ted should go in the zea lous pursuit of its allotte d portion of the proced ure. The literatur e o ffers scant information and guidan ce to resolve these issues, leaving th e practitioner to fen d for him / he rself, wi th a problem th at has ram ifications in several different specialist realms . This boo k di scusses the many aspe cts of impa cted teeth, inclu d ing thei r prevalence, ae tiology, d iagnosis, treatment tim ing , treatment and progn osis. Since these aspects d iffer between incisors and can ines, and betw een these and the other teeth, a separate cha p ter is devoted to eac h. The ma terial presented is based on the find ings of clinica l research that h as been car ried out in Jeru salem by a small grou p of clinicians, over the pa s t 15 years or so, at the Heb rew Uni ve rsity - Hadassah School o f Dental Medicine, fou nd ed by the Alpha O mega Frate rn ity and from the gleanings of clinical experience in the treatmen t of many hund red s of my patients, yo ung and old .

ORTHODONTIC TREATMENT

viII

An overall an d reco m mended approach to the treatment of impacted teeth is presented an d emphasis is placed on the periodontal prognosis of the results. Among the ma ny ot her aspects of this book, the in tention has bee n to propose ide as and p rinciples that ma y be use d to resolve e ven the most d ifficult im pact ions, e m p loying orthod ontic au xiliaries of many different types a nd designs. No ne of these is speci fic to any particu la r orthodo ntic appliance system or trea tmen t "p hilosophy", notwithsta nd in g the a u tho r's own pe rsonal p references, w hich will become ob vious from man y of th e illustra tions. These auxiliaries may be· used w ith equal faci lity in virtually an y a pplia nce system wit h , v h ich the reader may be fluent. The only limitations in the use of these ideas and principles are those im po se d on the reader by h is /her own im agi nation and willi ng nes s to adapt. The o rthodon tic man ufacturers' catalogues are replete wit h the more commonly and routi nely use d attachmen ts, ar chwircs a nd auxilia rics, which Me offered to the p rofession wi th the aim (If strea m lining the busy practice. These cata log ue items h ave not bee n tailored to the demand s of the clinica l issues that are raised in this book. Thes e issu es, by their very natu re, are exceptional, problemat ic a nd often un ique, while occu rri ng alongside and in ad dition to the routine . Among the more common limitations self-imposed by many orthodontists has been the d isturbing tre nd to rely so co mpletely upon the use of p refo rmed an d p re-welded a ttachments that they ha ve forgotte n the arts of weld ing and soldering a nd no longer carry the necessary mo des t equ ipment. Th is then res tricts one's practice to us ing only wh at is a vailab le and sufficiently commonly u sed to make it com mercially w orth while for the manu facturer to p roduce. By conse nting to this unhea lthy s itu at ion, the orthodontist is agreei ng to work w ith "one h and tie d behind his / he r back" a nd tr ea tment results will inevitably suffer. I acknowledge and am g rateful for th e he lp given me by se veral colleagues; in the preparation of thi s manuscript. An e xcellen t p rofessional relationship has been established a nd has withs tood the tes t of time, w ith two se nio r members o f the Department of Ora l

and Max illofacial Surgery a t H ad assah, wi th whom a modus operandi has been developed, in the treatment of our patients. Professor Arye Shteye r. Head of the Depa rtment and, su bse quently, Professor Josh ua Lustmann have educated me in the finer point s of surgical p roced ure an d ca re while, a t the sam e time, ha ve demonstrat ed a res pec t an d under s tand ing of the needs of the or thodontist at the time of su rger y. I am gra tefu l to them for their collabora tion in the wri ting of Ch apte r 3. Dr llana Brin rea d the original manuscript a nd made so me use fu l suggestions, w hich have been included in the te xt. I am gratefu l to Dr Alexander Va rdimon for his comments reg arding the use of magnets and to D r Tom Weinberger for the discussions that we have had regard in g seve ral issues ra ised in the book. My wi fe, Sheil a, read the earlier manuscrip ts an d mad e ma ny importa nt recommenda tions an d corrections. More than a ny one else. sh e e ncour aged me to keep w ri ting d urin g the many months when other a nd more press ing res ponsibilities cou ld ha ve been used as ju stifiable excuses for putting the project as ide. My collea gu es, D r Monica Ba rzel. Dr Ycc heved be n Basse t, Dr Ga bi Engel, D r Doron H are ry. Dr Tom Weinbe rge r, Professor Yerucham Zilbcrman , and my former graduate stud ents Dr Yossi Abed, Dr Dror Eiscnbud. Dr Syl via Geron, Dr Im ma nu el Gillis, Dr Ra ffi Romano a nd D r Nir Sh pack, have provided me w ith several of the illustrations inclu ded he re a nd I am inde bted to the m. [ am g ra tefu l, too, to Ms Alison Ca m pbe ll, Co mmission in g Editor a t Martin Dunitz Publishers and to Dr Joanna Batragel, Te chnical Editor, for their con structive a nd p rofessio nal critiq ue of the manuscrip t, w hich contribu ted so mu ch to its u ltim a te forma t. I also thank Naomi and D udley Rogg, of the British Hernia Centre, for the compu ter an d o ffice facilities that they p laced at m y disposal during my short sabbatical in London, in the latter stages of the prepa ra tion of the w ork for publi cat ion. Perm ission to use illust ra tions from my own ar ticles that were pu blished in va rious

PREFACE

learn ed jou rnals was gra nted by the publishers of those journals or by the owners of the copy right, as follows> Figu re 5.13 was reprinted from Peret z B, Becker A, Cho sak A (1982). The repositioni ng of a traumatically-intruded mature rooted permanent incisor with a removable appliance. [Pcaodont, 6:343-354, with kind permlssion of the Jou rnal of Ped od on tics Inc. Figu res 5,4 & 5.12 were reprinted from Becker A, Stern N, Zelcer Z (Copy right 1976) Utilizat ion of a dil acerated inciso r toot h as its ow n space maintainer. f. Dmt. 4:263·264, with kind permiss ion from Elsevier Science Ltd ., The Boule vard, Langford Lane, Kid lington OX5 1GB, UK. Figures 9.8-9.14

were reprin ted from Becker, A., Shteyer. A, Bimstcin, E. and Lustmnnn, J. (1997), Cleido cranial dys plasia:

part 2 - a Trea tment Pro tocol for the Orthodontic and Su rgical Modality. A m. I. Orthod. Dentojac. Orttiop. 111:173-183, with kind permi ssion o f Mosby-Year Book Inc., SI. Louis, MO, USA. Figure 6.35 was reprinted from Kornh au ser, S., Abed , Y., Ha rary, D. and Becker, A. (1996), The resolu tion of pa lata llyimpacted can ines using pa latal-occlusal force from a buccal auxiliary. A m. /. Orthod. Dentofac. OrthoJ'. 110:528-534, with kind pe r· mission of Mosby-Year Book lnc.. St. Louis, MO, USA.

I am very thankful for their coope ration and for their agreement. Ad rian Becker [crueolein

1 GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH

CONTENTS • Dental age • Assessing dental age • When is a t ooth co nsi dered to be Impacted? • Imp act ed t eeth and loc al space lo s s • Who se problem? • The timi ng of th e surgical intervent ion • Patient motivation and th e orthodo ntic option

In order to und erstand w hat an im pacted toot h is and whether and when it sho uld be treated , it is necessary to first define our perception of normal development of the dentition as a whole and the time frame within whi ch it operates.

DENTAL AGE A patient 's growth and develop men t may be faste r o r slower th an av erage, and we may assess h is or her age in line with this development (Krogman, 1968). Th us a child may be rela tively tall, so tha t his mor p hological age milY be consid ered to be advanced. By studying rad iographs of the p rogress of oss ification of the epiphysea l cartilages of the bones in the han d s of a young patien t (carpal ind ex) and comparing this w ith average da ta val ues for child ren of the same age, we are in a position to assess the child 's skeletal maturity. Similarly, there is a sexual age assessment related to the appearance of primary and second ary sexu al featu res , a mental age assessment (lQ tests ), an assessment for behaviou r and another to measure a child' s sel f-conce pt. These ind ices are used to complement the

chronologie ag e, wh ich is calculated d irectly from th e birth d ate, to give furthe r info rmation regarding a particul ar ch ild 's growth and development. Dent al age is another of these pa rameters, and is a particularl y relevant and importan t assessment, wh ich is used in advisin g p roper orthodontic treatment tim ing. Schou r and Massier (1941), No lla (1960), Moorrce s et al (1962, 1963) and Koyourndjis ky-Kaye et al (1977) have d rawn u p tables and d iag rammatic cha rts of stages of development of the teeth, from initia tion of the calcification p rocess th rou gh to the co mpl etion o f the roo t ap ex of eac h of the teeth, together with the av erage chronolog ie ages at wh ich each s tage occur s. Eru p tion of each of the va riou s groups of tee th is expe cted at a p articul ar tim e but this may be influe nced by local factors, wh ich may cause pn'mature or delayed eruptio n, with a w ide time-span d iscrepancy. For this reason, eruption time is an unreliable method of assessing den tal age. With few excep tions, ma inly related to frank p athology, root development proceed s in a fairly consta nt manner - usually reg ard less of tooth eru ption or the fate of the

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

2

de cidu ou s p redecessor. It therefore follows that the usc of tooth develop ment as the bas is for dental egc assessment, as determined by exa mination of pe riapical or panoram ic Xc ravs, is a far more accurate too l. Thus we may find that a chil d 11-12 years old has four erupted first pe rmanent molars and all the pe rmanent incisors only, wit h deci duous can ines and mo la rs com pleting the erupted den tition. We re the p racti tioner merel y to run to the eruption chart, he wo uld no ll' that at this age all the pe rmane nt canine s

and premolars shoul d have erupted and he would concl ude that the 12 deciduous teeth are over-retained and should be extracted! Howeve r. two possibi lities ex ist in this situation, and the radiog raphs must be studied carefully to distinguish them from each other. In the event that the radiographs show the unerupted permanent canines and p remolars

ha vin g complet ed most of their expected rout length, then the ch ild's d ent al and chronologic ages coincide (Fig. 1.1). The dec id uous tee th have not shed na turally, because of insu fficien t resorption of their roo ts. As s uch , we have to presume tha t they p rovide the imped imen t to the no rm al eruption of the pe rmanent teeth . The ir pe rm an en t successors may then s trictly be defined as having delap..-d eruption. Un der these ci rcu mstances, it would be a logical decision to extract the decid u ou s tee th, on the grou nds that thei r con tinued p resence defines them as overretained. The second possibility is that the radiographs reveal relatively little root d evelopment, corresponding more closel y perhaps to the p icture of the 9-year-old chi ld on the too th development chart (Fig. 1.2). The child's birth certi ficate ma y indicate that he is 12 years of

Figu re 1.1 Advanced root development o f the canines and premO" lars, de finin g thl'b\.' teeth ,IS exhibiting delayed eruption. Extra ction uf the deciduous t"o.'Ih is indicated.

Figure 1.2 An tt -yea r-old patient wi th roo t development defining de n ial age as 9 yea rs. Extra ction is con tra ind ica ted .

GENERAL PRINC IPLES RELATED TOTHE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH

ag e an d this ma y well be su pported by h is bo dy size and d eve lo pmen t an d by h is int ellige nce. Never theless, his de ntition is that of a ch ild 3 ye ars younger, defin ing h is d enta l age at 9 years. Extraction in the se circu ms tances wou ld be the w rong line of treat ment, since it is to be expected tha t the se tee th will shed normally at the ap pro pr iate delltal age, and early extraction may lead to the unde sired seq uelae that are characte ristic of early extraction . performed for any other reason. From this d iscu ssion , we are no w in a positio n to d efine the terms that we shall use th rou ghout this text. The first refers to a retained deciduous tootu. which ha s a pos itive connotation an d which may be d efined as a tooth tha t rem ains in place beyon d its normal sh ed d ing time . ow ing to ab sence or retarded d evelopment of the pe rmanent successor. By contrast, an d with a ne gat ive conno tation, an coer-retained decid uous tooth is one wh ose unerupted pe rmane nt successor exhibits a roo t developmen t in excess of three-qu art ers of its expected fina l length (Fig. 1.3). A perma nent toottt unth lida ycd em ptio" is an uneru pted toot h whose roo t is developed in excess o f this leng th and whose spontaneo us eruption ma y, in time. be expected. A too th tha t is not expec ted to eru pt in a reasonable time in these circumstanc es is termed an

impacted tooth, Den tal age is not assessed \v ith referen ce to a single tooth on ly, s ince some vari ation is found within the differen t groups of teeth. An all-ro und assessment must be made, and on lv the n Gill 01 defin itive de terminatio n be off~red. However, in d oing this, one shou ld be wary of includi ng the maxillary lateral incisor s, th e m andibular second premola rs and the third molars, w hose de velo pm en t is no t always in line wit h that of the rem aining teeth (Ga rn et al, 1% 3; Sofaer, 1970).

ASSESSING DENTAL AGE When study ing fu ll-mouth pe riap ical radi ographs or a panoram ic film, there are seve ral criteria tha t may be used in the estim ation of tooth development. The first radi ogr aph ic

3

Figu re 1.3

The mand ibular left second deciduous molar is retained (extraction co neremdjcated), since the roo t dt>,velopmen t of its su ccessor is ina d eq uate for normal e ruption. The right ma xillary d eciduou s canine. in oonlrast, is overret ained (extra ction advised), SIf\Cl' its long-rooted sor has delayed e ru pti on .

SUCCl.-~

signs of the p resence of a too th are seen shortly after initiation of calcificatio n of the cusp tips . Thereafte r, o ne ma y atte mpt to deline ate the completed crown form ation, variou s degrees of foo l fo rmation (u sually ex pressed in fractions ), through to the fu lly closed roo t ape x. By and large, orthodontictreatment is perfo rmed 0 11 a relative ly older sec tion of the ch ild popul ation , and, as such, the stag es of root (ormati on are u su ally the onlv factor s that remain relevant. The stage of too th developmen t that is easiest to de fine is tha t rela ting to the closure of the roo t apex . For as lon g as the d enta l papilla is di scern ible at the roo t end , the apex is ope n and still develop ing. O nce fully close d, the papi lla d isap p ears an d a contin uous lamina dura is seen to intimately follow the root out line. The accu racy w ith w hich one milY assess fractions of an unm ea surable and merely 'expected ' final root length is far less reliable and much more s ubject to ind ivid ual obse rver variation . Roo t development of the permane nt teet h is comp leted approximately 25 - 3 ye ars after normal eruption (Nella. 1960). This allo ws us to conclude tha t, at the age of 9 yea rs, the

4

THE ORTHODONTIC TREATMENT OF IMPACT ED TEETH

mandi bula r incisors (w hich erupt at age 6) will be the first teeth to exhib it closed apices an d that these will usually be closely followed by the four first permanent molars. At 9.5 years, the mandibular lateral incisors will com plete, while a t 10 and 11 years respectively, the maxillary central and normally developing lateral inciso rs w ill be full y formed. Th is be ing so, when prese nted with a se t of radi ographs, w e may p roceed to assess denial age by follow ing a s im p le line o f in vestigation, w h ich uses the dental age o f 9 yea rs as its starting poi nt and then p rog resses forw ards or re-traces its s te ps bac kwards, depending upon its find ings. If the mandibular cen tral incisor roots a re com plete, w e may presume the pa tient is at leas t 9 years old (de nt al age), and we may then adva nce, chec kin g for closed a pices of firs t mo la rs (9-9.5 years), ma ndi bul ar la teral incisors (9.5 years), max illary cen tral incisors (to years ), normally developing ma xillary lateral inciso rs (11 ye ars ), mand ibu lar cani nes a nd first premola rs (12-13 years), ma xilla ry first p remolars (13-14 yea rs), normally developin g second p re mola rs a nd max illary ca ni nes (14-15 years), an d second molars (15 yea rs).

By this method, we ma y a rr ive a t a tentative d iagnosis for den tal age, on the ba sis of the last too th in this sequence that has a closed a pex (Fig. 1.4). It is no v.., important to relate th e actual development of the remaining teeth in the sequence to their expected development that may be d eri ved from the wall chart o r from tables that ha ve been prese nted in the literature. Th is may then provid e co rroborative evidence in su pport of the dental age determination. Wh en the denta l age is less tha n 9 ye a rs, none of the pe r ma ne nt teeth w ill ha ve comp leted their roo t de velopment, a nd the clin ician will ha ve no choice but to rely on an es timation of d egree of root developmen t, d egree of cro wn completion and, in the w ry young, init ia tion of crown calcif icat ion (Fig. 1.5). This is mo st conveniently done by working backwa rds from the ex pected de velopment a t age 9 ye ar s and compari ng the dental develop ment status of the patient w ith this, beginning w ith the mandibular cen tral inciso rs a nd the first permanent mo la rs. Thus, at d enta l age 6 years, on e wou ld find one-half to two- th ird s root le ng th of these teeth. and thi s could be corroborated by stu dying the d evelopment of the other tee th . At the sa me

Figu re 1.-1

Figure 1.5

Root apices a re closed in all fir«t molars, all mandibu lar and three ma xilla ry incisors, ("'eluding the monilial)' left late ral inciso r.

Xo closed apices. De ntal age assessment 7.5 }'N T'5 .

GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH

time, one sho u ld expec t une ru pted ma xillary central incisors wit h one-half root leng th, mandi bular canines with on e- third roo t leng th, first p remolars with one-qu a rter roo t lengt h, and so on. As pointed ou t earlier, va ria tion occurs, and this may lead to certain apparent contrad iction s. In such cases, elim ina ting the ma xillerv lateral incisors, the mand ib ula r second premolars and the th ird molars w ill usually sim plify the p roce d ure an d contribute to its accu racy , since these teeth are more ind ivid ually va ria ble co mpa red with the res t of the dentition. Ad d ition ally, un usually small teeth, cun iform premolars an d man dibular incisors, and peg-shaped lateral incisors are mos t often to be seen developing very much later (sometimes as much as 3 or 4, years later), and should no t bt> inclu ded in the ov erall estimation. O ne may then present a dete rmination for the den tition as a whole, w ith the added not ation tha t an ind ivid ual too th may have a mu ch lower den tal age. We ma y occasionally examine a I-t-ye ar-old pa tient wh o ha s a co mplete perman en t den tition. including the secon d molars, with the exception that a mand ibu lar second d eciduous mola r is present. The radiograp hs (Fig. 1.6) show the apices of the first molars, cen tral and latera l incisors, ma nd ib ular canines and premolars to be closed , wh ile the maxillary canines and the seco nd mo lars are almost closed . Howeve r, the u neru pt ed ma ndibular

seco nd pr emolar has an o~1l' n root apex and d eve lopment equ ivalent to ab ou t half its eventual length . O n the basis of the information gathered , we may assess the dental age of the den tition as a whole to be 14 yea rs. At the same time, we should ha ve to note tha t the d en tal age of the unerupted second p remola r wa s approximately 10 years. Ha ving mad e th is determi nation, we may now confid ent ly say that the second pr emolar, ind ivid ua lly, d oes no t exhibit delayed eru ption and the deciduou s secon d mo lar is no t overretained, in the terminology used here. Accord ingly, it wou ld not be appropriate to extract the deciduous too th at this time, but to wait at least a furthe r 2 years, at which time the tooth may be expected to shed normally. To summarize th is d iscussion, it is essential to d iffere nt iate be tween fou r d ifferent con ditions th at may exist whe n we encounter a de ntiti on that incl udes certain deci duou s tee th, inco ns istent with the patient' s chronologic age. Becau se the ens uing classification of these con di tion s is treatment o riented, the labelli ng of a patient with in one of these grou pings ind icates the treatment that is req ui red.

2

Figure 1.6 A late-developing left mandibular second premolar. (Courtesy of Dr M Baezel.)

A late-de7.'t'/oJ'ifl~ dentition, The dental age of the pa tien t lags be hind the chr ono logie age, as witn essed radi ogra phica lly by less root forma tio n than is to be expec ted at a given ag e, in the entire d entition. Typ ically, thi s will be evide nt clinically by the continued and sy mmetrical p resence of all the decid uous m olar s and cani nes on each side of each jaw . Extraction o f decidu ou s teeth is contr aindi cated at this time. Go er-retai ned deciduous Ict'/II. The dental age of the pa tien t ma y be posit ively co rrelated wit h th e ch ronolog ie age, bu t the radi ogr aph shows an ind ividu al permanent tooth or tee th with we ll-d evel oped roots, w hich rema in une rupted . Th is tends to be local ized in a single area and may be d ue to an ec topic siti ng of the pe rmane n t tooth bud, which ha s s timula ted the resorp tion o f only a po rtion o f the roo t o f its d ecid uous p redecesso r, bu t

5

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

6

shedd ing has not occurred becau se of the

persistence of the remaining part of the root or of a second and unresorbed root.

3

-t

Neverthe less, the condition ma y occasio nally be fou nd symme trically in a single den ta l ar ch or in both arches. Extraction of the over-reta ined teeth is indica ted. A normal del/ falase , with si/Ig le or multiple late-dt'!.t'lopil/g p CrIIJr1 I1t' lI f leeth. This condi-

tion is com monly found in relation to the maxilla ry late ral incisor and the mandi bula r second p remola r teeth. a nd extraction of the deciduou s p red ecessor is to be a voided. A combination of the abooe. Some times one may see featu res of each of the above three alte rnat ives in a single de ntition.

The im po rtance of inte rpreti ng the d ifferential d iagnosis fo r a gi ven pa tient cannot be overe m phasized, sin ce it ha s fa r-reach ing effects on all th e as pe cts of diagn osis, treat ment planning a nd trea tmen t tim ing for cases wi th impacted teeth .

WHEN IS A TOOTH CONSIDERED TO BE IMPACTED? From the work of Oren (1962 ), we lea rn that under no rmal circumstances a too th erupts w ith a developing roo t a nd wit h a pproxima tely three-qua rte rs of its fin al roo t length . The man dibula r central incisors and first molars ha w ma rg inally less root development and the ma nd ibula r ca n ines an d se cond molars ma rgina lly mo re when they eru p t. We may therefore ta ke this as a d iagnostic bas eline fro m w hich to assess the er up tion of te eth in general. Th us, shou ld an erupted tooth ha ve less root development (Fig. 1.7), it would be a ppro pri a te to label it as prematurely erupted. This will usually be the consequence of ea rly loss of a deciduous too th, pa rticularly one w hose ex traction w as dictated by deep caries, with res ul tan t pe ria pical pa thology. At the opposite e nd of the scale. we find the unerupted tooth that e xhibits a more completely de ve loped roo t. Th e no rmal eruption process of this too th must be p res u med to

ha ve been imped ed by on e of several actiologic possibilities . Th ese in clud e such factors as a failure of resorption of the roo ts of a d ecid uous too th, an ab normal e ruptive pa th, a supe rn u me ra ry too th, d ental crow d in g or a d isturbance in the e ru pti on mechan ism o f the too th. Howeve r, obstruc tion may also res u lt fro m a thickened post -ext raction or po s ttr auma repair o f the mucosa (Figs 1.8<1, b). No t in freque ntly, and particular ly in the mandibular premolar region, there may be a h istory of ve ry ea rly extraction of one or bo th decid uous mola rs. De layed or no n-e ru ption of the premolars will occur, owin g to a thic kened mucosa over lying the tee th . It may be possible to pa lp at e these teeth, their d istin ct ou tline being clearly seen bu lging the gum for a pe riod of year or more, although e ru ptio n may no t occur.

IMPACTED TEETH AND LOCAL SPACE LOSS A time lapse ex ists between th e pe rformance of a su rgical procedure to remove the ca use of a n impaction and the full eru ption of th e im pa cted tooth into its p lace in the dental a rch. The extent of th is time spa n is de pe n-

Figure 1.7 The left mandibular premolars are prem atu re ly eru pted. ....ith insufficien t root d...vclo pment.

GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH

(.)

(b)

Figu n " 1.8

(a) Th~· righ t mand ib ular second premolar was extracted at age 8.5 y l',lfS. (b) Seen ill age 11. the rool o f the unerupted firsl premolar is alm ost com pleted .

dant on severa l factors, such as the initial d istance between the too th and the occlusa l plane, the stage of the de velop ment of the particular tooth, the age of the pati ent, andthe manne r in which hard and soft tissue may be laid d own in the healing wound . During this lime period, therefore, local ch anges in the eru pted den tition may occur as a resu lt of the break in the integrity o f the d en tal arc h caused by the surgical proced ure, such as space loss and tipping of the adja cent erup ted

teeth. Th is inte rvention is no less suscep tible to the d riftin g of neigh bou ring teeth th an is any other factor that may prod uce inte rp roximal loss of dental tissue. With an od ontom e or su pernumerary tooth in the pat h o f an u neru pted permanen t tooth, vertical (and sometimes mesial or distal or buccal or lingual) d isplacement of the permanent tooth is likely to be consider able. It wo uld be conven ient if the removal of the space-occupying body cou ld be performed, leaving the deciduou s tee th intact, since the deci duou s tooth would mainta in arch integrity d uri ng the extended period of time needed for the permanent tooth to eru pt nor maUy. Unfortunate ly. o ften, in orde r to gain access to perform the desi red surgery. one or more deciduous teeth need to be extracted. Thi s being so. and h avin g regard for the long distance tha t the di splaced permanent tooth has to tra vel. space maintenance should be rega rded as esse ntial in most cases. It sho uld be the first or thodontic procedure to be considered in these cases and it sho uld be ret ained u ntil full eruption has occurred. Impacted teeth are often associated with a lack of space in the im med iate area. This is frequentl y due to the d rifting of ad jacen t teeth, alth ough crowd ing of the dentition in genera l may be the p rime cau se. In such cases, the spon taneo us eruption of an impacted tooth is unlikely to occur unless adequate or, p referab ly, excessive space is provid ed. It wo u ld be convenient if the excision of the associa ted pathologic entity coul d be com fortab ly delayed un til thi s time, to bri ng about the desire d eruption and to permit this correc tive treatment to be attempted when the root developmen t of the unerup ted tooth is ade qu ate. However, the su rgeon will insist on removi ng most forms of pathology as soon as a tentative d iagnosis is reached, in order to obta in exami nable biopsy ma terial for the establishment of a definitive diagnosis. Odontomes and su pernumera ry tee th aTC gen era lly conside red to be exceptions to th is ru le, and the tim ing o f their removal may be mo re leisu rely cons ide red.

7

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

8

WHOSE PROBLEM? Patients do not go to their den tist com plaining o f an im pa cted too th. They are freq uently unaware tha t th is abnormality exists, since there is no pain, d iscomfort or swelling. Neither is it obvious to the layman that there is a miss ing too th, since the decid uous pred ecessor is usu ally reta ined. The vas t majority of impacted teeth come to light by cha nce, in rou tine dent al exa mina tion, and are not the result of a patient' s d irect complaint. As a general rule, it is the pa edodontis t or general den tal p ractitioner who, du ring a routine den tal examination, discove rs and records the existence of an ov er-retai ned de ciduous too th . A periap ical rad iograp h will then confirm the d iagnosis. There are two p rincipal excep tions w here an ab no rmal appearance may be the reason why the patient seeks pr ofession al advice. The first usu ally' brings the patien t to the office at the age of 8-10 years, when a single maxilla ry central incisor will have eru pt ed a yea r or so earlier and the pa ren t points ou t that the erup ting lateral inciso r of the oppo-site side has no t left enough s pace for the expected eruption of the second cen tral incisor (Fig. 1.9). Often, the deci duous cen tral incisor is retained . In this situation, the p aren t has recognized abnormality, bu t w ill not generally have the technical u nderstand ing to suggest the possibility of impaction o f the unerupted central incisor .

Figure 1.9

Une rup ted right max il1
The seco nd exception occu rs w ith a 14--15yea r-old patient who req uests the restorati on of an unsightly cariou s lesion on a retained maxillary deci d uous canine. Gene rally speaking. the pati en t will be una ware tha t this is not a permanent tooth, and it will req uire suitable professional advice to point ou t that restoration is probably no t the appropriate line of treatm en t, rat her extraction and the reso lut ion of the impaction of the pe rmanent canine. A very s mall percentage of cases ma y be see n initially by their genera l denta l practitioner beca use of symptoms related to relatively rare complications of im pacted teeth . Am ong these symptom s ar c mob ility or migration of ad jacent teet h (d ue to roo t resorp tion), pa in less bony expansion (dentigerous or radicular cys t ), or perh ap s p ain and I or discharge (in fected cyst, w ith commun ication to the oral cavity) (Shafer et al. 1983 ). In itially, the p ractition er should ascertain whet her there is a go od chance that resolu tion w ill be spon taneo us, on ce the aetiologic factor has bee n removed, or whether active appli ance therapy w ill be needed . To be in a position to d o this, the exact position , long-axis angulation and rot ational status of the tooth have to be accurately visualized and an assessment of space in the arch must be mad e. Followi ng this initial assessment, the pedodontist or general de ntal p ract itio ner now has to decid e who shou ld treat the p roblem. Ma ny general p ractitioners will p refer not to accept responsibility for the case, and w i11 refer the patient to an oral and maxillofacial surgeo n, on the basis that surgery will be needed. Many surgeons will agr ee that the pr oblem is essen tially surgical in na ture, and will proceed to remove retai ne d deciduous teeth, clear away othe r possible aettolo gtc factor s, su ch as supernumerary teeth, odontomes, cys ts an d tumou rs, and will also expose the impacted pe rmanen t too th . If the im pacted too th is buccally located, the su rgical flap may be apica lly repositioned, to prevent primary closu re and to ma intai n subsequent visua l contact w ith the im pacted too th after healing h as occurred . This will have the effect of en couraging eruption in

GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH

ma ny cases. Un til hea ling (by ' second ary inte ntion' ) has occu r red , the wound will usually be packed with iod oform gauze impregna ted with Whitehead 's va rn ish, over a pe riod of a few weeks. Ca reful placem ent an d wed ging o f th e pack between an impacted tooth and its neighbour is used by surgeons to he lp free th e tooth to erupt na tu rally, wh en the pack is later removed . Of ten, in more di fficult impactions, wider su rgical exposure is undertaken, in clud ing fai rly radical bone resection, both around the crown and d own to the C El, w ith complete rem oval of the dental follicle. Following a period of many months and (for some more aw kw ard ly positio ned teeth ) sometimes exte nd ing int o years, the su rge on will usually the n follow up the spontaneous eruption of the impacted tooth until it reaches the occlus al leve l. If, at that tim e, alignment is poor or the too th still ha s not eru pted, the patient w ill be referred to the orthod ontis t. The paed od on tis t or ge ne ral dental practitioner may alternative ly and preferably refer the pat ien t di rectly to an orthod ontis t. Certainl y, the orthod on tist cann ot d irectly influence the position of the im pacted tooth until appropriate access ha s been p rovided su rgically and an attachment has bee n placed on the tooth. Nevertheless, with proper planning and mana gement , inclu d ing the refer ral for surgical exposu re at th e appropriate stage in the treat me nt, a much high er level of quality care may be p rovided and in a very mu ch shorter tim e frame . This will be d iscussed in the en suing chapters of this boo k.

THE TIMING OF THE SURG ICAL INTERVENTION From the above d iscussion, we see th at the tim ing and nature of the s u rgica l p rocedure are determined by the d eg ree of developmen t of the teeth concerned at the time of initial d iag nos is. At an early stag e, a radiographic su rvey of a very yo ung chil d may reveal pa tholog y, s uch as a su pe rn u merary too th, an odontome , a cys t or benign tu mour , that ap pears like ly to preven t

Figu re 1.10 A midline supern um e ra ry tooth (rnesiodens] discovered in routine periapica l radiograph ic view of the ma xillary incisor a rea.

the no rmal and spon taneous eruption of a neighb ouri ng tooth . At this s tage, from every point of view, it wou ld be inap prop riate to expose the crown of an im matu re too th. In the first place, one would no t wa n t to en courage the toot h to erupt before an adequa te (half to two-t hirds ) root len gth h ad been p roduced . Secondly , at this early stage of its development. the too th cannot be consid ered as impacted , and, given time and freed om to manoeuvre, will probab ly eru pt by itself. Early exposure risks the possibility o f d amage to the crown and to the subsequen t root development of the tooth . Nevertheless, with the d isco very of the pathological con dition (Fig. 1.10), the pot en tial for impaction exists, an d leaving the cond ition untreated will worsen the prognos is. Acco rd ingly, rem oval of the pa tho logical en tity, withou t d istur bing the ad jacen t pe rmanent teeth o r the ir follicular cry p ts, should be the aim of an y treatment at that time. It ma y then reasonably be expected that normal development and erup tion w ill occu r in the fullness of time. Wh ils t this is an obviou sly desi rable co urse of action , access to the targeted area may be th warted by the presence and closeness of adja cent developing st ructu res, and delay may still be advised .

9

10

_ _ _ _ _ _ __

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH _ _"-'----'-'-C----"----=---=--'--------=--=::..--=..'-

Fig u re 1.11

Thl' p,lO<J ra mic rad iugrap h shows e rup ted maxillar y lat e ral incisors an d over -retained d.'cid" o us ..ental incisors. TI1<.' une rupt ed cen tral incisors may be seen su periorly to the two uneru pted supernumerary teet h . (Co urtesy of

Dr I Gi 11i~. )

The second scenario occurs when the cond ition is only d isco vered much later . In th is case (Fig. 1.11). the permanent tee th may justifiably be defined as imp acted, and the aims of s urgical treatme nt become twofo ld: first, to elim ina te the pathology, and then to create op timal cond ition s for the erup tion of the permanent tooth, which is alread y lat e. Th is will u sua lly involve exposure of the crown of the too th. For man y teeth , giv en adequa te sp ace in the dental arch an d little or no disp lacement of the impacted toot h, spon tan eo us eruption may be expected (Dibiase, 1971; Mitchell and Bennett. 1992). As w e sha ll see in subsequent chapters, there arc several situ-

ations and tooth types where this may not occur, o r it may no t occur in a reasonable time fra me, often because of severe di sp lace-ment o f the affected too th . Fo r these cases, the natural erup tive potential of the tooth is s up plemented and, if nece ssary, diver ted mech an ically, wit h the use of an orthodontic app liance.

PATIENT MOT IVATION AND THE ORTHODONTIC OPTION Angl e's Class II ma locclus ion is present in between one- fifth and one-qua rter of the child

po pu lation in most countries of the western world (Massier and Fran kel, 1951; Brin et al,

1986). However, even a cursory analysis of the pa tient load of an y give n or thodontic p ractice will rev eal a round three-quar ters of the pa tients being treated for this ma locclusion. The reas on for this has to do wi th the fact that a pa tien t' s ap pearance is adversel y affected to a grea ter exten t by this condition than by most oth ers. In other word s, ap pearance plays an inordina tely large part in the initiative an d motivati on on the part of the paren t of a you ng pa tien t to see k treatmen t. A signi ficant sectio n of the remaining q uarter of the pati ents in this hypothetical orthodontic p ractice are being treated for various less unsightly con ditions (crowding, single ectopic teeth, ope n bites or class 3 relationships). Thi s leaves on ly a few pa tien ts in this practice sample who have been refe rred fo r strictly hea lth reasons, which may no t be obvious to the pa tient. Appearance is not a problem for th is small gro up of p atie n ts, wh o will have ag reed to orthod on tic treatment on ly after moti vation has been evoked by the carefu l and persu asive ex pla nati ons of a dentist, o rthod ont ist, pe riodontis t, p rosthodontist or o ral surgeon, regarding the ills that are othe rwise likely to befall them and their dentitions. Most im pactions arc symptomless, and, as ide from maxillary central incisors, do not us ua lly present an ob vious ab norma l appearance. Acco rd ingly, mo tiva tion for treatment in these cases is m in ima l, and much time has

GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH

to be spent with the patien t before he or she agrees to trea tme n t. The s tory d oes no t end there, s ince these pa tien ts ma y often require pe riodic ' pep talks' to ma intain their level of coo peration and the ir res ol ve to co mplete the trea tment. Many of them w ill no t main tain the required sta nda rd of oral hygiene, and, while it is d ifficu lt to jus tify continuing treatment in these circumsta nces i ~ is just as d ifficul t to rem ove applian ..o.:'~ rro m a patient in the mid d le of treatme n t, whe n im pacted teeth have bee n pa rtially erupted and large spaces are presen t in the dental arch. For these rea sons. wh ile ambitiou s and innovative treatment p lan s may be suggested , it is essential to take the moti vation factor into acco unt before advis ing lengthy an d com plicated tr eatmen t, since the risk of non-completion may be high.

Koy ou md jisky-Ka ye E, Ba res M, Gro ve r NB (1977) Stages in the emerge nce of the dent i-

tion : an im proved classi fication and its applicat ion to Israeli children. Growth 41: 285--96. Krogm an WM (1968) Bio log ical tim ing and the den to factal com plex . J Dent Chil d 35: 175-85.

Massier M, Frankel JM (1951) Preva len ce of m alocclus ion in child ren aged 14-18 yes. A m J

Ortnod 37: 75 1-60 Mitchell L, Bennett TG (1992) Su pe rn u me rary teeth caus ing delay ed eru ption - a retrospective st udy. Br J Ort}IOO 19: 41-6. Moo rrees CFA, Fanning EA, O ren A-M, Leb ret L (1962) The timing of orthodontic trea tment in relation to too th form ation . Trans Eflr Ortnoa Soc 38 : 1- 14.

REFERENCES Brin I, Becker A, Shal hav M (1986) Position of the maxillary permanent can ine in relation to anomalous or miss ing lateral incisors: a population st udy. Ellr / Orthod 8: 12-1 6.

Di Hi,l SC DD (197 1) The effects of variations in tooth morpholog y and position on eru ption . Dellt Pmct Dent Rec 22: 95-108. Gam SM, Lewis AB, Vicinus JH (1963) Third molar po lym or phism and its s ignificance to denta l genetics. J Delli Rt'S 42: 1344-63. Gran A·M (1962) Pred iction of tooth emergence. J DCllt Res 41: 573-85.

Moorree s C FA, Fann ing EA, Hunt EE Jr (1963) Age va ria tion of for ma tion stages for te n pe rma nent teeth. J Dellt Res 42 : 1490-502. Nella CM (1960 ) The development of pe rmanent teeth. / Dent Child 27: 254- 66 .

Schou r I, Messl e r M (1941) The dev elopment of the hu man d en tition . J Alii Dent Assoc 28: 1153-60.

Shafer WG, Hinc MK. Levy BM (1983) A Texbook of Oral Pathology, 4th ed n. WB Sau nders, Philad elph ia. Sofaer JA (1970) Dental morp holog ic variation and the Hardy Wei nberg law . J Dellt Res 49(Sup pl), 1505.

11

2 RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH

CONTENTS • Qual itative rad iography • CT scann ing

It is not the purpose of this chap ter to present

a complete manu al on dental radio gra phy, but rat her 10 concisely highlight those technique s an d meth od s tha t are usefu l in the clinical setting, as it pe rtains to im pacted teeth. The me thods offered have two ma in aims (Sewa rd , 1968; Hun ter, 1981). The firs t relates to the fu rn ishing of qu ali tat ive informa tion regard ing no rmal and abnormal condi tion s that ma y be associated w ith unerupted teeth . Thu s the d ifferent ways of radiologically displ ay ing and recognizing patholog ical entities, such as su pernu me rary teeth, enl arged eruption follicles, odon tomes, root resorption and other patholog ical en tities, arc dis cus sed and compared . The second aim is to describe the var ious radiological techniqu es that the clin ician may find helpful in accurately pinpointing the position of a clinically invisible, unerupted too th . The relative merits of the se techniques ar e di scussed, and ind ications for their use arc suggest ed in relation to the di fferent gro ups o f teeth involved .

• Th ree-d imensional diagnosis of to oth po sit ion

Q UALITATIVE RADIOG RAPHY

Periap ica l radiographs The first, simplest and most inform at ive X-ray film is the pe riapical vie w. This view is oriented to pass through the m inimum of su rrounding tissue. in order to give accu racy an d qu ality of resolut ion . It is generally aimed to be perpendicular to an imaginary plane bisecting the angle between the lon g axis of an erupted tooth and th e film plane, to produce the minimum of distortion. The penaptcal film is designed to view the tooth itself from the angle of best advantage, without any relation to its position in space. From this film, it w ill be immediately obvious if there is an impacted tooth and if its stage of d evelop ment is sim ila r to that of its erupted an timere, w ith at least two-thirds of its root length . The presence and size of a follicle will be obvious, and it will be possible to asce rtain crown or roo t resorp tion, roo t pattern and integrity . The p resence and d escription of hard tissue obstruction w ill be evident, allowing the observer to d istinguish connate, in risiform and b arrel-shaped su pe rn u meraries, and odontomes o f the comp lex or

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ...::.::.:::...::.:==:::...:.==::.::-=..:==::::..:.:::.::.:

14

com pou nd com posite types. Simila rly, it will show soft tissue lesions, such as cysts. The grea t clarity offered by the view is su perior to that o f othe r views, and it should always be used as the init ial film of a suspected impacted toot h in a rad iographic exam ination. As with any radiogra phic film, however, the periapical view is only twa-di mensional, and gives no information in the b ucca- lingual plane; overlap ping structu res cannot be d ifferentiated as to which is lingual an d which buccal. For this film to give the most advan tageous view of the tee th in the maxillary arch and in the mandib ula r an terior segment, the central ray of the periapical view is obliqu e, and w ill vary between 20° an d 55° to the occlusa l plane (Mason, 1982), depend ing upon the region to be x -rayed. Given this oblique direction, any attempt to estimate the height of the tooth o r its bucca-lin gual orientation. without ad di tional info rmation, must fail. When pe rform ing pe riapical radi ography on the poste rior teeth in the mandibular arch, however, the most ad van tageou s direction has the centra l ray very close to the horizontal, and, as such, also offers a true lateral view of these teeth. Thu s not on ly will the observer see the most precise de tail of the too th and its surrou nd ing tissues, bu t it will also be po ssible to accu rate ly assess its heigh t in the jaw.

Occlusal radiogra phs Mandibular arch

In the mandi bu lar arch, this view is properly executed by tipp ing the patient's head backwards an d po intin g the X-ray tube at rightang les to a film, held between the teeth, in the occlusal plane (Fig. 2.1). In the low er canine / pre molar region, the occlus al view is a 'true' occlusal view an d sho uld de pict all the posterior standing teeth in cross-section. As su ch, it shou ld also provide bu cco-lingual position al in formation on the tooth and an y associated structu res in a plan e at righ t ang les to tha t seen on the periapical film. Because of the thickness of bone trave rsed, de tail is mu ch po orer, u nless there is expansion du e to

Figu re 2.1 Taking a true occlusal view of the lowe r jaw: for the canine / premolar region and for the incisor region.

a large cyst or bucca-lin gually displaced tooth. In orde r to p rodu ce a true occlusal view in the anterior reg ion of the mandibu lar arch (Fig. 2.1), the head will need to be tip ped back further and the tub e po inted at the sy mp hysis menti, at an angle of 110° to the horizon tal, in line with the long axes of the incisor teeth. To achieve the same for the molar teeth, the 90° angle to the horizontal will need to be augmen ted by a 15° med ial tilt of the tube, to compensate for the characteristic sligh t lingua l tip ping of these teeth (Mason, 1982). Maxillary arch

Maxillary anterior occlusal. In the m axillary arch, the no se and fo rehead interfer e w ith the positioning of the x -ray tube, close to the area to be viewed . The best that can be achieved by positioning the tube close to the face is an an terior maxillary occlusal view of the teet h, wh ich is perhap s bet ter described as a high or steeply-ang led pe riapical view (Fig. 2.2). The view w ill 'shorten' the actual length of the roots, bu t it w ill be a far cry fro m the crosssectional view that is so easy to achieve in the mandibular arch. Since the cen tral ray passes

RADIOG RAPHIC METHODS RELATED TO THE DIAG NO SIS OF IMPACTED TEETH

Vertex occluuJ ( 110" \ to occluu l plane)

Anter ior occluul (60" to ccchrsa l plane)

Periapical

\

\

!JiJ

!J"

~

Occtosat "

plane

Figu re 2.2 A di ag ram showi ng inciso r inclin atio n, film pos ition a nd cen tral X-ra y beam, d iffere ntiating the periapical " le w, the a n lt'rior (ob liqu e) occlusal vie w and the true verte x occlusal views.

through less thickness of bone, detail is usually good, alt hough no t as clear as w ith the per iapica l view . True (i xrtex) occlusal. A true occlusal view of the anterior maxilla is a view in which the centra l ray of the X-ray beam ru ns pa rallel to the long axis of the centra l incisor s (Fig. 2.2). This is only possible when the cone is p laced ove r the vertex of the skull, to p rodu ce the vertex occlusa l film. Since the beam h as to travel a great d istance through the cran ium and its con tents, the base of the sk ull and the maxilla, there is a conside rable loss in clarity. Recently, an excellen t method of p rod ucing this view extra-orally ha s been described (Dog. 1994). In order to avoid the need for a very long exposu re, a fast film sh ou ld be used in a cassette with intensifying screens. For these reason s, the method is no t popular. Nevertheless, in this view (Fig. 2.3), all the

Figure 2.3

A trw.' vertex occlusal film usi ng On g' s pmjl'rtion, sho winll) two palatal ca nines. The right canine is ChlSl' to the arch and almost vertical. The cro wn of the Il'fl ca n ine reaches the midlin e sut ure, while the Toot a pex is close to the line of the a rch.

ante rior teeth will be seen in their crosssection al view as sm all circles with a tiny concentric circle in the cen tre, denoting the pulp chamber. No information is available regarding the relative height of the object in the alveolus, and it certainly cannot be used for fine detail. A single tooth that is palatal to the line of the arch will ap pear wit hin th is arc of sma ll circles. If the too th is at an ang le, not parallel to its neighbours, it will show up inits elliptical, ob lique cross-section, repres enting a tilted long nxis. If th e tooth is horizon tal across the palate, its full length will be obvious on th is view, togethe r w ith the exact mesio-d istal and bucco-lingual or ientation of both the root an d the cro wn, in the hor izontal plane (Fig. 2.3). Th e di fferen ce between the two types of occlusal film may not seem to be very great, but it sho uld be app reciate d that, from the van tage po int of an anter ior occlusal film, the an terior tee th will be fores hor tened but will still have app reciable length. In thi s situ ation, a high and mesially placed labial canine could give precisely the same picture as a low and mesially p laced palatal canine. Th is cou ld not happen in a vert ex occlusal projection.

15

16

THE ORTHODONTIC TREA TMENT OF IMPACTED TEETH

(a)

Ibl

Ie)

[dl

[e)

Fig u re 2.-1

(a) The periapical v iew shows an Impacted Ie-ft maxilla ry central incisor, due to an in verted u neru pted sup,'munwr,uy toot h. Th e decid uous too th is over-re tain ed. Accu ra te di ag nosi s o f the hd~ht of the im p.1(il'd tooth in thc, alveol us is not possible from this view. (b) Th e anterior ma xilla, see n o n oil lateral Cl.'p haluffielric radiogra ph. shows th e high im pil(tN centra l incisor, facing the labia l sulcus; Ic) a nd (d) representt f c SolID,' views a" (a) and (h) afte r remova l o f the SUf"?Tnumeral)' tooth an d bracket bonding to the exposed incisor. (Courl.~y o f Dr D Ha ra ry.I (e) A pa rallel in tr a-ora l photogra phic view. Th is film has been lM"rally inverted to simplify comparison.

RADIOGRAPH IC METHO DS RELATED TO THE D IAGNOSIS OF IMPACTED TEETH

Extra-ora! radiographs The panoramic view, while not showing the same degree of detail as a periapical film, has the adv an tage of simply and quickly offering

mou th. Thu s, w hile it gives a good twod im ensiona l represen ta tion of the tooth, this view ha s lim ite d value when vis ua liz ation of a n unerup ted too th is req uired, in the three plan es of sp ace .

a good sca n of teeth and ja ws, from TM joint to TM join t. It is p robably true to sa y tha t or thodon tists a re tod ay in general agreement that this film gives the most qu alita tive in fe r-

PA RALLAX METHOD

mation. to act as a starting point from wh ich to proceed to other forms of radiography, in line wit h the de man d s o f the pa rt icular s ituation in a ny given case. True a nd ob lique la teral ex tra-ora l views (Figs 2.4a-e) a nd the va riousl y angu lated oblique occlusal films all pro vid e info rmation

that may be used to complemen t the periapical film, particularly when too th displacement is severe. However, the use of any oblique film for the accurate localization of a bu ried too th may frequently be misleadi ng, be it a single pe riap ical, an occlusal or a lat eral jaw film . Th is being so, two incipient dangers exist . First, as we shall see in later chapters, a s urgical procedure may be mis directed a nd a flap opened on the w ro ng s ide of the alveolar p rocess. Second ly, mi sin terp retat ion of the too th' s position may lead the operator to assume a very fa vou ra ble prognosis for biomec ha nica l resolution when, in fact, the tooth may be in a co m pletely intractab le posi tion. Thus the choice of trea tm ent w ill be inap propri ate.

By following the p rincip les in volved in binoc ula r vis ion, two pe riapical views of the sa me ob ject and ta ken from slightly d iffe rent angles can provid e de pth to the flat, two-dimensional pictu re depicted by each of the films individu ally (Fig. 2.5). Thi s is of considerable help w ith distinguishing the bu ccal or lingual d isplacement of the can ine, which is low d ow n and fairly close to the line of the arch. Th e p rocedure is pe rformed in the foll owing manner (Fig. 2.6). 1

A periapically sized film is placed in the mouth, w ith the pa tient' s finger holding it against the pa latal as pect of the area w he re the too th wou ld no rm ally be situa ted. The x -ray tu be is d irected at righta ng les to a ta nge nt to the line of the arch a t thi s poi nt, as for a ny peria pical view

THREE-DIMENSIONAL DIAGNOSIS OF TOOTH POSITION As dentists, we arc ve ry used to seeing periap ical films of ind ivid ua l teet h, and, p rov ided that the teeth conce rned a re in the line of the arch, the se films ha ve ma ny advantages. Howeve r, in th is view, the x -ray tube is no t directed in th e true horizontal, true ver tical or true late ral pla nes. As ide fro m radiogra phy of the mand ibu la r poste rior tee th, the tube is always tipped a t a n angle to one or more of these pla nes . Th is is un im porta nt for a n eru pted too th, s ince the th ird di mens ion is supplied by the di rec t vision w ithin the

Figure 2.S The left periapical view. oriented for the central incisor s, shows the crow n of the camne superimposed on the d istal half of the central incisor mot. Th~' rmddlc film, rotated 30" to the left, shows the canin e overlapping only the lat eral tnctsor roo t. By ml aling the cen tral bea m ,1 fur ther 30", superimposition of Itll' canine over the lateral incisor root h as been eliminated. The canine is pillol tally displaced.

17

18

- - - - - --

-

2 23 21

23 21

Fig ure 2.6 A d iagra mma tic representa non o f the parallax method . If the \ll.~·n·d~ '-'y t' p''t.'n; alo ng the axis of the X-ray beam in each Col"". the image on lilt> film w ill be easy to I\'CUJ15truct.

and at the appropriate angle to the horizonta l plane. 2

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - ----'-'-----'---------'------

A second film is pla ced in the mouth in the identical posit ion, bu t on th is occasion the X-ray tube is sh ifted (rotated) mesially or d ista lly round the arch, but held at the same angle to the horizontal p lane plane and di rected at the mesially or dis tally adj acent tooth. To ach ieve this, the tu be should describe between 30° and 45° of an Me of a circle wh ose cen tre is somewhere in the midd le of the p alate.

Let us assume tha t a righ t unerupted canine is pa latall y pla ced (Fig. 2.6), then this tooth will be close to the m iddle of the pictur e obt ained in both films. However, in the first pi ctu re, where the tube was d irected over the designated canine area of the rid ge, the lateral incisor root will be on the right. If the cani ne is also we ll fo rwar d, the re w ill be so me overlap of the can ine crown an d the lateral incisor root. On the seco nd picture, taken from the

fron t, the right lateral incisor root and the cro wn of the pa latal canine will be in the mid d le, superimposed on on e ano ther to a much greater deg ree. Jacobs (1986, 1987) enjo ins the obse rver to use the right eye in p lace of the x -ra y tube and suggests the useful exercise o f hol d ing up two fingers vertically at eye level, with one obscu ring the o ther. If the observer now closes th is eye and ope ns the other, h is or her new vantage poi nt fo r inspection will have resu lted in a visu al separation of the two fingers. Th rough the left eye, the obscured finger will ha ve ' mov ed' to the left of the forw ard finger, to become partially visib le. Transferri ng this to the rad iographic context, in the second pictu re, the too th furthest from the tube [l.e. the pala tal toot h ) will ' move' in the same d irection that the X-ray tube has tr avelled from the first exposure. This method is very useful in cases where there is a m inim al he ight d iscrepancy between the erupted and uneru pted ad jacent teeth (Fig . 2.5). However, when the canine is high and the periap ical view shows no su pe rim posit ion of the canine with the roots o f the erupted teeth, o r where the superimposition is only in the apical area, then the overall pictu re may be very m islead ing and a different met hod of locali za tion should be used. The periapical view is d irec ted from above the occlusal p lane an d in an ob lique downw ard and med ial d irection , wh ich di stances the palatal canine from the roots of the othe r tee th and makes it ap pear higher than the anatomy of the maxilla wou ld allow. Tn the incisor reg ion, an unerupted perm ane n t incisor may be associated with on e or two supernumerary teet h (meslodcns) . The parallax met hod is insu fficiently clear in the se cases, because of the pr esen ce of two or three hard tissue entities in the bo ne, superimpo sed on the outline of the root s of the d ecid uous tee th and at va ry ing heig hts in the alveolus.

Radiog rap hic views at right-angles Rad iogra phic views may be taken at righ tangles (Seward , 1968; Hunter, 198] ) to one

RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH

(.)

(b)

«)

Figure 2.7

(a) The trw lateral cephalometric radiogr aph shows both canines superimposed, ill a higher levelthan th., other Il'CIh. Their axial inclination in the aotero-posterior plane is favo urable, with the crowns and "'pin'S apparontty normally located . (b) The pos tero-anterior cephalom e tric radiogra ph shows the fwo camncs !'imilarl)' anguletcd, wifh their apices in the line of thl' arch and thl' crowns dose.' to the mid line. From IhL~ Iwo films, we molY concl ude tha t the apices art.' ideally ploln-d an d that the long ""lOS of the It...·!h hav e a downward, mesi al a nd palatal incli nil(ion. (0;:) The pa no ram ic \ -il' W of the same pa ti.'nl. Th., apF"'a rancc of ca nines c!0S<' 10 the m idline is very simil.u ttl that .......n on th.· pos teroanterior ccphalomcutc radi og raph .

anothe r in various ways, bu t, for the met hod to be of value, it mu st be possible to determine the exact o rien tation in space of both the film and the central ray, by obse rving other struc tu res on the film. Thi s requirement is very difficult to satisfy when a v iew is soug h t at right angl es to the periapical v iew . Standardization, w hat is requ ired is the stand ard ization of views wit hin the confines of a strict ad herence to the planes of space. A true lateral view (Fig. 2.7a) will give exact information regard ing both the antero-pos terior and vertical location of an object, relative to other struct ures tha t may be seen both on that ra diograph and clinically. It will no t g ive any clue to the bucco-hngue l (tran svers e-pl ane) pictu re. A true occlusa l view will p rovide positional information in bo th the an ter oposterior an d tran sverse p lane s, but not the vertical plane. The th ird possibility is the true postero-anteri or view (Figs 2.7b,c), wh ich defines the he ight (vertical plane) and the

bucco-Hnguel relatio nsh ip only. By combining th e resu lts o f any two of these th ree films, three-d imensiona l localization may be accurately determ ined . Translating these p rincip les into rad iographi c practice p resen ts some difficulties. However, th ese arc not insur moun tab le and, insofar as they present the clinician with accu rate positional visualizat ion of the unerupted tooth, they arc ent irely worthwhil e. In the rnandi bulnr po sterior area, we have pointed ou t that the routine per iapi cal radio graph is also a true lateral view, with the X-ray tube po in ting at righ t-angles across the bod y of the mandible, in the hori zontal plane. The height and mesio-di stal position of a bu ried tooth may then be accu rate ly defined . The occlusal rad iograp h of this area is d irected at righ t angles to the occlusal p lane, and adds the bu cco-Hngual d imension to com plete the three-d imensional p icture.

19

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

~=~===~== ===_'_

2O

(. )

(b )

Hgure 2.8 The tru e la teral an d true occlusal view s, ta ken tog eth er, pro vide all the info rmation needed for an accu ra te positional assessment of crown and root in the three planes of space. (ill The peria pical view (a tru e lateral in this case ) of an impacted mandibular right second premolar shows the tooth to be tipped distally 60" from the vertical. with its incomplete apex at the correct height and mesio-dis talloca ticn. (b ) The true occlusal view sho ws the crown oi the tooth to be lingua l 10 the molar, and the apex 10 be in the bucco-lingeallme of the arch. The long axis of thc tooth, proceeding from its ide ally s ited i1f'l'J(, may be d escribed as rising at a 30" an gle in a dis tal and lingua l direction, 10 oVl'rlap th e mo la r

roots on the lingual side .

Accord ing ly. these two views will p rovide accu ra te localiza tion of the po sition of un erupted tee th in th is area (Fig. 2.8). Fo r most orthodontic cases, the lateral cephalometric rad iogra ph is an essen tial prerequi site and, aside from the rou tine mea su rement of angles and planes, this film sho uld also be used to gather valuable informa tion regar di ng the location of unerupted teeth. The lateral cephalogram represents a true lateral view of the skull, and, for the pre sent purposes, of the ante rior max illa in pa rticular (Fig. 2.7a). Altho ugh ther e arc many supe rimposed structures on this area, the outline of a canine may be clearl y see n. The d irection of the long axis of the tooth in the an tero-posterio r and ver tical planes may be defined, toget her with the mesiodistal positions of both crow n and apex. If a cepha lometr ic radiogra ph is not ava ilable, the same view of the an terior maxilla may be obta ined on an occlusally sized film. This film is he ld vertically against the cheek

and parallel to the sagitt al p lane of the skull. The X-ray tube is d irected horizontally above and parallel to the occlusal plane from the op pos ite side of the face, an d at righ t-angles to the film . The result is called the tangenti al view and h as the ad van tage of simplicity. This view is particularly usefu l in monitor ing progress in the resolution of impacted incisors du ring active tre atment. At the age at wh ich m ost pa tients first p resent wit h an im pacted centra l incisor (around 8- 10 years), the perm anent canine teeth ar e unerupted and are located both well forward and high in the anterior max illa. Thus, on the lateral ceph alometric or tangenti al view, right and left canines will be impossible to d ifferen tiate ind ividually. The root s of the incisor s, at the same heigh t as the canines, as well as the su perim posed images of the more inferiorly p laced crow ns of the erupted in cisors and decid u ous canines, will all be indi stinguishable fro m one anot her and from sup ern umerary teeth that may also be p resen t. For this

RADIOGRAPHIC METHODSRELATED TO THE DIAGNOSIS OF IMPACTED TEETH

Figure 2.9

A dilacerated cent ral incisor so-en in the la teral o.'phalomctri c rad iograph.

reason, the lateral view may be of limited value in cases where there is obst ructive impaction. w ith mi nimal d isp lacement. Whe n gross d isp lacem ent is p resen t, however, the outline of the altered axial inclination andheigh t of the tooth can usually be delineated, despite the conside rab le superimposi tion of other tee th. Nowhere is this view a greater asset than when a dil acerated too th is presen t, since it separates ou t this malformed too th, superi orly, from the roo t apices of the other teeth and from the permanent canines, becau se of its relative height (Fig. 2.9). Fu rthermore, its morphology may be seen to bes t ad vantage from this aspect, wh ich allow s definitive and accu rate di agn osis of the cond ition to be made, together with its precise relations vis-avis su rround ing structu res. The tang en tial view sho uld be con sidered an essen tial requirement in radi og raphically record ing the dtlaccra tcd centra l incisor. For max illary can ines, the lateral v iew is extremel y usefu l. It sh ould be remembered that most im pacted maxillary canines are d iagnosed in the full pe rmanent dent ition, when all the othe r tee th wi ll have erup ted. This dema rcates the canine at a h igher level than the o ther tee th. A post ero-anterior ceph alometric film is used less rout inely in ort hodontics, bu t it

offers the clinician the op por tunity to view th e maxilla in a d ifferen t p lane, the true postero-an terior view (Fig. 2.7b), w hich is at right-angles to the latera l cephalogram. The overlap of structures of the base of the skull and the max illa renders detail of ind ividual tee th less clear, bu t a good pos tero-anterior radi ogr aph will show the height o f bo th the crown and the root of a mark ed ly d isplaced too th, as w ith the lateral fil m. Th is view also shows whether the roo t apex o f an ectopic pos terior too th is in the line of the arc h and how far the crown is deflected in the pa latal d irect ion . The bucca-lingual tilt of the long axis of the too th will be p lainly visibl e (Fig. 2.10). However, the view is less p ractica l in the m andible, where the body is oblique to the cen tral ray. There is usually excessive overlap, mo re radio-opaque bone an d d ifficulty in discerning even ma rked ly buccalingu ally di splaced teeth. An occlusal p rojection o f the anterior maxilla (Fig. 2.3) offers the po ssibility to view in the third p lane o f space, at righ t-angles to each of the two earlier rad iographs, and to record the pos ition of the d isplaced incisor or canin e without overlap . However, for it to be of greates t value, it is important to p roject the X-ray beam th rou gh the lon g axis of the maxillary teeth, as jus t described. Any two of these th ree views (the later al cephalogram or tangential view, the posteroant erior ceph alogram and the true occlusal) will p rovi de complete information reg ard ing every aspect of the height, bucco- ling ua l and mesi o-dis tal location of the crown, the root, and the d egree of tilt of the long axis of the imp acted tooth and its relation with neighbour ing teet h. The postero-anter ior and occlusal views, how ever, arc 110t always as clear as is desirable, and they may need to be repeated or di scar ded . The lateral cephalometri c or tangential views in a cast' of bilatera l canine imp action may crea te conf usion, since one canine will be superimposed on the other and d istingu ishing them may be a p roblem, alth ough othe r views will usually facilitate di fferen tiation. Two id en tically orien ted and superimposed canines (Fig. 2.7) will obviously not need to be d ifferen tiated. Fr"om these aspects, it is very easy to bu ild

21

22

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

(.j

(b j

Fig ure 2.10 (e.b] Extracted portion of the later al and postero-ant erior cephal ome tric views, to show an impacted max illary left second premolar to be loca ted with its apex in the line of the a rch, but superiorl y di s plaCl.·..t Th{' cro w n is displaced pa la tally, close to the m id line

and the long axis is strongly palatal, slightly dow nward and slightly distal. (c) The periap ical film gives the misleading appearana' of the crown being dis placed superiorly and anteriorly. (Co urtesy of Dr I Gill is.) «j

up a three-d imensional pi cture o f the exact position and an gu lation of the im pacted tooth and to define the type of movement that will be necessary to b ring the tooth into align -

ment. When building this compos ite menta l reconstruction o f the position of the un erup ted too th in s pace, the desig n of the appliance needed to resolve the impaction is simplified and fewe r surprises are likely to be encountered . It is, however, an important p rerequisite in all these cases to examine a periapical view of the tooth, to eliminate the possibility of local pa thology, which could be missed on the extra-oral vie ws.

CT SCANN ING Recen tly, the usc of comp u ted tomogra p hy (CT) scann ing h as been su ggested (Ericso n and Ku rol. 1988a,b) for identifying the exa ct position of the palatally impacted canine, par ticula rly when root reso rp tion of the lateral incisor is suspected (Ericson and Ku rol. 1987). cr scann ing is a method in which clear serial radi ographs m ay be taken at grad ua ted depths in any part of the human body (Fig . 2.11a). At the same time , this technique allows the eli m ination of the su peri m position of othe r stru ctu res that we ha ve seen w ill

23

RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH

(.)

(bl

(d )

(el

(-)

Figu re 2.11 (a ) The lateral skull r,ld iogr,l ph sh ow s the direction and sepa ratio n of the indiv id ua l CT "slices', (b-e) These sections dt'p ict most clearly tht' midline slIpt' m u merar y loath a nd its rel,l tion ~hi p to the adja cent teeth in all thr ee pl ant'S o f space. (Co u rtt'Sy of Dr 0 Eiscnbud.]

obscu re the image of the object tha t we are attempti ng to view in trad itional radiography. In recons tructive dentistry, this method has been developed to allow accura te placement of implants (Schwa rz et al, 1989). Although it ha s excellent pot ential for the d iagn osis o f the position of im pacted and supern ume ra ry teeth , the large do sage of rad iation is difficult to justify for all excep t the exceptional case. By viewing seria l rad iogr aphic 's lices' of the maxilla (Figs 2.11b-c), the relationship of the im pacted too th to adjacent teet h, in all three p lanes o f space, may be accur ately assessed , as can the positions o f CTOwn and apex and the inclination of the long axis of the

tooth. In th e following chapters, we sha ll describe how the relative difficulty of br inging these teeth into their proper position is depe ndent on advance knowled ge of the exact positions of bot h crown and root apex. We sha ll conclude th at variations in root apex displaceme n t, in particular, prejudice both the ability of the orthodontist to co mplete the exer cise and the periodontal p rognosis of the tooth, when the treatment is finally co mpleted . The metho d may also give accu rate information regardi ng ear ly root resorp tion, pa rticula rly of the bu ccal and palatal su r faces of the roo l. Th is may not be possible to d iagn ose by any o ther me thod , prior to treatmen t. It therefore ma kes sense that for those

24

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

pat ients in whom the re is a suspected d isplacement of the long axis of a tooth, due to an abnormal orientation of the rool apex or the presence of root resorption (Ericson and Kurol, 1988b), the use of high-resolution com puted tomography should be considered.

ecto pically eru pting maxillary canines - a case report. Elir I Orthod 10: 115-20. Ericson S, Kurol J (1988b) Resorp tion of maxillary late ral incisors caused by ectopic eruption of canines. Am I Orthod Dentojac Orthop 94: 503-13.

Although CT scanning units are relatively few a nd ima ging is expensive, their us e is increasin g. a nd they a re now more freely availab le to the orthodontist in p ractice . It ma y still be d ifficu lt to just ify us ing the

Hunter S6 (1981) The radiographic assess ment of the une rupted maxillary canine. Br Dent 1 150: 151-5.

method on a routine bas is for the occasional and more straightforward case wit h one or two impacted teeth . However, its use in cases of multiple impactions, particu larly cleidocranial dysplasia, has mu ch to offer in the accurat e pla cing of the very la rge numbe r of impacted teeth, both at the treatment planning stage and the subsequen t surgica l phases.

Jacobs SG (1987) Exercises in the localisation of unerupted teeth . Austr Orthod J 10: 33-5, 58- 60.

Jacobs SG (1986) Localisation of the unerupted maxillary can ine. AI/sf r Orthod 1 9: 313-16.

RA (1982) A Guide to Dental Radiography, 2nd edn. Wright PSG, Bristol.

Mason

Ong A (1994) An altern ative techn ique to the vertex / true occlusal view. Am J Orthod Dentcfac Orthop 106: 621-6.

REFERENCES Ericson S, Kurol J (1987) Rad iog raphic examina tion of ectopically erupting maxillary canines. Am I Orthod Dentojac Orthop 91: 483-92. . Ericson 5, Kurol J (1988a) CT d iagnos is of

Schwarz MS, Rothman SLG, Cha fetz N, Rhod es M (1989) Computed tomography in dental implantation surgery. Dent Clin N Am 33, 555-97. Seward GR (1968) Radiology in general dental pra ctice. IX - Unerupted maxillary canines, central incisors and su pe rnumeraries. Br Dellt / 115: 85--91.

3 SURGICAL EXPOSURE OF IMPACTED TEETH In collab oration with Professor Arye Shteyer and Professo r Joshua Lustmann CONTENTS • Aims of surgery for impacted teeth • Surgicallntervenlion without orthodontic treatment • The surgical elimination 01 pathology • Buccal lyaccessibl e Impacted teeth • Part ial and fu ll flap closure on the palatal side • A con servativ e attitude to th e dental follic le • Cooperation between su rgeon and orthodontist • The team approach to attachment bonding

AIMS OF SURGERY FOR IMPACTED TEETH For imp acted thi rd molars, treatment alternatives and opportunities for cho ice are few, and. in the majority o f cases, extract ion is ad vised . However, for othe r impacted tee th, this is not so, and seve ra l lines of treatment may p resen t (McDonald and Yap, 1986). Neverth eless, in the pa st, the deci sion as to how a particular im pacted tooth shou ld be treated was most often decided by the or al surgeon, who also, by and large, deci de d upon and stage -managed the alternatives. This situation has cha nged in recen t year s. Prior to the 1950s, most orthodo n tists were unprepared to ad apt their skills and ingenuity to the task o f resolving the imp action of maxillary canines and incisor s. Accord ingly, the or thodo n tists them selves referred patients to the oral su rgeon , who would decide if the impacted too th could be brought into the dental ar ch. Where the circum stances were potentially favourable, the tooth wo uld be surgically exposed, and, when the su rgical field was d isplayed fu lly, the su rgeon would make his assess ment of the p rognosis of the

case, decide and act solely in acco rd ance with hi s own jud gemen t. In this way, man y po-tentially re trie vable im pacted tee th were extracted. There a re no surgical methods, other than transplantation . by which positive and active align ment of an impacted tooth may be carried out. The best a su rgeon may do is to provide the optimal env iron ment for nor mal and un h indered eru ption and then ho pe and pray that the tooth will oblige. With th is in mind, therefore, tho se teeth that were considered wor th trying to recover we re wide ly exposed and packed with gauze soa ked in Whitehe ad 's varnish, to protect th e wound during the healing ph ase and to prevent reheating of the tissues over the tooth. For a varie ty of reasons, several oth er ste ps were taken, dependin g upon the preferences and beliefs of the operator, with the aim of provid ing 't hat extra something ' that wo uld impro ve the chances of spontaneous eru p tion still fur ther. These measu res were o ften very emp irical in n ature, and in clud ed one or mo re of the following : (a ) clearing the follicula r sac comp letely, inclu ding in the eEJarea;

26

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(b) clca n ng the bmw a ro und the too th, dow n to the eEJ area, to dissect out a nd free the entire crown an d the corona l porti on of the roo t of the Impacted too th; (c) 'looseni ng up' the too th, by subluxa ting it wi th an eleva to r; (d) bone-channelli ng in the desired direc ti on of movement of the too th; (e) pocking g,l uZC or hot gutta pe rcha in to the a rea of the CEl , und e r p ressure, in order to apply force to deflect the croption pa th of the tooth in a particula r d irecno n. In those years. few patients were referred to the o rthodontist until full eruption had been achieved and the tooth then needed to be moved horizontally into line w ith its ne ighbOUTS. Up to that point. the problem was considcrcd to be w ithin the realm of the oral surgeon. In many cases. 's uccess' in achieving the eruption o f the too th was pyrrhic and often subordina ted to failu re of .1 d ifferent kind . namely the period o ntal condition of the newly eru p ted tooth a nd its poorer su rvi val po ten tia l - its prognosis. Th is w as the inevitable res u lt o f the aggressive a nd over enthusiastic su rgical techniques tha t had bee n us ed. w hic h ty p ically left the too th w ith an elongat ed clinical crown, ,1 lack of attached gingiva an d .1 red uced alveol ar cr es t heigh t (Odenrick MId Modcc r. 1978; Boyd , 1982, 19M; Becker ct al. 1983; Kohavi ct .11, 1984a, b).

~

(.1

(hI

SURGICAL INTERVENTION WITHOUT ORTHODONTIC TREATMENT W e COIllC a c ros s Cil SCS in which th e on ly clini cal pro blem rel at es to th e im pacted tooth, the occlusion an d nllgnmcnt being otherwise acceptable. For these pa tien ts. the follow in g question needs to be addressed : What surgi cal methods MC a vailable tha t may be expected to pro vid e a more or less com plete solu tion , wi thou t out s id e assistan ce? To be in a position to a nswer this question, it is necess ary to provid e a d escription of the position of the teeth tha t wi ll respond to this kin d of treatment .

lei Figuree 3.1 (,1) A lo·yt'.u-ul,l k nl,llt' exhibitsa n Ullt' Tu ple,.I maxillary ldt canine, w hich h,IS been pn'St'nl in thi" povirion fur 2 yt'.lTh MId h,IS not progres sed. (b) The loo th W,lS ,'xpf)';cd, an d Ih,· flap , whi ch co ns ist,,,,l of thic kened mU(O"'l. was apically repo sitioned . (c ) At 9 mon ths post-surgery. the t"" th h,l" erupted nn rm"ll y. (Co ur t,'!'>y of L Shapira.)

27

SURG ICAL EXPOSURE OF IMPACTED TEETH

Figu re 3.3 Following exposure and packing, tlw tooth has erupted spon tan<-'(lusly. bu t thO;' bon... l...vel is compromiso."d.

(b)

generally lead to a fairly rapid eruption of the soft tissue impacted. too th, particularly in the maxillary incisor area. The mo re the tooth bulges the soft tissue, the less likely is a rebu rial of the tooth in healing soft tissue and the faster is the e ru ption .

Figu re 3.2 (a) Soft tissue impaction o f max illa ry cen tra l incisors. (b) Apical reposi tioni ng (If bo th buccal and pa latal flap s to leave the incisal edges e xposed . (Cou rtesy o f Professo r J Lustma nn.)

Expos ure only A superficially pla ced too th, palpable beneath the bulging gu m, is an obviou s candid ate. This type of tooth may be seen in the maxillary canine a rea (Fig. 3.1), but also in the mand ibu lar premolar area (sec Fig. 1.8) and the maxillary centra l incisor area (Fig. 3.2), usually where very early extraction of the deciduous predecessor was performed wh ile the immature permanen t tooth bu d was still deep in the bone and u nready for eru ption. Healing occurred , and the permanen t teet h are unable to pe netrate the thickened mu cosa (Dibiase, 1971; And reasen and And reasen, 1 99~ ) . Removing the fibrous mu cosal cove ring or incising and resutu ring it to leave the incisal edges exposed (Figs 3.1a and 3.2b) w ill

Exp osure with pack Taking this one step fur ther, we can SI,.'C that a less super ficial toot h req u ires a more rad ical exposure p roced ure, and may need a pac k to p reven t the tissues frum rehe eling over the too th. While the surgeon may be rewa rded with spon taneous eru ption, th is will take longer, and a comprom ised per iodo ntal result should be expected (Fig. 3.3). We have d efined over- retained de cid uous teeth as teeth still present in the mou th when the ir permanent su ccessors have reach ed a stage o f devel opment that is compa tible with their full eru ption. These decid uou s teeth ma y then be considered as obs tructing the normal developm ent tha t wo uld be expected to procee d in their absence, The deciduo us tee th should be extracted, bu t p rov ision sho uld be mad e to encou rage the pe rmanent teet h to erupt quickly. Many of these permanen t teeth wit h dela yed er u ption arc obnormally low in the alveolus, and Me in d anger

28

THE O RTHODONTIC TREATMENT OF IMPACTED TEETH

~~----------'------------'----

of being rebu ried by the healing tissu e of the evacuated socket of the deciduous tooth. According ly, the crowns of the teeth sho uld be exposed to their widest d iameter an d a surgical o r pe riodon tal pack placed over them and su tured in p lace for 2- 3 weeks. Th is will encou rage epi thelializ ation d own the sid es of the soc ke t and , generally, pre ven t the re-fermation of bon e o ver the unerupted toot h.

Exposure with pressure pack Mild mesial impaction of a mand ibu la r second permanent molar be neat h the distal bulbosity of the first permanent mo lar is a condition that often responds to surgical interven tion and packing on ly. Th is in volves exposure of the occlusal su rface of the too th and the deliberate wedging o f some form of pack in the are a between the two teeth an d lea vin g it there for two o r thr ee wee ks. Duri ng this time, the pr essure w ill often succeed in eliciting a di sta l mov ement of the impacted molar, which may then erupt more freely whe n the pack is removed . The degree of con trol available to the operator in judging the amo unt of p ress ure applied and the extent to which the p ack interferes periodontally is minimal, an d lasting da mage to the periodontium is likely. Success in bringing about an improved position of the too th may thus not be matched by the health of its suppo rting s tructures in the final analysis.

THE SURGICAL ELIMIN ATION OF PATHOLOGY

Soft tissue lesions In Ch ap ter 7. we sha ll refer more sp ecifically to be nig n tu mo urs. Surgical treatment is the onlv trea tment tha t is indi cated for these conditi'ons in the first instance. This should be performed without delay, if only for reasons of obtaining biopsy material to confirm the innocence of a ten tat ive diagnosis. Orthodontic treatm en t should be suggested then bu t begun only afte r a filling-in o f bone h as B l e LJOTH~aUE' DE L'U N I 'lE R S rT ~ C ": P/I.RI S V

U.r::: .R. D" '; ' : l i '--' I:" /~! ': 1,ruO :: ;:' I , ' ~r-" '{ Q? 1 ? n

~Jl ("'I\II U

, ,,. , <::

brought abou t an improvemen t of the posi tions of the grossly displaced teeth, together with an imp rovement of the bony defect that w ill be ev ident in the anatomy of the alveolar bon e in th e area, which ma y take ma ny months to occu r. Duri ng th is time, the psycho log ical prep aration of the patient for the proposed or thodont ic treatment may be und er taken, which mu st begin with seeing po sitive results from a preventi ve dental health programme aimed at elim inating ma rgina l gingival inflammation an d redu cing the caries incidence for that patient. .

Hard tissue obstruction Obs tructive impaction invi tes the logical step of rem oving the offe nd ing body causing the no n-e ruption. On many occasions, this is pe rformed by the su rgeo n, wit hou t recourse to orthod ontic assi st an ce, and enjoys a va rying degree of succes s. ln Chap ter 5, we sh,111 refer to the re liability of spontaneou s erupti on, follow ing the va rious surgical pr ocedures inv olved in the treatmen t of impacted inciso rs. For the presen t d iscu ssion, we must recogni ze th at there is a significa nt numbe r of cases in which e ruption does not occur in a reasonabl e time frame . Undoubtedly, the position of most unerupted teeth imp roves with the passage of time, following the removal of the obst ruction, be it a supern umerary tooth, an odontome, res id ual decid uous roo ts or an infraoccluded p rimary tooth. However, many o f these teeth do not erupt without assistance, because of local dis turban ces caused by the recen tly removed obstru ction and the healing tissues. A hard tiss ue body occu pie s mu ch spa ce, and ma y cau se a gross d isplaceme nt of the developing too th bu d of the n orm al too th, both in term s of overall di st an ce from its p lace and in that the o rien tation of its long axis is also deflected. Thus the root or the crown of the too th may be deflected mesially, distally, ling ua lly or buccally , comprom ising its cha nces of spontaneo us eruption. Abnormally sha ped root s may develop in the

SURGICAL EXPOSURE OF IMPACTED TEETH

cram ped circumstances in wh ich they find themsel ves, betw een the disp lacin g influence of the pathological entity an d the ad jacen t teeth, on th e one ha nd , and the floor of the nose or lower bo rde r of the mandible (Becker and Shochat, 1982), on the other. Non-eruption disturbs the eruption pattern of the ad jacent teeth, which then assume abnormal relationships to one another, usu ally characterized by space reduction and tipping. This then provides a secondary physical imped iment to the eruption of the impacted tooth.

As we sha ll discuss in Cha pter 7, infraoccluded permanent teeth are usu ally ankylased to the surrounding bone, and, as such, cannot res po nd to ort hodontic traction. In many cases, the ankylosed area of root is minute, and may be easily bro ken by a d eliberate bu t gentle luxation of th e tooth. This is usually performed with an eleva tor or extr action for ceps, and is d one in su ch a way as to slightly (very slightly ) loose n the rigid con-

nection of the bo ny un ion, which is unbending. The tooth is not remo ved fro m its socket, nor is the aim eve n to tear the pe riod ontal fibres. The p urpose is to retu rn the tooth to the same degree of mobility that is cha racteristic of a normal tooth. Unfo rtunately, the fate of the too th that has und ergone thi s p rocedure is usually a rehealing and rea ttachment of the anky lot ic conn ection, leadi ng to a return to the origi nal situa tion. Acco rdin gly, th is approach can only be successfu l if a cont inuously active traction force is applied to the tooth fro m the time of its luxation. Th is force m ay then ac t to m odify the rche aling of bone , du e to the d istractio n os teogenesis (Ilizarov et al, 1980; Altu na et al, 1995) that it causes. If the range of force is small and loses its potency betw een visits for ad justment, reankylosis will result. Thu s, to be effective, it must be of sufficient magnitu de to cause di stracti on and of sufficient range to remain active between one visit fo r ad justment and the next. The risk is that a poor biomechanical au xiliary , insufficient force levels or missed appo intm ents may cause the exercise to fou nder, owing to reestabli shm ent of the an kylosis b ridge.

(. )

(b )

tntrsocclusion

Fig ure 3.-1 (al A high buccal canine exposed by circular incision of the sulcus m ucosa . (b) Follow ing alignm en t. the oral m ucosa is allached directly to the gingi va. (Courtesy of Dr G Engel.)

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ...:...:=...:...::.:..:....:...: _

30

BUCCALLY ACCESSI BLE IMPACTED TEETH There are fou r met hods ava ilable to resolve an u nerupted toot h th at is on the bu ccal side o f the ridge and high in the sulcus. Thcse are as follow s.

1

A circular incision

This may be made in the sulcus mucosa, im mediat ely over the crown, to expose the bony crypt immed iately beneath . In order to do this, the enti re su rgical procedure w ould inevitably be sited above the attached gingiva (Fig . 3.4). From the su rgical point of view, suitable access will have been provided to allow the bonding of an attachment. From the orthodontist's standpoint. the applicatio n of light extrusive forces of good ra nge p resents no particular d ifficult ies, an d red uction of th e imp action may be very rapid. Whilst this may satisfy both su rgica l and orthodontic demands, the periodon tic result will be poor, and there will be an elongated clinical crown . The ba nd o f attached gingiva will be tu rned palatal to the aligning too th, which cou ld create a factor for buccal positional rela pse at the end of trea tmen t. On the labial sid e, the too th w ill be inves ted with the thi n o ral mucosa, which offers a poor longterm p rospect und er cond itions of normal func tion for the fully corrected canine. In many of these cases , eru ption may occur naturally, with the tooth emerging through the su lcus mucosa and ab ove the attached gin giva . Prompt treatmen t will be needed if these teeth Me to acquire a normal pe riodon tal environme n t, wh ich will d ictate p reempting their eruption . The circular incision method provides no solu tion to th is.

2

Apica//y repositioned surgical ffap

This method, ., recog n ized and accep ted p rocedure in pe riodontics, was first d escribed in the contex t of surgical and orthodontic treat -

men t of uneru pted teeth by Vana rsd all and Co rn (1977). In their method and in the ab sen ce of the d eciduous can ine, a mucoging ival flap is raised fro m the cres t o f the ridge that includes attached gingiva (Fig. 3.1). If a decid uou s canine is p resen t, the flap is designed to include the entire a rea of buc cal gingiva that inves ts it, and the deciduous tooth itself is extracted . In eithe r case, the flap is detached from the underly ing hard tiss ue some wa y up into the su lcus , to ex pose the canine. The flap is then su tu red to the labial side of the cro wn of the permanent canine, to cover the denuded pe riosteum and overlying the cervical portion of the crown, while the remainder of the crown remains exposed . Subsequent eruption of the too th is accompanied by the healing gingival tissue, and, when the too th takes up its final positi on in the arch, it will be found to be invested with a good width of attached gingiva. When left unt reated, palpable unerupted tee th ma y take ma ny months to break throu gh the mu cosa and rea ch their fina l positions. Whe n an apically repositioned flap is pe rform ed , eruption is s peeded u p . Ad d itionally, with the sutu red so ft tiss ue applying some pressure on the buccal side of the tooth and assuming there to be space in the immediate vicinity, a bu ccal d isplacemen t may be spo ntaneo us ly red uced. If the unerupted too th is very h igh , the surgical flap, wh ich stretches from belo w the attached gingiva on the cres t of the ridge or at the free gingiva of the d eciduou s tooth up to the depth of the sulcu s, would be excessively large. Under these circums tance. the procedure is no t recom mend ed , since the ap ically repositioned flap wou ld then leave a wide area of the labial bony plate unnecessarily exposed to the oral en vironment. In a more recent stu dy, Vermette et al (1995) found several drawbacks in relation to the aesthetic and pe riod on tal results of the apically repos itioned flap techniqu e for buccal canines, wh ich had no t been previously reported. Tn uni laterally affected and trea ted cases, the clinical cro wn len gth was greater than the u nt reated control sid e and an uneven and unaest hetic ging ival ma rgin was often produced (Fig. 3.5). There was also a

31

SURGICAL EXPOSURE OF IMPACTED TEETH

occurred, without the use o f appliances (Fig. 3.1). In others, an attach ment may be bonded by the ort hodon tist at any app rop riate later da te and active extrusion sub sequently u nd ertaken .

3

Fig uno 3.5

Uneven a nd un aesthetic g ingival margin, band s of gingiva l sca rring and a lo ng d in i(al (TOWn, followin g api (al repositionin g of the flap cov e ring thi s form e rly buccally impacted ( an ine.

degree of atta chment loss and bone loss on the labia l surface, whi ch was con sidered as possibly related to an increased. poten tial for plaque accu mu lation that the proced ure seem s to encourage. Vermette et al (1995) also reported a vertical or thodon tic relapse in 61% of the tee th that had been erupted using o rthodon tic appliances, after trea tm ent had been completed . They specu lated that the reason for this is that, follow ing the api cal repositioning, the gingiv al tissue heals to the adjacent mucosa, pro d ucing soft tissue bands of gingiv al scarring. As the toot h is pu lled Inosally, th is mUCOS
Full flap closure

Th is was proposed by McBride (1979), and is a procedure tha t may be used rega rdless of the heigh t of the canine. A bu ccal su rgical flap is raised as high as is necessary to expose the unerupted canine. An atta ch ment is then bo nd ed to the tooth. and the flap is fully su tu red back to its former place. A twisted stainless steel liga ture wire th at has been threa ded throu gh the attach ment is then drawn inferiorly and throu gh the sut u red edges of the replaced flap, at the cres t of the ridge, or th rou gh the socket vacated by th e extra cted deciduous canine. Spontaneous eruption is less likely to occur than wh en the tooth remains expo sed, following apical reposition ing, and act ive or thodontic force w ill probably need to be applied to the tooth to bring abou t its er u ption. In this method , the too th erupts toward and through the attached ging iva area, which then becomes attached to the tooth and the su rrou nd ing alveolar process. This d osed-erup tion method compares favourably (Verme tte et al, 1995) with the apically repositioned flap method described above. The full flap closure method (closed eruption tech nique) shows no ten dency for an apical and u neven gingival position, nor does it produce a long clinical crown . There is no loss of att achment on the buccal asp ects, nor is gingival scarring prod uced with this method, and the pe riodonta l attachmen t is completely norma l. A fur ther and pa rticularl y significant d ifference between the two methods of su rgical exposure of the bu ccal canine repor ted in this work was that in the fu ll closure method, the re was no vertical relapse o f the treated canine follow ing the com pletion of treatmen t. However, the closure of the flap at the end of the surgical stage dictates the necessity for the

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH .::.:.-=-=.::.:....:..:.::..::.::.:.-"-==--' -=-"-=.::.:..::.:..::..::.=..::= CC

32

4 The relief of crowding to reduce canine displacement

Figu re 3.6

Buttonholing.

p lacement of an attachment, while the toot h is visible and in the surgeon's operatory. It cannot be left until a subseq ue nt visit.

The method has unequivocal advantages over the apically repositio ned fl ap me thod , and these have been attributed to the close similarity of the conditions brought about by full flap closure to those associated with normal too th eruption (Crescini et at 1995). On the basis of their resul ts, Vermette and co-workers question the indications for the continued usc of the apica lly repositioned flap method . A significant problem wit h the closed eru ptio n techniq ue is so metimes caused by a poor cho ice of bonded orthod on tic attachmen t. Since the midbuccal position o f th is too th is easy to expose and to bond to, the orthodontis t may be temp ted to use a conven tional o rtho dontic bracket in this ins ta nce (WongLee and Wong, 1985). Becau se of the bu ccal pro mi nence of the too th, the lack of buccal bon e and the rela tive tigh tness of the replaced flap, damage may be ca used to thi s mu cogin gi val tissu e by the bu lk of wid e and highp rofile conven tio nal bracket s (sec Fig. 4.4), w hich may lead to a breakd ow n of the overlying tissue , to cause a dehiscen ce or even 'bu ttonholing' (Fig . 3.6). O nce again, therefore, the use of an eyelet offers s ignificant advantag es due to its more modest di mens ions an d lower pro file, at least u ntil th e tooth has erupted and been b rou ght in to close promixity to the labial arch wirc.

If the d ispl acemen t of the canine has been due to crowding then it follows that spontan eo us improvement of th e position of the canine may well occ u r if the crowd ing is eliminated. Time ma y no t be on the s ide o f the clinician opti ng for th is a pproach, s ince the too th may e rupt th rough the oral m ucosa if delay is incurred. Nevertheless, for the case in w h ich this a p proach is to be used, a fu ll case analysis is req uired, leading to a d iagnosis and treatment plan for the ov era ll m alocclusion . If the crowd ing is to be d is pe rsed by d istal move men t o f the molars, it w ill take it longer time before sp ace is avail able in the canine reg ion, wh ich is the most common area w here this type of problem occu rs. Consider able d elay mu st be expected while the treatment is proceed ing, before spontaneous improvement of the canine pos ition ma y be seen. O n the othe r hand, a p remolar extr action will provide immedia te relief of the crowdi ng and an excellent opportunity for a self-correction o f the buccal d isp lacement and, with it, the disappearance of th e poten tial pe riodontal hazard .

PARTIAL AND FULL FLAP CLOSURE ON THE PALATAL SIDE Occasionally. impacted teeth that a re located on the palatal side are palpable imm ed iately beneath th e pa la tal muc osa . The surgical removal of a circu lar section of the ove rlying mu cosa (sec Fig. 6.26) to leave the toot h exp osed is tempting and has obviou s advantages. Howeve r, the palata l mu cosal covering is ve ry th ick and will leave a broad cu t sur face, w hich w ill te nd to close o ver u nless its edges are more radically trim me d back and the dental follicle removed . Thus, for a deep ly placed tooth, the exposure will ad ditionally need to be ma int ained using a su rgical pack. This type o f surgical approach will therefore leave the tooth with a soft tissu e defici ency and a long clinical crown at the completion of the orthodontic alignme nt.

33

SURGICAL EXPOSURE OF IMPACTED TEETH

As we have described for the b uccal side, full flap closu re on the palatal sid e req uires attac hment place ment on the exposed too th, p rior to resutunng. This then allows the too th to be exposed with the minimum of tissue removal and consequen t su rg ical trauma. When this is done and given appropriate or thodontic mechanics, the final result w ill show that the bone su pport for the too th, as well as the hea lth an d appearan ce of the mu cogtngival tissu es, are at their best. The accu mu lated ev ide nce that has been presented in the va rious clinical compa riso ns of su rgical method s of exposure (Heaney and Athe rton, 1976; Wisth ct al, 1976; Odenrtck and Modeer. 1978; Boyd, 1982, 1984; Becker et al, 1983; Kohavi et al, 1984a,b; Crescini et al. 1995; Vermette ct al, 1995) pro vid e a scientific basis to recommend the full flap closu re approach over any other.

A CONSERVATIVE ATIITUD E TO TH E DENTAL FOLLI CLE The den tal sac or follicle develop s from a meso dermal co ndens ation of cells on the outer surface of the exte rnal enamel epitheliu m of the enamel organ of a formi ng tooth, into a fibrova scu lar caps u le. The follicle has an inner vascu lar p lexu s th rough which the ena mel organ is supplied with n utrients d uring growth, and an outer vascu lar plexus concerned wit h en larg ing the bony crypt in which the toot h germ lies. The follicle encompasses the en tire tooth ge rm, and, as the roo t portion of the toot h is formed , the adjacent par t of the follicle transfor ms to beco me the periodo n tal memb rane, connecting the cem en tum cove ring of the d eveloping roo t to the developing alveolar bone. The enamel cu ticle is made up of a ke ratinou s de posit from the ameloblast s and the reduced enamel epi thelium, and is con tinuous wit h Hcrtwtg's epi thelial root sheath . Th is separ ates the cro wn o f the tooth from the follicle, from which the roo t develops and cementum forms. Becau se of th is separa tion between follicle and enamel, cementu m is not formed on the crown of the too th.

Eruptive mov ements b ring the tooth follicle in to close contact with the o ral mu cosa, the ir ep ithelia fuse , an d the too th thus breaks throu gh an epithelium-lined open ing. As eruption p roceeds, the rem aind er of the follicle eve rts and becomes tu rn ed ' insi de out' , with the red uced ena mel ep ithelium forming th e gingiva l cu ff and the most s uperficial point of attachment. Whe n im pacted w isd o m teeth a re removed surgically, the dent al follicle is always carefu lly d issected out to p reven t the possible later occu rrence of cys ts that ma y arise from res idual folli cle epitheli u m. How ever, wh en a too th is exposed, only its su rround ing follicle has an im portan t function to fulfil. This d ifference in attitude to the follicle of a tooth committed for extrac tion, compared wi th that of a too th th at is to be exposed and subsequently erupted into the m ou th, is basic and important to understand. Fro m stu d ies o f the cau sati on of external crown resorption of lon g-standi ng bu ried tee th, it has been found that pa thologic al changes occu r in the follicle su rroun di ng its crown (see Fig. 6.11) - changes that have brough t the enamel su rface in to d irect con tact with the su rrou nd ing tiss ues (Blackwood, 1958). It is ea sy to d raw a pa ra llel bet wee n this cond ition an d the artificially produced en vironmen t of an impacted too th tha t has been su rgicall y exposed and has subsequently become rebu ried in the tissues. If, for whateve r reason, th e toot h docs not erupt spontaneous ly, the re will be long-term d irect contact between the tissu es and the en amel of the tooth . In clear ing the su rround ing tissues for the purp ose of crea ting all adequate opening, which w ill not eventua lly close down , the surgeon will, gen erally , d eliberately and com pletely remove the follicle s urround ing the tooth (Fig. 3.7). Should spontaneous eruption then occur, the or al ep ithelium will grow down the sides of the opening. It will then attach mor e apically on the tooth than no rmal, and a comp rom ised ging iva l attac hmen t will resu lt. The erupted too th will hav e a longe r clinical crown an d red uced alveol ar cres t heigh t. The ap plication of or thodontic tra ction on ly

34

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - - - - - - - - - - - - - - - = - - - - -- - -

I' )

'b'

Fig ure 3.7

(a) A Ie ft impaclt>d ma\ iIIar)' central incisor has been ",xp(l~d and th e entire follicular Sole removed, p rior to cemcntmg a band (case trea ted before the advent of direct brac ket bonding to e tched crl,'mcl). (b) Two }'l 'ars posttreatment shows pOO l' F>in~i\',l l conte nt an d positional deterioration.

requi res an ope nin g in the foll icle that is large enough for the a ttachment to be placed, while the rest of the follicle ma y be left inta ct. The su rgical flap m ay then be fully

sutur ed back and the wound comp letely closed. O rthodontic tract ion bri ngs the too th towards the oral cav ity, and the follicle fuses wi th the or al mu cosa, to mi m ic no rmal erup tio n. Th is lea d s to the est abli shment of a normal gingival a ttac h me nt (Crescini et al, 1995). A new loo k mu st be ta ken a t the s urgical p la n fo r the exposure of unerupted teeth. If bon d ing w ill not ta ke p lace at surgery th en a w ider expos u re m us t be pe rformed and a su rgical pac k may 0I..'Cd to be placed, in order to p re vent the reclost ng of the wound. It is

im portan t to av o id the over-zealous su rgical remova l of the foll icle and d amage to the cemcnto-e na mel junction a rea by forcefu l placement of the pa ck, a po ore r resu lt sh ou ld be expected . A ttac h me nt bond ing m ust subse que ntly be pe rfo rmed a t a convenient tim e aft e r pa ck re moval, at the orthod onti s t' s leisure. How eve r, at this time, the heal ing a nd swollen g ingival tiss ue su rrou nd ing the exposed too th w ill be tende r, will bleed wi th min im al p rovoca tion and w ill be cov ered with plaque, s ince effective toothbrus hing is u nlikely to ha ve been po ssible. A wide flap des ign has the advantage of display ing the a rea of bone covering the too th, w hich is helpful in identifying of the exact site of the too th . A canine too th buried in a bony crypt in the palate will alter the shape of the palate inferiorly by creating a distinct bu lge of thinned bone, and this w ill be all the more obvious if m uch of the surro un ding bone is also vis ible . Th is is just as tru e in the labial pla te of the maxilla an d in the bu ccal or lingual pla te o f the ma nd ible, w here the too th in question may be a ma xilla ry central incisor, a seco nd premo lar or an y other too th. A ge nerous fla p design helps to di stan ce the edges an d u nd e rside of the flap fro m the field of o perati on is im po rta nt if conla minat ion w ith blood is to be a vo id ed during bo nding. We ma y sum ma rize the ad vantages a nd d isad va ntages of complet e fla p closure w ith the alte rna tive techn ique in w hich exposure is ma in ta ined by red uci ng the s ize of the flap and pa ckin g the wound .

Prill/aryfull fla p clos ure Advantage s: • ra pid hea ling • less d iscomfort • go od post-ope ra tiv e haemostasis • less imp ed ime nt to fun ct ion • conserva tive bone removal • im med ia te tractio n possible • reli ability of bond ing. Disad va nta ges: • p resence of o rthodont ist requ ired • bon d fail u re d icta tes re-ex pos u re • di fficu lty in ga ining d ry field .

35

SURGICAL EXPOSURE OF IMPACTED TEETH

SecoJldary doeure toitli }lllck Ad vantag es: • o rthod ontist's presence unn~cessa ry • bon d failure - needs no surge ry. Disad va ntages: • more d iscom fort • w ider bone exposure • man)' visits to cha nge pa cks • grea te r risk of infect io n • bad tast e a nd smell in mouth • bond ing reliab ility poo rer • de laved initi ati on of trac tio n • poorer periodontal condi tion . Once the bo ny s ur face ha s been bared and the loca tio n of the buried too th id en tified, the thin ov erly ing bone may be lifted off ve ry ea sily. Th e su rgeon will generally use a sha rp chise l w ith light ha nd p ressu re to cut open the bony cryp t and to remove the su pe rficial pa rt of its wall. The bo ne is ofte n pa per thi n, and ca n e ven be cut w ith a sha rp scal pe l. Im media tely be ne ath the bo ne, the dental follicle will be seen to glis ten in the bea m of the opera ting la m p . A w indow sho ul d be cu t in the follicle to fu lly match the exten t of the ve ry min imal bo ny opening tha t ha s already been ach ieved, in order to see the ori en tati on of the tooth as it lies in its cry pt. As we shall describe in la ter chapters in this book, it is important to place the a ttachment as close as po ssib le to the midbuccal position of the crown of the tooth, in order tha t traction will ten d to improve any ex isting rotation, thereby reducing the amount of mecha no thera py to w hich the tooth w ill ne ed to be subjected . For this reason. where a rotated toot h is exposed, the bony opening should be exten ded around the crown of the too th, toward s the midbucca l ar ea of the crown, provided tha t this may be done wit h ease and w ith the inflict ion of relati vely little further surgical d a mage. In th is insta nce, flap rep lacement ma y be completed and the pigta il ligatur e, tied into the ne w ly placed attachment, drawn in the d irection of the p roposed ta rge t s ite in the d enta l arch . Du rin g expos ure of the crow n of a too th, instrumenta tion of the enamel surface is no t detri mental to the e ru ption process or to

the quality o f the treat ed result. Howeve r, exposure and instrumen ta tion o f the roo t su rface a re potentially da magi ng . Expo sing the roo t su rface p re-supposes that the ccmcn toena mel junction, the na tural a tta chment of the toot h, w ill ha ve been ruptured, a nd re ne wed a ttach me nt w ill probab ly onl y be es tablished more apically. Addi tion ally, pe riodonta l fib res a re severed. cementu m exposed . a nd subjected to drying (sucti on and air syring e) a nd con tact w ith fore ign s ubsta nces (etcha nt a nd bondin g ma terials). Th is ca n lead to the la ter initia tio n of a reso rptio n p rocess on the root surface, a nd to a nky losis a nd failure of eruption in ex treme ins tances. More com mo n sequ elae include serious ly reduced bone su pport, long clinical cro.....ns, poor gingival att achment and con tou r, chronic gingiva l margin inflammation and pocketing . In sho rt, the quality of the periodon tal res ult will be compromised.

COOPERATION BETWEEN SURGEON AN D ORTHODONTIST From th is d iscu ssion, the rea der shou ld have come to realize the na rrow lim ita tions of the surgeon's ability to ma te rially ass ist these cases and h ave come to appreciate tha t the inclu sion of orthod ontic p rocedu res offe rs most cases a bett e r cha nce of success. Today, orthodontists have come to play a more domina nt role in the initi al stages of the treatment of im p acted teeth, by providing the traction that is ne cessary to encourage this er u pt ion a nd, in ma ny cases, to do so successfully in teeth tha t wer e previously felt to have a poor prognos is for er u pti on. The stat us of an impacted tooth tod ay is la rgely d epend ent on the ab ility an d. the ingenui ty of the orthodon tist to apply light traction in an appropriat e d ire ction and with efficient means, once the tooth ha s been made accessib le by the ora l s u rgeon. If or thod ontic traction is available to the pat ient, there is little merit in the su rgeon offeri ng an y of the ot her p roced u res listed ab ove, since the re is no av ail able evid en ce to sugges t tha t these proced u res may e nha nce the oppo rtu nity for

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

orthodontic resolution wi thout causing concurrent ha nn. We may therefore conclude that, with respect to the treatment o f impacted teeth, the aims of the oral surgeon sho uld be limited to: (a) the pro vision of access to the buried tooth; (b) the clearing of an y obs truction in the tooth's eruptive path , such as supernumerary teeth, od ontomas or thickened over lying mucosa ; (c) taking an active part with the ort hodontist in bondi ng an attachment to the exposed teeth at surgery, by maintaining hacmostasls, which is so critica l in ensuring success. The single mo st important aim of the surgi cal ep isode is to prov id e the means by which force may be ap plied to the tooth in question, thro ugh sever al subseque nt visits, over a longish time span and in as simple a mann er as po ssible. For this to hap pen. an atta chmen t has to be securely bonded and a firm ligatu re d rawn to the exterior, to which steel or elastic ligatu res or an aux iliary spring may be tied . A sharing of the responsibility for the resolution of the impaction sho uld be un dert aken by oral surgeon and orthodontist, with one specialist complementing the othe r in applying their very special skills to the resolution of the immediate task. Together, they possess all the tools that are needed to complete the job. Thei r combined efforts sho uld be geared to achieving th is. Bond ing an attachme nt to the too th at a late r visit, a few weeks after surgery has been performed, has the adva ntage of not requlring the p resence of the ort ho do ntist at the surgeon's cheirsidc . However, as will be explained in greater deta il in later cha p ters, by d oing this, the surgeon mus t exp ose the tooth mu ch more widely, place su rgical packs and a im for healing ' by secondary in tention' onl y. Additionally, the reliability of the bonding at th is later d ate is m uch poorer than when per formed at the time of su rgery (Becker et al, 1996). For the pu rpose of bondi ng ort hod ontic bracket s to erupted teeth in day-to-d ay practice, the teeth ar e first cleaned using a rubber

cup and pumice. The aim of this p roced ure is to remo ve extraneous materials, which includ e soft plaque, d ried saliva, or gani c and chemical staining an d d epo sits that adh ere or adsorb to the ena mel prisms and tha t may pre vent penetration of the acid. Once these are rem oved , the enamel su rface becomes vulnerable to the orthophosph oric acid etchant, which is the key to successfu l adhesion of the attachmen t By contrast, new ly exposed im pacted teeth are com pletely free of these extraneous ma terials. Their only covering is Nas my th's membrane, which is ma de u p of the enamel cuticle and the red uced enamel epithelium, and is about 1 JIm thick. This ap pears to presen t no barrier wha tsoever to the etching effect achieved by the app lication of o rthophosphor ic acid (Becker et al, 1996). Accordingly, there is no ad vant age to be gained by pumicing these teeth as part of the bonding proced ure . Rathe r, the reve rse is the case. To permit the introd uction of a hand piece and rub ber cu p or a sma ll electric toot hbrush o r hand bru sh, exposure has to be considerably broade r for p rophylaxis to be effective. It is d ifficult to con trol these im plements du ring the bru shing exercise, and, as a d in.r. et conse quence, the bru sh or cup tra umatizes the exposed. bone an d soft tissu es. Th is generates renewed bleeding, wh ile giv ing rise to a di spe rsal of the pumice over the immed iate su rg ical field .

THE TEAM APPROACH TO ATIACHMENT BONDING This episode p rimar ily re presents an adjun ctive surgical p roced ure, wh ose
SURG ICAL EXPOSURE OF IMPACTED TEETH

pe rform ed in the ora l surgeon' s operatory. Howeve r, the o rthodon tist need s to p repare a sma ll tray o f ins tru ments an d materia ls tha t are n ot norm ally availab le in the operating room , together with a prepared auxiliary sp ring, which may ha ve been fabric ated at a p revi ou s visit for the p ur pose of applyi ng a d irect iona l fo rce to the impacted tooth, such as a 'ballts ta' (Jacoby, 1979), a flexible pa latal arch (Becke r and Zilbc rman, 1975, 1978) or a labial s pring auxilia ry (Korn ha user et al, 1995) (see Chapter 6). The ins tru ment tra y should contai n the following items:

Instruments • a fine plie r (e.g. a Begg wire-be nding plier) • a fine 'w ire cutter • a reverse-action bracket- hol di ng tweezer that is closed when no t held and releases when its handles are lightly squeezed • a ligature d irect or • a mosquito or Matthieu force ps • a fine sca ler

Materials • etchi ng gel • com pos ite bo nd ing material, pre ferably in the form of a no-mi x pa ste and catalyst, wh ich is probably the most ma nageable ty pe of bond ing met hod that may be used in these spe cial circumst an ces • ap plicators (w ood sticks, fine brushes etc.) Attachments

• eyel ets we lde d to band material, ba cked wi th s tain less steel me sh; these should be cu t and tr immed into pa tches of var ious sizes, but no t Luger than the base of a small bracket • cut lengths of de ad sof t stainless steel liga tu re wire of ga ug e 0.011". • elastic thread, elast ic ligatures of various sizes o r clast ic chain The sur geon reflects a mucope riost eal flap ove r the impacted tooth and removes the interven ing bone, which is usually very thin and easy to peel with a scalpel blad e. The den tal follicle is removed from the target area

immediately ove rlying the crown, and the resultant exposure is not widened mo re than is necessary to sa tisfy two basic req u iremen ts (Figs 3.8a,b): (a) to p rovide enough enamel surface to accept a small atta chm ent ; (b ) to d o so in an a rea wide en ough for adequ ate ha emosta sls to allow the bond ing p roce dure to ta ke place without fear of contami na tion. The surgeon then moves to the ot her side of the operating couch, in orde r to take over the entire responsibility for maintaining the enamel su rface free of blood and sa liva throughout the cri tical bonding phase which is, after all, the point of the en tire exercise! Un der the cond itions of exposed and oozing soft tissue and bo ne surfaces, th e su rgeon will generally need to use a regul ar suction tip and a second very fine tip in th e form of a canula No. 14 or 16, in ord er to maintain a bloodless field of opera tion for the bonding p rocedure. Occasionally, a pe rsis ten t bleeding point from the bo ne surface may require ei the r pressure from a blunt ins tru ment or the app lication of bone wax to occlude the tin y ve ssel. Soft tissue bleed ing ma y be controlled w ith an electrocau tery, a hot bu rn isher or, occasionally, ligation of the vessel. Bleedi ng in the folli cu la r spa ce is bes t a rrested w ith the use of light p ressure from a strip o f ga uz e, which may be left in place u nt il su turing is begun. The orthodontist proceed s di rectly to rinsing the tooth surface with sterile saline from a large syringe, through a wide-bore needle, to d isperse any blood from the tooth su rface, and the saline is eva cuated thro ugh the broad suction tip, op era ted by the su rgeon. The fine suction tip is then s ubs titu ted and is made to hover ove r the entire expose d crown, close to the tooth surface, with the aim of d rawing air ov er the clean ename l. Th is achieves effective d rying . Liqu id etcha nts should not be used in the exposed surg ical field (Kokich and Mathews, 1983), since it is d ifficult to p reven t their sp read to the exposed so ft tiss ues and bone surfaces an d, perh aps mo re im po rta ntly, to

38

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(d ' Figure 3.8 (ill The crown of an imp.Ktt",) ca nine is ('X~. usi ng ... wide fla p, but w ith remova l of minima l bone. The u n('xping fully replaced and su tured . (d ) The la bial s pring auxiliary I" up. St.... n in its p.l"",i\'<.· p..."ition in k ). h.1S been turned inwa rds toward s the palate and secu red 10 the stain les s ste....·l li);,l lur ... p ig t.liL

the area of the cemc nto-enamel junction and the too th a ttach me nt Mea. Etchn nt is be st applied as a gel on the end of a fine w ooden too th pic k applicator (non-medicated ), left in p lace for 30 seconds and then d ra w n off by the surgeon, through the fine suctio n tip, before the su rface is rin sed again w ith sa line to remove the last traces of the acid. Continua tion o f the usc o f the fine tip will d ra w air over the su rface of the crown of the too th until dessicat ion is achieved, and the typical w hi te ma tt a ppe ara nce of the etc hed

s urface w ill then qu ickly ap pear. Th e surface is now ready for bondin g. Ma ny practitioners may be concern ed ab out the adequacy of the dessica tion , a nd ma y al so prefer to be s ure th..at no sa lt crystals rema in from the d r ied sa line . Experience s hows such worries to be g rou nd less. Never the less, to alla y the m, a final rinse w ith at omized wa ter fro m the triple syringe may be followed by a fine compressed air s trea m to achieve the a p pro priate degree of dryness of the enamel surface. For thi s to be success-

SURGICAL EXPOSURE OF IMPACTED TEETH

fu l, the com pressed air stream must be very gentle, to avoid sp lashing up blood from the surgical area , wh ich will contaminate the ena mel and cause bond failu re. The prepared eyelet attach ment has a pliable base. An attachment of appropriate size sho uld be se lected and ad apted between the plier and the gloved hand of the or thodontist, to fi t the target bonding site. A cut length of 0.0 11~. (0.275 nun) dead soft stainless steel ligatu re wire is threaded thro ugh the eye let, and, wit h the use of the mosquito or Matthieu forceps, is twisted into a med iu m tigh t and firm pigt ail, wh ich shou ld swing freely in the eye let. Strictly, any type of bondi ng agen t may be used, includ ing ligh t activated and chemically activated system s. Our ow n p reference is for a chemically activa ted ' no-mi x' system, su ch as Rely-a-Bond" (Reliance Orthodo ntic Prod ucts, Inc, Itasca, IL) or Righ t-On " (TP Laboratories, Inc, Laporte, IN ). In this system, the attachment is seized in the reverse-action bond ing tweezer, and its mesh base is pa in ted with the catalys t liquid . A sma ll quan tity of bond ing pa ste is placed on the attac hment, wh ich is d elivered to the ope rating area. The etched ena mel is checked for dryness once again, and then painted with th e liqu id catalys t. The attachment is pressed firm ly into p lace on the crown of the tooth, until paste oozes from underneath the mesh base. Even withou t wait ing for initial sett ing, the viscosity of the paste will ho ld the attachm en t in place withou t the nee d for any su pport, an d carefu l fine-tip suction in the su rround ing are a is p robabl y all tha t is needed to gua rantee bond ing success. Many operato rs prefer to usc th e mosqu ito or Matth ieu forceps to carry the att achm ent to its place and to hold it there unt il setting has occurred. Un fort una tely, the freeing of the attachm ent from th e forceps is achiev ed by changing the hand g rip and unl ocking the ratchet tha t ho lds the hand les closed . These mano euvres prod uce cons iderable jolt ing and jarrin g of the attachme nt, which may seri ously u ndermine the streng th of the fresh ly crystallized bond. Accordingly, it is better to use the reverseaction bond ing twee zer, wh ich m ay be much

mo re gen tly disengaged immed iately the att achm ent is in place and , preferably, before the initi al se t has occu rred . If continuo us press ure is desired during the setting period, the ligatu re di rector m ay be substitu ted for the tw eezer an d placed with its notch engaged ast ride the eyelet loop and pressing against it. To free the ligatu re d irector, once se tting is comp lete, it is merel y wit hd rawn in the d irection of its long axis, w ithout generating any und ue lateral jarring. A sho rt time lapse of a few minutes shou ld be allowed be fore the new ly bonded attachm ent is tested for strengt h, and th is should be d one befo re the flap is resu tu red. The replacement of the flap will h ide the impacted tooth from sight once aga in, an d it will become evident in later stage s that it is pruden t to ph otog raph the tooth and its atta chment befo re closure is performe d (Fig. 3.8). By photographically recording its posi tion, subsequent decisions related to d irection of orthod ontic traction may be more reliably mad e. As part of the or iginal orthodontic treatment plan, an accurate radiographic assessment of the po sition of the impacted tooth will have been ma de and an app roach to its orth odontic reso luti on formul ated . With the impacted too th now in full view, the orthodontist mu st confirm how it is to be moved to its place. If this is to be per formed in a di rect line to the prepared place in the dental a rch then the p igt ail ligatu re will be swivelled on the eyelet until it po ints in that d irection. The surgeon will then su tur e the flap back ove r the wire, leaving its end freely p rotr ud ing through the cu t and su tu red edges. As we sh all d iscuss with regard to a palatally im pacted max illary canin e (Chap ter 6), some times the direction of the traction cannot be pointed straight to the labial archwire, becau se o f the proxim ity of the roots of adjacen t tee th. In this case, th e wire may initially need to be drawn vertically do wn war ds, tow ard s the tongue. To ach ieve th is, the pigtail cann ot be d rawn th rough the su tu red edges of the flap, bu t rather must be taken through the middle of the pa lata l area. T~is means tha t the reflected flap mu st be d ivided into two halves, one on eithe r side of

40

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - - - - - - -- - - - - -- -=---=---=------'--the pigt ail, to accomo d ate th is (Fig. 3.8e). A bette r alte rnat ive is to pass the pigtail through a small pinhole in the palatal mucosa, prior to rcap prox imation and s utu ring of the flap . When sutu ring is comp leted an d the pa latal area co mpletely closed off, the orth odontist should shorten the pigtail and tu m it up into a ho ok o r circle, to be a tta ched to a n act ive

palatal arch, ballista o r labial spring auxiliary (F;g.3.8d ).

The application o f traction sho uld be immed iate , regardl ess of which method is used. It w ill be appreciated that later manip ulation of the ligature pigtail as it passes through the soft tissues is very unp leasan t and even

painful for the pa tient. While subseq uent manipulation may only be necessary for two or three ad d itional adju stment visits bef ore the tooth is erupted and the p igtail free of the soft tissu e, the re is m uch to be said for the first of these bei ng fu lly exploited w ith the application of appropriate traction while a local anaesthetic is ope rational. The reliability of the bond ing p roced u re under the circu mst ances described here has been shown to be extreme ly high (Becker et al.-19% ). In the pas t. however, bon di ng in the presen ce of an open and bleed ing wound . involving bot h soft and hard tissues, wa s considered s tro ngly con traind icated . since it was thou gh t to be inco ns istent with the attainme nt of a d ry and uncontam ina ted field . Th is att itude, on the pa rt o f the orthodontist. was p robab ly nurtu red more ou t of a ret icence to be pr ese nt at the surgical episode th an ou t of any experience of a h igh incidence of failure in attach ment bo nd ing at th at time. It is important to em phasize the need to properl y ad apt the base of the attachment to the shape of the recipie nt su rface of the cro wn of the tooth . Th us the use of standa rd b rackets with ' anatom ical' bases, as s upplied by the ma nufac turer, we re shown by Becke r et a l (1996) to fare consid erably bette r in the midbuccal position o f the impacted tooth (80.6%) tha n on an y othe r su rface, pa rticu la rly the pa lata l s u rface, whe re the chances of its su rviva l are 58.3°,1" - a failu re rate of almost 1 in 2! Better s till, and at a 96.7% lev el o f reliab ility, a small attachment (suc h as an ey elet) on a pliab le base, prope rly and ind ivid ua lly

adap ted to the form of the recipient site, will allow the or thod ont ist to wor k w ith the greatest de g ree of co nfide nce. It w ill be apprecia ted th at the presence of the o rthodontist at the su rgical interventi on has much to co mmend it. In the first p lace, the ort hodontist is able to see the exact pos ition of the crown, the d irection o f the long axis and the ded uced loca tion of the root apex. The height o f the too th and its relati on to ad jace nt roo ts may all be note d, and the orthodontis t may p lan the strategy o f its resolu tion by d irect visio n. The orthodontist will be in a position to deci de exactly whe re he or she would like to see the attachment placed from the mechanotherapeutic point of view, and will bo nd it there. It is not fair to expect the ora l su rgeon to be aware of how different atta chment positions may affect the orthodontic or periodontic p rognosis, and neit her shou ld it be expec ted of him or her to be sufficient ly experienc ed wi th the bonding tech niq ue to do this. For m ost or al s u rgeons, bond ing is no t a procedure th at they norma lly carry out. The p resence of the or thod ontist allows for bonding to be pe rformed efficien tly, with the su rgeon an d nu rse maintaining ha emostasis and the necessary d ry field .

REFERENCES Altuna G, Walker DA, Freeman E (1995) Rap id ortho pe dic lengthen ing of the mand ible in pr imates by sagittal sp lit osteo tomy an d dis traction osteogenesis : a p ilot stud y. int ] A dult Grtnod Or tlwgnath Surg 10: 59-64 . An d reasen 10, And reasen FM (1994) Textbook and Color Atlas of Traumatic Injuries to the Teeth. Mun ksgaard , Copenhagen. Becke r A, Shochat S (1982) Su bme rgence of a de ciduous too th, its ramification s on the de ntitian an d trea tmen t of the res ulting malocclu sion. Am J art/lOll 81: 24()-4. Becker A, Zilberman Y (1975) A comb ined fixed -removable approach to the treatment o f

SURGICAL EXPOSURE OF IMPACTED TEETH

impacted maxillary canines. / Clin O rthoaont 9, 162- 9.

41

Becker A. Zilberman Y (1978) The palatally impacted can ine: a new app roach to its treatment. Am / Orthod 74: 422- 9.

Kohavi D, Becker A, Zilberma n Y (1984a) Surgical ex posure, orthod on tic movement and final toot h positio n as factors in pe riodontal breakd own of treated pa latally impacted can ines. Am / Orthod 85: 72-7.

Becker A, Kohavi 0 , Zilberman Y (1983) Periodonta l statu s follow ing the align ment o f palatally im pacted ca nine teeth . Am / OrtJlOd 84, 332-6.

Kohavi D, Z ilberman Y, Becker A (1984b ) Periodontal status following the alignment of buccall y ectopic maxillary can ine teeth . Am / Orthod 85 : 78-82.

Becker A, Shpa ck N, Shteyer A (1996) Atta chm en t bo nding to im pacted teeth at the time o f s u rgical exposure. Eur / Orthod 18: 457-64.

Kok ich VG, Mat hews DP (1983) Surgical and orthodont ic management of impacted tee th. Dent cu« N Am 37: 181-204.

Blackwo od HJJ (1958) Reso rpti on of en amel and d en tine in the uneru p ted tooth. Oral Surg Oral Mel! o-« Poth 11: 79-85. Boyd R (1982) Clinical assessment of inju ries in ort hod ontic mo vemen t of im pacted teeth . I. Method s of atta chment. Am / Orttiod 82: 478-86. Boyd R (1984) Clinical assessment of injuries in orthodon tic move men t of impacted tee th . II. Surgical reco mmendations. Am / OrlhOO 86: 407-18. Crescini A, Clauser C Giorgetti R et al (1995) Tunnel traction of intraosseou s impacted maxillary canines: a th ree-year pe riodontal follow-u p. Am / Orinod Dentofac a rt/lOp 105:

464-76. Oi Biase DO (1971) The effects of vari ations in too th mo rpho logy and position on eruption. Dent Pract Dellt Rec 22: 95-108. Heaney TG, At herton JD (1976) Peri od ontal problems associated with the sur g ical exposure of unerupted teeth . Br / OrtllOdol1 t 3: 79-85. Iliza rov G, Dev ya tov A, Kamcr ln V (1980) Plas tic reconstru ction of longitu d inal bone defects by me an s of compress ion and s ubseque nt d is traction . Acta Chir Plast 22: 32-46. Jacoby H (1979) The ballista spring syste m for impacted teeth . Am / Orthod 75: 143-51.

Korn hauser S, Abed Y, H ara n D, Becker A (1996) The resol utio n of p alatally-impacted can ines using pal atal-occlusal for ce from a buccal auxilliary . A m / Crthod Dt'lltof ac Orthop 110: 528-34. McBride LJ (1979) Tract ion - a su rg ical/ orthodontic p roced ur e. A m / Ortltod 76: 287-99. McDonald F, Yap WL (1986) The surgical exposure and application of direc t tr action of unerupted teeth . Am / Ort1lod 89 : 331-40. Odenrick L, Modeer T (1978) Periodontal sta tus following su rgical-orth od ontic alignment of impacted tee th . Acta U dontol Scand 36: 233-6. Vana rsdall RL, Com H (1977) So ft-tissue managemen t of labially positio ned uneru p ted tee th . Am / Orthod 72 : 53-64. Vermette ME , Koki ch VG, Ken nedy DB (1995) Uncov ering labia lly impacted tee th : apically positi oned flap and close d -eruption techniqu e. Angle Ormod 65: 23-32. Wisth PJ, Nord ervall K. Boe O E (1 976) Periodontal status of orthodonttcally treated impacted max illary canines . A I1Kle Grtliod 46: 53-7. Wong-Lee TK, Won g FCK (1985) Maintain ing an idea l too th-gingiva relationship whe n exposing and ali gn ing an impacted tooth . Br / Or/hod 12: 189-92.

4 TREATMENT STRATEG Y

CONTENTS • Orth od on tic trea tme nt duration • The anchor unit • Elas ti c ties and mod ul es versus auxiliary sprin g s • Mag nets

ORTHODONTIC TREATMENT DURATION The opening o f adequate space in the arch may ini tiate movemen t in an unimped ed im pacted tooth, which may slart mov ing in the ap pro pri ate d irection, so metimes quite quic kly. By the tim e the sp ace is of sui table size and the a rran gem ents for surgery have

been made, a new per iapical radiograph may show much positive change in its position an d lead the clinician to believe that spontaneous eruption will rende r the surgery unnecessary. If the eruption is likely to occur imminently, or at IC<Jst with in a reasona ble per iod of tim e, then there is meri t in waiting for this to occur . If, on the other hand. er up tion will take many months then the orthodontist must weigh the ben efits of avoid ing surgery against the d rawbacks involved in leaving orthodontic ap plian ces in place for all this time or in removing them before all the teeth are in th eir appropria te places. Orthodon tic ap pliances raise the level of vulnerab ility of the tee th to cari es and of the periodontium to inflam mati on - the longer they are in p lace, the greater the risk. Remov ing the app liances

• AUachments

before time ru ns the differen t risk of having to later repl ace them to correct a ma lposition o f the new ly erupted and ers twhile im pacted too th . In order to so lve this d ilemm a, the clinician may elect to . ad vise s urgical exposur e and orthodon tic traction. thereby expediting the eru ption of the tooth an d com pleting the treatment in a very much shorter time frame. When orthodontic treatment ha s provided space, and surgery is undertaken to remove a physical obstacle, a simila r d ilemm a may occur. In the absence of the obst acle, the impaction is po ten tially resolvable, unaided by furthe r treatmen t. However, the surgical interven tion involved in removing the obstacle offers the opportu nity of access to the un eru p ted tooth . Subs equ ent healing of the wou nd will deny tha t access, and, in the event that eruption doc s not tak e pl ace, a secon d su rgica l intervention in the same area will be necessa ry and mu ch time w ill ha ve been wasted confirm ing that spon taneou s eruption will not occu r. Clearly, then, the time factor must not be ignored . Orthodontic appliances are in p lace, and pe rha ps the sp ace in the arch is unsigh tly . Without question, orthod ontically aided eru pt ion will speed up

44

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

the resolution enormously, and. this being so, the patient' s best interests arc to be served by inclu ding this op tion am ong the factors to be considered at the p lannin g stage. Whe n the existence of an impaction is onl y a sma ll pa rt of an overall complex malocclusion , the tim e factor becomes more critical. It is quite conceivable and reasonable to estima te that a given overall p roblem, alone, ma y require a z-year treatment period. The comp lete alignme nt of an awkwardly placed im pacted too th may add a further year or morc to this period. To permit the luxury of a ' wait-and -sec' pe rio d is to ad d this time to an al ready extended a-yea r period d uring which appliances arc worn . Wh ile the o rthodon tist ma y we ll be reward ed by a much im proved pos ition of the impacted tooth, the state of health of the teeth and pe riodontium m ay d epr ive the achievement o f all me aningfu l content.

THE ANCHOR UNIT At this jun ctu re, it is not the intention to go into the details o f appliance therapy. This will come later, as the different grou ps of Impacted teeth tha t are seen in practice are dea lt wit h. Howeve r, so me ge neral principles are app rop riately given here. For mo st malocclusion s, quality treatment is best pro vided by the usc o f on e or othe r of the recognized fixed appliance treatment techn iques. If the d en ial arc hes are cor rectly relat ed and adequa te space is pr esent then the teeth ar e initi allv ' levelled' to a labia l archwire of standard ized ar chform and a given coeff icien t of ela sti city . Later, heavi er rou nd or rectangular arch wires are substituted to perfor m roo t move men ts that will pave the way to achieving an optima l result. Incorrectly rela ted dental ar ches will benefit from the use of othe r ap pliances, s uch as hea dgears, fu nctional appliances and intermaxillary elastics, p rior to or in ad dition to the fixed applia nces, while space may be provided by the extraction o f teet h or by expanding the arches mesic-distally or laterally. When d eal ing wi th a ma locclusion tha t

incor po ra tes an im p acted too th, mod ifications must be made to thi s procedure. Unlik e other teeth in the mouth, th e im pac ted too th may be severely d isp laced from its norm al position in all three planes of space, an d much anchorage will be expended in bringing it into alignmen t. Accordingly, it is necessary to d evelop a rig id ancho r base against which to pit the forces required to reduce the im paction. At the age at which an impacted ma xillary canine is treated, the fu ll permanent d entition (wit h the exception of thir d mol ars ) is almo s t inv a riab ly p resent. Acco rd ingl y, a full y mu ltibra cket ed appliance should normally be placed and the ent ire de nt ition treated, through the stages of levelling and the op ening of adequate sp ace in the arch for the impacted tooth . A heavy and more rigid archwi re is then p laced in to the bra ckets on all the teeth o f the fully align ed and comple te dental arch. The aim o f th is is to pr ov ide a solid an chorag e base (Kokich and Mathews, 1993) thai will no t allow d is tortion of the arch w ire to occur as a result of the forces tha t will eve ntually be applied to the im pacted too th afte r its exposu re. The effect on th e an chor unit of forces d esigned to resolve a grossly di sp laced canine should not be underestima ted , parti cu larl y if the y are applied for an ex tended peri od . By contrast, at the time whe n an impacted central inciso r requires treatment, only first perm anent molars and th ree pe rm ane nt inciso r tee th are p resent. Accord ingly, alternative mean s of making the ap p liance system rigid must be employed before ligh t forces ma y be applied to the imp acted tooth, in order no t to comp romise the remaind er of the dentition.

ATIACHMENTS To be in the position of be ing able to influence the furore development of an im pacted tooth, it is necessary to pla ce some form of attachmen t on the too th. These attachments ha ve changed over the years , reflecting the advances made in the field of d en tal materials.

TREATMENT STRATEGY

45

Figure a.I L.1S!'><)

wire en circling th e ru-ck of an im pacted can ine.

Lasso wires In the years prior to the mid-1960s, a lasso wire (Fig. ·tt) tw isted ligh tly aro und the neck of the canine h ad been employed widel y, and was used in ou r earli er cases in th e initial stages. It will be readily appreciated that the shape of the crown of a tooth is such that its narrowest d iame ter is at the CEl, which is where the lasso wire will inevitably sett le.

Th is will res ult in irritation of the g ingiva and prevent reatt achmen t of the healing tissues in this vital area. It has also been reported that external resorption an d ank ylosis have been produced in the area of the CEl followin g employment of this method (Shapira and Kuftin ec, 1981). Given the excellent alternatives th at are available tod av, the lasso wire is obsole te. '

Threaded p ins

Figu re ~.2

Threaded pins set into prepared holes. drilled and tapped into the enamel and dentine of the su rgically exposed canines.

Severa l systems o f threaded p ins (Fig. 4.2) have been avai lable for many yea rs. Their specific purpose is to p rov id e retent ion for an ama lgam or com posite core, to allow the p rovision of a cast crown in a severely broken d own tooth. These threaded p ins may also be used to p rovid e the attach ment for an impacted too th. This is a method that was used in the pa st (Kettle, 1958; Becker and Zilberman, 1978), bu t h as bee n totally superseded. Its d isadvan tages in clud e the fact that it is dentally invasive, necessitating a subsequent restora tion. Given th e dif ficulties of access to many im pacted teeth and the d esir ability of limiting su rgical exposu re as m uch as possible. the orient ation of the long

46

------------"-'-----'--'-'--------=-----------

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

ax is of the tooth may be d ifficult to determine, and the drilled hole may inad vertently en ter the p ulp - un eru p ted teeth often have large pulp chambers! Neverth eless, the method is st ill in use in some q uarte rs (Kokich an d Mathews, 1993).

Orthodontic bands Preformed or thodontic bands largely replaced the lasso wi re, and clinical experience wi th them sh owed them to be considerably more co m pa tible with ensuring the health of the periodontal tissu es . As with the lasso wire, however, the u se o f a ba nd dictated the very wide surgica l clea rance of tissue on all sides of the tooth (see Fig. 6.32c), in order to ade-

FiguO' 4.3

As the impacted tooth is about to eru pt, the high profile Siamese edg ewise bracket has fenestrated the swollen gingival tissue.

quately control haemorrhage aroun d the crown and to a void contamination from oozing blood insid e the cement-filled band at the time of placement. Since the introd uction of enamel bonding, all of the abov e- me ntioned ea rlier methods have become obsolete . The em ployment of the ad d-e tch com posite bonding tech niq ue to the crown of a too th has m uch merit (Gensio r and Strauss, 1974; Nielsen et al. 1975), notably in terms of the simplicity and reliability o f the bond. Its most important advantage is that it req u ires rela tively little exposed surface of enamel for it to be successful - a fact that ma y contribute greatly to the subsequent periodontal health of the tre ated resu lt. It is p resent ly witho ut d ou b t the meth od of cho ice from almost every p oin t of view, and it shou ld repla ce oth er methods in virtually all drcu rn stances.

Standard orthodontic brackets As far as the actual choice o f ty pe of attachment to be placed on impacted teeth is concerned, there ar e several sa lien t po ints to conside r regarding the Impac ted too th when compared with an erupted tooth tha t requ ires to be brought into its position in the dental

arch. Edgewise, Begg and othe r orthodontic br ackets represent sophisticated designs of attachme nt tha t enable the orthodon tist to perform any type o f movem en t on a tooth in the three planes of space. It is not possible, however, to ach ieve mo re th an tipping, ex trusion and some rotation until the bracket reaches and fully engages the main arch wire. In other word s, its efficacy up to tha t point is no gre ater than th at of a simple eye let (Becker et al, 1996). The base of a convention al b racket is wide, rigid and difficu lt to convert to the sha pe of another pa rt of the tooth 's sur face other than the mid-bu ccal, for which it has . been designed . Th us compos ite bond ing elsewhere on a tooth is ver y like ly to lead to failure (see Fig. 7.6) (Becker et al, 1996). The standa rd ort hod on tic bra cke t in an y technique is relatively large, possesses a wide, high an d sha rp pr ofile, an d, even whe n placed in alternative pos itions on the too th, by force of circumstan ce at the time of surgery, it is inevit ably dee ply sited in the surgical wou nd . The bracket' s shear bu lk creates irritation as the tooth is later d rawn thro ug h the soft tiss ues, particularly the

47

TREATMENT STRATEGY

mucosa (Fig. 4.3). A ligatu re wire or elastic th rea d tied to it must also originate deep in the wound, and w ill be s tretched across the rep laced flap tissue towards the labial archwire. Th is increases the po ssibilit y of interference with the inves ting tiss ues, and lead s to inflammati on and to probab le pe rmanent pe riod on tal d am age. As the d isp laced too th moves toward s its place in the arch, exuberant gingival tissue bunches up in fron t of it, which will also lead to imp ingeme n t by a conventional o rthodontic bra cket. The existe nce of the exuberan t ging iva l tiss ue in advance of the too th can often cause ' p inching' between it an d the teeth in the arch immediately adjacent to it. This is less likely to occu r if a deli be rately generous space is p rovided in the arch for the tooth, and this precaution ma y avoid unnecessary peri od ont al d am ag e. Because of the close p roxim ity of an impacted tooth to the roo ts of adjacent tee th, it is often impossible to bond a conventional bracket in its p rope r p lace on the too th. Accordi ngly, the brac ket ma y have to be sited on the palatal su rface of the too th, where its prefor med base is contoured very d ifferen tly from the shape of the recipient (pa latal) a rea o f the tooth, comp romisi ng its retentive p roperties .

Figu re 4.4

Eyelets welded to a pliable band material base, backed by steel mesh.

A simp le eyelet An eyelet, we lded to band ma terial w ith a mesh- backing (Fig. 4.4), is soft an d ea sy to contou r, ma king its ad aptation to the bondi ng su rface mo re accurate, which ma kes for s uperior reten tive p roperties. Its relatively sm all size and lo w profile mak es the midbuccal pos ition of severa l of the more awkwa rdly p laced teeth cons iderably more access ible when compared with the p lacing of a conventional bra cket. Its modes t. low -profile, d imensions are also less irritating to the su rround ing tissues. For these reaso ns, a small eyelet is recom mended as the initial attachment, pl aced at the time of su rgery and removed only whe n the tooth has p rogressed to the point where it is in close p roximity to the archwirc. At tha t time, it should be substitut ed by the same type of sophistica ted b racket tha t is bei ng used on the oth er teeth th ereby pe rm itting the in itiation of the more intricate roo t man ipulations of the tooth (ro tat ing. uprigh ting and tor queing). We ha ve seen in Chapter 3 that there are importan t pe riodontal ad va ntages to be ga ined by full closure of the su rgica l flap at the end of the visit d uri ng which the surgical exposure is pe rformed. Thus the impacted too th is re-covered by the su rgical flap, an d is lost from sight, unl ess the impacted too th is fairly superficially p laced . The on ly manner in which contact may be maintained with it is through the agency of so me form of ligatu re wire, gold chain or clastic thread, which is att ached to the eyelet before it is bonded to the tooth . Since elasti c thread can only be tied once, it is not recommended for ,10 attach ment that is not clearly visible and accessible in the mouth . Gold chai n would appear to be unnecessaril y sophisticated, although it is undoubtedl y su itable and su fficiently strong for the pu rpose. The usc of a st ainless s teel ligature is fa r ea sie r from ev ery point o f view, and is read ily at hand in the orthodontic and surgical ope ra tory. Such a ligat ure is passed th rough the eyelet and twisted into a lon g bra id with artery fo rceps be fore bond ing is und ertaken. The b raid ed wire or p igtail

48

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

han gs loosely in the eye let until after bonding and resu turing have been comp leted, and it shou ld be of su fficient su bsta nce for it to be rolled u p into a loo p tha t w ill not eas ily be unravelled by the application of the extru sive force. On the other hand, it must no t be so th ick that the effort that is needed to form the loop will seriously test the bond strength of the newly p laced attachment. In p ractice, the

use of a dea d soft sta inless steel ligatu re wire of 0.011" or 0.012" ga uge is ge ne rally the most suitable. It has been recommended that the p igtail be braid ed in such a way that each two or thr ee tu rns of the b raid arc followed by a small loo p, then two or thr ee more turns, another loop, and so on. In this wa y, the braid comp rises a convenien t chain of loo ps, which may be shorten ed as ne cessary by cu tting off the excess, while exploiti ng the loo p closest to the gi ng iva l tissue (Ziegler, 1977). However, ' roll ing up' the term ina l loop of a s imply twis ted stai nless steel ligature as the tooth p rog resses is simpler and ' u se r-friendly' .

ELASTIC TIES AND MO DULES VERSUS AUXILIARY SPRINGS At first glance, elastic ties of one sort or an other prese nt the o rthodont ist wit h the most convenie nt mea ns of applying ligh t forces to a too th, with a good range of action . Howe ver, their u sc is usually far more d isap poin tin g than one may ini tially realize. The manufacturer' s spool of elastic thread usually comes in the form o f fine hollow tub lug, wh ich is easier to tie th an a solid thread. Most orthodontists tie the thread wi th a simple knot that, when tying string, will not u nr avel. When tyi ng elastom cn c thread, howev er, the kn ot tends to loosen , and much of the ori ginal force of the tie will be lost in th is loose ning. When under ten sion , all the mat erials u sed to make this elastic thread su ffer a high deg ree of force decay, which is very rapid an d very significant. The force levels of chai ns of various lengths are kno w n to decay to below th e force required for tooth movement, in a pe riod of

Figure 4.5 A direct ric us ing a vl'ry short length of elastic thread.

between 1 and 3 wee ks, depen di ng upon the amo unt of tension initially applied (Lu et al, 1993; Stori e et al, 1994). Na turally, a shorter pi ece of stretched elastic (Fig. 4.5) will hav e a very sho rt range, and ru ns the risk of a pplying an initia l excessive amount of p ress ure if the tie is good - or no effective pressure if the tie loosens. The immatu re pe riodontal membrane of the rece ntly exposed tooth and the s trength of its bonded attach me nt cou ld be severely tes ted . In the case of an unerupted too th close to the line of the arch, traction a pplied d irect ly fro m its attachme nt to the arch wire will ge nerally be very inefficient, req ui ring freq ue nt ch anges and prod u cing on ly a ve ry slo w res po nse. For all pract ical pur poses, it is imposs ible to measure or control suc h a force. It is prude nt to u se mo re distan t sites from whi ch to apply tra ction to the un erupted too th, in ord er to in clud e a greater leng th of elastic thread to increase the range of the traction force and thereby its effectiv en ess in mov ing the tooth over a longer pe riod of time. To do this, the elastic th read needs to be stretched to the target area on the archwtrc, th rou gh the agency of a loop be nt in to the archw ire a t that poi nt. The thread ma y then be tied back to the hook on the molar tu be of the same side, with care being taken to insert a stop in the erchwlre, mesial to the tube, in

49

TREATMENT STRATEGY

ord er to p revent mesial movement of the molar. As a general ru le, elast ic thread sho u ld be used as the go-betwee n connect ing the nonelas tic stL'C1 pig tail to a sim ilarly non-elastic and heavy archwire . If a ligh ter archwire is used then the tie sho u ld be mad e with a steel ligatu re - the arc hw ire pro vid ing the clastic d isplacemen t. In th is event, however, the d istortion o f the a rchwire will bring about an alter ation in its shape in bot h the horizontal and vertical planes, to p rod uce unwanted change in the form of the dental arch and an uneven occlusal p lane. The use of bot h a flexib le arch wire and an elastic liga ture (Shapira and Kuftinec, 1981) is coun terp roductive, since the elasticity of th e on e that exerts the stronger force will be effectively neutralized and will offer no physical advantage over a steel ligature, while the d isplacem ent of the wea ker element will be the only factor th at is active in moving the teeth. In general, orthodontis ts use elastic ligatu re to move teeth by first elonga ting the material and tyi ng it between two dental ele men ts. Once tied, a na tu ral reco il is exerted along its long axis, pulli ng the den tal elements

towa rd s one another . The amoun t of elas ticity in this d irection is lim ited and , as pointed out above, d ecays rap id ly. However, the lateral d isp lacem ent of an elo ngated elas tic thre ad p rodu ces a po ten tia lly g reat er ran ge of movement, with in su itable ort hodontic force levels, than does a longitudinal d isplaceme n t. Th is p rin cip le may be applied to moving teeth that lie at a d istance fro m the main a rch mo re efficientl y an d wit h controlled an d meas u rable forces (Fig. 4.6). Given a litt le thought in the p lanning o f their use, elastic ties, cha ins and modules are extremely helpfu l in many situ ations aris ing because of the p resen ce of impacted teeth. However, properly designed sp rings, auxiliary to a heavy ba se ar ch, are usually more efficien t, since their abili ty to deliver a measured an d con trolled for ce is good, the force decay is lower, the variety of metallic alloys available for sp ring fabrication is broad, an d their range of act ion may be very wide and their di rection accurate. These will be illustrated in the d iscussion of cases as they pertain to the ind ivid ual gro ups o f tee th in the succeed ing chapters.

(h)

Figu re ~ . 6 (a) The 's lingshot' elastic. A pala tatly impacted canine has bee n e ru pted into th e pala te [see Cha pte r 6). The clastic module, placed bet wee n the br
50

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - -- - - - - -- -- - - - - - - - - - u late tha t this may im prove the final pe n odon ta l con diton of the teeth, since 'e rup tion simulates a nonnal eruption process' . How e ver, given tha t (a) the tooth m ust nevertheless initially be exposed. surgically, (b ) the magnet m us t be bonded to it, (c) the flap m ust be replaced a nd healing m ust occu r, and (d) the tooth m ust then pass thr ough the tissues wit h this rel a tively la rge ' backpack',

Figure 4.7 Tht.' 'backpac k' magn et. (Co ur tesy of A Va rdfmon.]

MAGNETS Ra re earth magnets we re de veloped 40 yea rs ago, bu t only more recently have they been developed to the point w here their red uction in size, w ith the introd uction of lanthanide

alloys, has provided the possibility of applying suitable forces that ma y be exploited in the present context. Vardimon et al (1987) and Sandler et a1 (1989) ha ve recently presented

succes sful clinical results of the treatment of im pacted teeth in h umans.

The magne tic attracting force that exists betwee n the two magnets is inversely propo rtional to the square of the distance between them . Th is mea ns that a magnet s ited on the a pplia nce must be placed dose to the magn e t that has bee n bon d ed to the d isp laced too th (Fig. 4.7) a nd that a grossly di splaced tooth may requ ire tha t the loca tion o f the ap pliance ma gn et be resited from time to time, in line w ith the p rog ress of the too th. The forc es generated arc centripetall y orie nta ted, a nd it is po ssible to design their a pplication to move the u nerup ted too th in all th ree plane s of space from the very beginni ng a nd be fore the too th e rupts (Va rd imon et al , 1991). Th e no tio n tha t traction may be a pplied w ithout the need to tra il a wire through the soft tissues of the palate, appeals to Va rdimon and Sandler an d their co-workers. Th ey spec-

th is claim may be d ifficu lt to jus tify in practice . The id ea is in deed 'a ttractive' (San dl e r, 1991), bu t it is no t a method tha t, at p rese nt, ca n u nequivocally rep lace the ma rc trad itional an d conven tion al metho ds de scribe d above (Inge rvall, 1993; Gi anell y, 1993; Rygh, 1993). Th e u se of mag nets for impacted teeth is in its ea rly de ve lopmental stages, a nd the me thod s tha t ha ve been d esc ribed appea r ra the r clu msy a nd in conv en ient (Da re ndelile r a nd Friedli . 1994). Th eir grea test d isad va ntage is the corrosion (Va rd im on, 1993) tha t occurs w ith their use in tissue a nd the, so far, u nsuccessful attempts a t their hermetic isolation . The use of magnets in this context an d with the present sta te of the art offers no advantages over traditional methods, an d p rovides little more tha n curiosity va lue . As these methods become mo re refined, particu larly w ith the ex pected fut u re development of even s maller magne ts of suffi cient p owe r, they may offe r so me rela tively minor ad vantages over the es tablishe d me thod s. wh ich could make the m more w idely acce pted for ro utine use in clinical p ractice.

REFERENCES Becke r A, Zil bcrman Y (1978) Th e pal atally im pacted can ine: a ne w a pproach to its tre atment. Am / OrtflOd 74: 422- 9. Becker A. Shpac k N, Shteyer A (1996) Attachment bonding to im pacted teeth at the time of surgical exposure. ElIr / Or/ hod 18: 457-64.

TREATMENT STRATEGY

Darcndelic r MA, Fried li 1M (1994) Treatment of an im pacted canine with ma gnets. I Clin Grthod 28: 639-43.

Sand ler JP (1991) An att racti ve so lut ion to u ne rupted tee th . Am I Ortlwd Dentcfac Orthop 100: 489- 93.

Cen sio r AM, Strauss RE (1974) The d irect bondi ng techniq ue applied to the ma nagemen t o f the maxillary impacted can ine. I A m D t'Ilt Assoc 89: 1332- 7.

Sandler PJ, Meg hji S, Mu rray AM et al (1989) Magnets and or tho don tics. Br I Orthad 16: 243-9.

Gianelly A (1993) The usc of magn ets in orthodontic therapy: pan el d iscussion. Eur / OrthOl.i 15: 42 1-4.

Ingervall B (1993) The u se of magnets in o rth od on tic the rapy : pan el d iscu ssion . Eur T Orthod 15: 421-4. Kettle MA (1958) Trea tme nt o f the unerupted max illary canine. fkn t Pract Dent Rec 8: 245-55. Kok ich ve, Ma the ws DP (1993) Surgical and orth od ontic managemen t of impacted teeth . Dellt cu« N Am 37: 181- 214. Lu TC, Wa ng WN, Ta mg Ti t Che n JW (1993) Force d ecay o f elastome ric chai ns - a serial s tudy. Pa rt 2. A m I Ortbod Dentofac Ort/lOp 1M: 373-7.

Shapi ra Y, Kuftincc MM (1981) Trea tme nt of imp acted cu spid s: the haza rd lasso. Angle Orthod 51: 203-7. Sto rie OJ, Rege ruu ttcr . F, von Fra unhofer JA (1994) Characteristics of a fluoridereleasing elastomertc cha in. AI/gle Orthod 64: 199-210. Vardimon AD (1993) The use of magnets in o rth od ont ic therapy: panel discussion. Eur I Orthod 15: 421-4 . Vardimon AD, Graber TM, Voss LR (1987) Hyg ien ic magnetic tech nique to align im pacted teeth . Presen ted at the 87th Annua l Session of the American Association of O rthodontis ts, Montreal, 1987 (u npu blished).

Nielsen LI, Pryd so V, Winkler T (1975) Direct bo nd ing on im pacted teeth . Am I Orthod 68: 666-70.

Vard imon AD, Graber TM, Drescher 0 , Bou rau el C (199 1) Rare ea rth magnets and impactio n. Am I Orthod Dell fofae Ort/lop 100: 494-512.

Rygh P (1993) The usc of magn ets in orthod on tic therapy: panel d iscussion . Eur I Orthod 15: 421-4.

Ziegle r TF (1977) A mod ified techniqu e for liga ting im pacted can ines. A lii I Grtnod Dentofac Orthop 72: 665-70.

5 MAXILLARY CENTRAL INCISORS

CO NTENTS • A etio log y • Diagnos is • Treatment timing • Attitude s to treatment • Treatment o f i mpac ted centr al inci so rs • Prog no s is • Acut e t raumat ic intrus ion

AETIOLOGY AI the age o f abou t 6 yea rs, in most ch ild ren, a sudden and d ram atic cha ngeover occu rs in the anterior part of the dent ition, with the shedding of the deciduous inciso r teeth an d the appearance o f the pe rmane nt incisor teet h. The first perman ent teeth to eru pt in the yo ung ch ild arc usually the mandibular central incisor s, although the firs t permanent mo la rs ma y sometimes prec ed e them . Th e mand ib ular lateral an d the maxillary central inc isors then eru pt at about the same time, at 6.5-7 yea rs . Und er normal circu ms tances, the max illa ry lateral incisors ar c the last of the incisor s to eru pt, completing th e ante rior den titio n with the ir appearance ab ou t a yea r afte r the eru ption of the ad jacent cen tral incisors. The spectre of eru pted lateral incisors, associated with the non-appear an ce of one or both of the central incisors, s hou ld always be deemed abnormal, whet he r or not a d eciduous centra l incisor is still present, and furt her in vestigation should be u nd ertaken to ascer tain the reason for the abe rration . Congenital absen ce of a maxillar y pe rmanent cen tral incisor, given the presence of per-

mane nt latera l inc isors, is excep tionally rare, alth ou gh it ha s been repo rted . In this situ ation, the shape of the single cen tra l inciso r ma kes it im possible to d istinguish whether it belongs to the rig ht or left side. The pa tient's appearance is abnorm al (Figs 5.1a-c) and rather rem iniscent o f a 'd ental cyclops' !

Obstructive causes Supe rnumerary teeth

When an existing perm anent cen tra l incisor doe s not erupt and the diagnosis of impa ction is m ad e, the most com mon ncnologlc factor is the p resen ce of one or more mid line su pernumerary teet h (Ho ward, 1967; Brin et al. 1982; Z ilber man e t al, 1992) (sec Fig. 1.10 . In a study of a sample of schoolc hildren (Brook, 1974), th e prevalence o f su pernumera ry teeth was found to be between 1.5% and 3.5%. It has also been shown in a d ifferent sample group (Tay et al, 1984) that be tween 28% an d 60% of cases wit h sup ern u mera ry teet h will have result an t eruption d isturbances of the ad jacen t tee th. By arbitra rily integrating these two st udies, it would seem tha t bet ween

54

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

(b'

Ia

Figu re 5.1

(a) Abnorma l lip mo rpholog y, absence of ph iltrum and midline pos ition of sing!.' central incisor , (b) Intra -oral view of same patient to show 'square anato my of incisor and ind eter mina te righ t/l eft designation. The latera! incisors .1 Te late rally fla red as part of an otherwise norma l 'ugly duckling' stage of development. (c) A vj ew of the palate to show bilatera! submu cous clefting. (Courtesy of Dr 5 Ceron.) ( e)

0.42% an d 2.1% of child ren su ffer fro m im pacted cen tral incisor teeth from thi s cau se. Odontome

Among the other an d rar er causes of obs truction thai may eq uall y p reven t the eruption of a normal cen tral incisor is an odontome. These arc vcry variable in size an d type. bu t, w hether the y are of the co mplex or co mposite type, they usually have a broader a nd wi der cross-section, an d their presence will be more likely to prevent er uption of an incisor than wi ll a su pern u mera ry tooth ,

Ectopic position of the tooth bud

The develop ment of a toot h bud in an abnormal p ositi on or in an a bno rmal angula tion may have no apparen t ca use, and may thus be attribu ted to tr au matic or genetic factors (Fig . 5.2). As the result of the d isp lacement, normally placed adj acent tee th may provide a p hysical obstacle to the normal eruption of suc h a too th. Alternatively, other p hysical obs tacles, suc h as the above-mentioned supern umerary teeth or odontomcs, may be the reason . While the early removal of an obvious eetiologlc factor ma y be s trongly

55

MA XILLARY CENTRAL INCISO RS

resorp tion of the d eciduou s tooth will occu r. In these circums tanc es, eruptive movements are minimal, and th e pe rma ne nt too th remains in a more or less uncha nged position over a long peri od . Fina lly, when po sitive in tervention is undertaken, removal o f the cau se will need to be su pplemen ted with active app liance therapy fo r its resol ution.

Traumatic causes Fjgu re 5.2 All ab normally sited cen tra l illci.<;or, whose roo l a pe x is dose to the ca nm.. area. Th.. sha pe of the rool also appears 10 be abnorm al.

ind icated , th is will not necessarily affect the position o f the too th bud, which will probably con tinue to d evelop in its existing loca tion . Variation in the position o f a developing too th w ill produce a co ncom ita nt va riation in its eru p tion path . When the eruption pa th is very slightly defl ected , the too th will usually eru pt, bu t with an abnormal angulation of its long axis, m irro ring the path that it will have travelled . As its vertica l development p roceeds, its relationship to the decid uous predecessor is more lateral, medi al, ling ual or labial. This will bri ng about a partial and ob lique resorption along one sid e of the roo t of the d eciduous incisor. In d ue time , the further progr ess of the perman ent incisor brings it into contact with the CTOwn on th at side of the decid uo us too th. The permanent toot h sometimes remains impacted , if insu fficient space exists. Alternativel y, the tooth ma y finally eru pt ad jacent to the over-retain ed decid uou s too th, possibly in to a crossbt te relationship, or it may be prodined labially, or a dia stema may be produced in the m idli ne. This situ ation may not be self-correc ting, afte r the belated shedd ing or extraction of the s tu bborn decid uou s too th. Shou ld the po sition o f the d eveloping too th be mor e marked ly d is placed , w hich is un usu al, its potential eru ption pa th will be in a more ob tu se d irection, a nd litt le or no

Obstr uction due to soft tissue repa ir

The trau matic, sudden and very early los s of the d eciduous incisor teeth is mos t often the result of an accide nt th at d elivered a blow to d islod ge the tooth, us ua lly whil e the child was at p lay. The possibilit y also exists for thi s to have been cau sed by a d ental ext raction, p rompted by th e presence of d eep caries or follow ing the seq uel ae of an ea rlie r traum a. This typically happens at 3 or 4 years of age, at a time when the permanent inciso rs are not read y to erup t and ,1 healing-over of the macerated gingival tissue occu rred, withou t th e early eruption of the tee th. In time, changes take place in the connective tissue overlying the too th germ , wh ich prevents them from pe netrating the m ucosa (Dibiase, 1971; And reasen an d And reasen, 1994). By the age of 7 or 8 yea rs, one ma y see an d be ab le to p alpa te the bu lging profile of the central incisors (See Fig. 3.2.1). Dilaceration

In the early stag es of their d eve lopment, hig h in the max illa, th e perm an ent central incisor s ar e situa ted lingua l and su pe rior to the apices of the de cidu ou s incisors. As d evelopment p roceed s. their position changes. wi th labia l and inferior migration . As this occur s, an oblique reso rpt ion of th e roo ts of their deciduous prt>dL'CL'SSI)fS is initiated. During th is critical period , it frequent ly happens th at the child beco mes involved in a traumatic ep isod e, in which ,1 blow is inflicted on the d ecid uous max illary incisors, from the front, in a superior and pos terior d irection . If

THE::..::...-----'=-----'-----'::..::...::..::...::..::...-----'== ORTHODONTIC TREATMENT OF IMPACTED = TEETH -"

56

Figure 5.3 Thl' tangential view shows S<.'WIV labia l dbpla(t'ment of the ro...t of the deciduous incisor. (C"urll'Sy of Pro fesso r

J lU~Im.,n n.)

these teet h are displaced superiorly (intruded), it follows tha t a fracture of the alveol ar process has occurred and that ei the r the teeth alone, or together wi th a part of the labi a l plate of bo ne, have altered their pos ition. By and large, thi s displacement 'will cause a la bial fracture of the bu ccal plate, an d the re will be an anterior displa cem en t of the roots

of the already superiorly and slightly palatally d isplaced teeth (Fig. 5.3). Th is u sually ha s little effect on the unc rup«..'d permanent incisors. O ccasionally, however, the thrust of the blow is delivered in the direction of th e long axis of the dec iduous teeth, and ma y be transmitted supe riorly to th e developing permancn t tooth . The resorbing roo t apex momenta rily establishes a po int of impact with the incisal ed ge of the crow n of the pe rma ncn t incisor. This w ill cause the crow n of this unerupted pe rma nent inciso r tooth to rotate u pwards, in its crypt. Since its root is only partia lly developed at this time, th e formed part of the roo t will rota te w ith the crown. However, any fu rthe r root d evelop-

ment tha t occu rs in the post-trauma pe riod will often con tin ue in the sa me d irection as before, p rod u cing a bizarre ang le be tween the pre-trau ma and post-trauma po rtions of the too th . Thi s will produce the typical dil aoerated central incisor, with labial d isplacement. The site of this junctio n will depend upon th e stage of develop men t of the root at the time o f trauma, as w ill the prognos is of any p roPOSI..>d orthod ontic treatment for the too th. Pa lat al, rather tha n lab ial, displa ceme nt of the crow n vis-a -vis the post -traumatic roo t por tion ma y occur in rare ins ta nces, as a va riation of the above theme, a nd is due to a more palatal position of the tip of the developi ng permanen t incisor rel ative to the ap ex of the de ciduous incisor roo t at impact. This is a more likely variation in the wry yo ung, durin g the early calcification of the tooth crow n w he n its palatal location is more p ronounced . This scenario for the causa tio n of d ilaceration is ex tremely well know n, and p roba bly rep resents a majority opi nion w ithin the p rofessio n. Ho wever, w hile this is not ruled out by other aut horities, othe r aetiol ogic possibilities do exist. A developmen tal origin has been suggested as an alte rnati ve (Howe, 1971), with the co nten tion that the acti ve process o f the developmen t of cysts, odontomes or su pe rnumerary teeth may p rod uce this p he nom enon by d isp lacem ent o f the crown of the too th or by in terferen ce and redirection of its roo t. No history of tra um a could be elici ted in 70% of anothe r sa mple (Stewart, 1978) no r could macroscopic or mic ros op ic eviden ce of tr auma, nor the existen ce of a cyst, odontomc or ext ra too th. No CtlSC wa s foun d with both central incisors involved, no r was th ere damage to neighbouring teeth, w hich cou ld be expe cted to occu r in at lea st a few instances if trauma were th e cause. These cases a lso failed to s how tw o d istinct an d an gulatcd portio ns to the roo t, but rather a conti nuous an d tigh t CUr ve (Fig. 5.4), qu ite d ifferent fro m those in w ho m trauma, as an aeti ologlc fac tor, was ev ident. The conclusi on of the lat ter report was tha t a fai rly high proportion of d ilaccrations occu r as a resu lt of an ectopi c siting of the too th

57

MAX ILLARY CE NTRAL INCI SQRS

Figure 5A

An ..xtracted dilaceratcd

incisor.

germ, whos e root dev elop ment is d eformed by its proxim ity to and the ana tom y of the pala tal va u lt in the immediate vicinity. These explanations are unsa tisfactory on several counts. Differen t cases sho w an almos t id en tical and very typ ical an atomy of the tooth, which affec ts maxilla ry central inciso rs exclusively, an d virtua lly nev er occurs bila terally. The cro wn is norma lly shaped . and the coronal portion o f the roo t shows initial norma l developmen t. The a pical por tion , however, d evelops along a circul a r path, in the labio-lin gual pla ne, rather than two straigh t po rtions of root at an angle to one an ot her. No t only is the anatomy typi cal. but the positio n an d orientation of the too th is also unique. The crown of the too th is di s placed high on the labi al side of the su lcus, witho u t lateral rotation, an d its palatal aspect is palpable close to the roo t of the nose. Often, the roo t apex is palpa ble on the palata l sid e of the alveolus, and may be the sign tha t in fl uen ces an unwary surgeon to mistakenl y ap pr oach exposure of the tooth on the wrong side! And reasen an d Andreasen (1994) have su ggested that the loss of a decid uous incisor may lead to scarring alon g the eruption pa th of the pe rm ane nt incisor , which defl ects the developing too th labially. This ru ns coun ter to Stewa rt's observa tion thai no history of early tra umatic loss of the d ec id uou s too th had occu rred in 709', of the cases. There is an a lternative hypothes is. It is possible to read a comp letely d ifferent neti ologtc interpretation into these constantly occu rri ng

feat u res, an d it is pertinen t to beg in by qu estion ing the reliability of a child's or paren t's mem ory regard ing trau matic in ju ry of the fron t tee th. Seve re trauma is ra re and always remembered, but no n-d isfigu ring trauma (i.c. trau ma that causes ne ither fracture nor di splacem ent to the anterior teeth) occu rs quite frequen tly in yo u ng ch ild ren, is rarely noted an d almos t never remembered in the years that follo w . Abrup t and vertically d irected force throu gh the long ax is of the dec id uou s too th will br ing abou t the transference of the im pact to the inti ma tely related , uneru pted , permanen t central incisor. Becau se the long axis of the perma ne nt inciso r ha s a mor e labially tipped orientation , th e force will be tran sm itted in an oblique line that runs thro ugh the incisal ed ge and a point on the labial sid e of the newly forming roo t, close to or at the root- mineraliza tion interface (Fig. 5.5). Since the blow will be d elivered d irectly to the sensitive cells of Hertwig's root sheath, via the kn ife edge of the incompleted roo t at this in terfac e, conside rable dama ge ma y be inflicted w ith relatively low force values. It will be app rec iated that precision in d irec tion ma y be more critic al than force ma gn itude. It is entirely possible that the roo t sheath ma y only partial ly recove r from the blow , wh ich may resu lt in an attenu ated rate of p roduction of denti ne on the lab ial side of the too th . With the remain d er of the root-forming sys tem con tin uing to produce dentine u nsca thed, und eterred an d u nabat ed . it follows that the final shape of the root of this too th will conform to a con tinu ou s Iabiallv d irec ted curve (Fig. 5.6), u nt il apcx ificat ion is achiev ed . Fu rthermor e, since th e dental pap illa base of Hcn wlg's root sheat h maintains its po sition within the elvcolor p rocess fairly cons tant ly - aga inst th e eruptive force of the d evel oping tooth - an d p rovides the p latform from which the roo t is d irected , the crown o f the incisor moves labially an d s uperio rly for as long as this asymmetrical roo t mineralizat ion co ntinues . In othe r wo rds, d ilaceration of thi s classical type, is
58

_ __

_

_ __ __

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

---'--.::.==~.::.=.::.=_=__.:::_c.c.:.::.:.::::...:.::::C'_'

for the typical appearance of the dilacerated tooth, as well as its fina l unerupted position under th e nose. Furthermore, since it may occu r with a relatively minor degree of trauma, thi s could account for the high proportion of cases with no appa rent trau ma experience . Its rela tive rarity may be due to a hig hly cri tical and specific positional relationship betw een the d eciduous and perman en t incisors, at the time of in ju ry . This may accoun t for an absence of bilaterally affected cases , for its non-occu rrence among lateral incisors an d for an absence of any association with supemumer.1 ry teeth, cyst s an d odontomes . Arrested root developme nt Fig u re 5.5

A diagram to shew ho w a \'crtica lly direct..od force through the decid uous indsor is tr..m ~m itl ....t to the la bi,l l aspect of th e mineralizing roo t of the unerupted pcrmalien! incisor.

He rtwig's root ' -e,ath

When a presc hoo l chil d su ffers a very severe blow to the maxillary anterior dentition, this is likely to res u lt in the loss of the decid uou s incisors, and may cause fractu re of one or both jaws. The d amage to the roo t-prod ucing ring of cells that for ms Hert wtg's shea th may have been so ser ious as to ha ve effective ly cau sed the cessation of an y fur ther root d evel opment. These teeth may lose th eir erup tion po tential, w hile the ad jacen t teet h will continue to eru pt. bringing wit h them vertical proliferation of alveolar bo ne . Only at a much later stag e will thi s phenomenon be discovered, when th e affected tooth or teeth do not erupt an d an area of vertically deficient and bucco-palatally na rrow, edentulous , alveo lar rid ge is ev ident. Rad iog raphs w ill us ually reveal the crown of the too th to have a normal axial inclination , but the too th will be sit ua ted ve ry high up in the premaxilla, with minimal or no root formation, d ep en ding on how much roo t had already developed at the time of the accid en t. Acute traumatic intrusion (intrusive luxation)

Figure 5.6 A d iagramma tic ilIu..tra no n of th e• p rog fl;>';..ive a Iteration in th.., position uf .1 dilacera ted incisor, d Uring uncquill root f\,rm,l li"". ;'\;01,' that the pos itio n of Hertwlgs rool ..h..-ath remains u naltered .

Tra umatic in jury occurs in yo u ng children as the result of play-related acti vities in schoo l and at ho me . in accidents involving a fall or, occasiona lly, as the res u lt of deliberate p hysical vio lence (Andreasen and And reasen, 1994). Effects on the teeth range fro m a transitory pu lp in flamma tion, through the various

MAXILLARY CENTRA L INC ISORS

types of fractu re of the crow n of th e tooth and o f its roo t, a nd, in the seve rest cases. avulsion o f the e ntire too th , Intr usion of one or more of the incisor teeth is ofte n associa ted wi th a fra cture or com m inu tion of the lab ial plate of bone a nd a tea ring of the pe riodontal fibres. A child may prese nt a t the e mergen cy clinic wi th wh a t gives the a ppearance of a total avulsio n, s ince the too th is not vis ible in its for mer p lace, the gingiva is lace ra ted an d ther e is a co nsiderable amount of blood dot. A pe r iapical radi ogra ph of the a rea w ill re veal a superior displacement of the too th, int o the alveola r bo ne, without necessa rily producing a fracture of either the crown or th e roo t. The labial plate is d isplaced labially, although it is most often held close by the injured but uninterrupted band of labial gingiva an d soft tissu e. The integrity of the blood supply 10 the soft tissues is usually intact, and this all ows good and rapid soft tissu e he aling . In a sense, thi s tooth has been tot allv avulsed, bu t inan atypical ma nne r. It is cornpletely d isplaced fro m its socke t, with a total severa nce of its attach me nt a pparatus and a d isrup tion of its vita l supp ly lines. Whe n compared w ith the typ ical av u lsed case, howeve r, it has enormou s ad va ntages : the too th has not been all owed to d ry, it has not been in contact w ith any form o f conta m ina ted ma te rial, an d it is not nec es sa ry to store it in saliva or mil k or other recom mend ed iso tonic medium be fore restoring it to its forme r place. It is situa ted in a n area initially su rround ed by a coagu lating haematoma an d lat er by a n organizing blood clot, and it m ust be as sumed tha t the damaged period ontal fibres in this situa tion fare conside ra bly bette r than do th ose of the repla nted tooth, w hich has sp ent some time ou t of the m ou th .

pro vid ed . Accord in gly, such aspects as pre vious illne sses, pa r ticularly rhe uma tic heart d isease, drugs be in g presently ta ken a nd bleed ing tend encies, toget he r w ith an y o the r im porta n t a nd releva nt item s o f information, m ust be elicited a t the outset. Question s should be asked w ith particu lar e m phasis p laced on the possibili ty of an e pisode of tra u ma . The pa ren t should be ques tion ed carefu lly to d iscover whether the chil d is accident-prone, in ge ne ral. Direct mention o f bicycle accidents, falling from a chair, a ladder or a tree , or being hi t in the mouth during pla y should be made, and a ll relevant answers should be ca refu lly recorded, together w ith the approximate dates of their occurrence.

Clinical examination Mu ch of the d en tal history is possible to ascerta in from a gla nce a t the d entition itself . Th e existence of sealants an d res toratio ns, the absence of teeth, gingiva l int1a m mation a nd the leve l of oral hygie ne w ill of ten tell a great d eal a bo ut past a ttitudes o f both the pati en t an d the a ttendi ng d e nt is t to preve nti on a nd to th er a pe utic proced u res . The prese nce or absence of the d ecid uous inciso r is ge ne rall y irrelevant. The cent ra l incisor of the op po site side an d the lateral incisor of th e sa me sid e wil l us ually be seen to be tipped towar d s a ile an other, an d there will usua lly be insu fficient space at the occlu sal level for the placeme nt of the u nerup ted tooth . Widely d ivergent roots of the two ad jacent tee th will su ggest the presence of an unseen a nd u ndiagnosed

physi cal obstruction .

DIAG NOSIS

Palpa tion

History

In obs tru cted cases, the u ne rup ted too th itself is often hig h on the labial side of the alveola r ri dge, an d ther e may be ad d itional an d smaller irr eg ularities bu lgi ng the a lveol us more in ferio rly, w hich Me bes t id ent ified by pa lpation. Th e re w ill al most always be a

The pa tie nt' s med ica l his tory should be record ed carefu lly. It m us t be borne in m ind that s urgical interven tion is very likely to be an essen tial pa rt of the treat me nt that is to be

60

THE O RTHODO NTIC TREATMENT OF IMPAC TED TEETH

labio -lin gua l wid eni ng of the ridge. If the rid ge Mea is relat ively thin in feriorly, this will ind ica te tha t teeth a re no t p rese nt a t thi s level. TIle importance o f pa lpa tion of the area is not to be underes tim a ted , since, if it is no t performed with sufficie nt thoroughness, an importan t diagnosis may be missed . The p resence of a d ilacerated centra l inciso r w ill only be revealed by clinical examination if palpation is mad e " cry high in the labial sulcus . Normally. the superio r mid line area is delincated by the pro mine nce o f the anterior nasal s pine, on each side of which a s hallow d ep ression w ill be felt. The palatal surface of ,1 dileccra tcd incisor crown faces forw ards and p roduces a hard swe lling in the place where the sha llow d epression is expected . By su periorly ret racting the upper lip, the oral mucosa ma y be seen to mo ve freely ov er the stretc hed area, wh ich w ill emphasize the outline of the cing u lum o f th e too th. Palpa tion of a dilaccrn tcd central incisor ma v often be ma d e in two pla ces. With the abno rmal position o f the coronal por tion of the tooth, the further develop ment of the root po rtion may be along an axis that is tipped mo re lingually, an d , in the later stages of roo t closure, the apex may become pa lpable as a small and hard lump in the pa late. This is a fea tu re that few clinicians seem to loo k for, and is more consistent tha n may be realized (Sew a rd. 1968).

Radiographic examination In Chapter 2, the di fferent met hod s of radiographicall y viewing u nerup ted teeth were dis cuss ed in genera l. and it wa s point ed ou t tha t a periapical view p ro vid ed essential qualitative info rma tion and . as such, should be the first step in this part of the examina tion. In the case of an u neru p ted central incisor, this view will ge ne ra lly sho w associated pa thology with grea t clari ty, includ ing har d tissu e obs tru ctions (su pe m u rnera ry teeth of various types and cdcnrornes) , soft tissu e lesions
tooth. Fro m th is alone, it will usually be possible to establis h the reason for the failu re of the too th to eru pt. If supernu merary teeth or odontomes are see n on the film, the information tha t will then be required relates to thei r size, their nu mber and th eir mesio-d istal relationship to the mid line a nd the inciso r tee th, all of w hich will be obvious from this view. However, their labio-lingual orientation in rela tion to the ad jacent eru pted tee th will not be obviou s from this one film . Since the pe riapical view is ob liquel y angled to the horizontal p lan e, a labial s upern umerary too th will appear lower in the vertical plane than a palatal su pern umerary tha t is situated at the sam e height. Accordingly, the ass essment of hei gh t is directly rela ted to the lebio-lt ngual po sit ion of the too th. At the age at which most pat ients will att end for treat ment , a true lateral, tangenti al view is not help ful, due to the superimposition of cen tral and latera l inciso rs, d eciduous canines an d u ne rupted pe rmanent canines and the su pernu merary teeth . A second pe rtapical view, d irected from a more d istal vantage point, w ill us ually help to localiz e the relative position of th e unerupted teet h, using the p rinciples of parallax . Similarly, a rou tine (oblique) occlusal film, w hich we earlier described as a more stee ply angled pe riapical view, will help to separate out the images of the unerupted teeth, u sing the same pa ralla x pri nciples, this time in the vertica l plan e. This will then p rovide the information needed to compu te the relati ve heights of the indi vid ual s truct u res . A good vertex occlusal film, di rected through the long axes of th e anter ior teet h, will provide une quivocal ev idence of labio lingu al too th position, particul arl y if th ere is m arked d isp laceme n t. Dilnccrntcd central incisor teeth \v ith labial d isp lacem en t have a ve ry special and characterist ic appearance on a periapical radi ograph. We ha ve already d escri bed that the crown and th e de veloped part of the roo t were rotated lab iall y and superiorly at the time of the trau ma or p ursuant to it. The long axis of this pout of the too th lies in the di rect line of the X-ray beam, which is d irected at ,1 periapical

MAX! LLARY CENTRAL INCISORS

film of the a rea, and accordingly will show up as a cross-sectiona l view of the crown, superimposed upon a cross-sectiona l view of the widest part of the root. Th e a pical (posttrauma ) po rt ion of the root, on the other ha nd , continues to grow roughly along its original course. It will the refore be read ily u nd ers tood that the la bial su rface will be seen to face superiorly a nd the cing ul u m dearly outli ned. in fe riorly. Th e roo t apex will be see n as a ve ry short 'tail' extending superio rly a bove the tooth's labial sur face. The p icture is reminisce nt of a scorp ion, viewed from the fron t. Although this is clearly recogniza ble, the film g ives only a n indica tion of its height in the alveolus, wh ile its gen er al apico-lncisal ori entation ca nnot be defined . Co nfirmation of the d iagnosis may then be positively made, usin g a ta ngential or lateral sku ll radiograph. Th is w ill gi ve informa tion that will hel p to build up a more compre he nsive p icture of the too th, particu larly regarding det ails o f its morph ology, its heigh t an d its overall longaxis o rienta tion.

TREATMENT TIMING In C hapter 1, we discussed the occu rre nce o f a cha nce pa thological finding during routine X-ray examina tion. Obstructio ns should be removed w he rever possib le before they ha ve the cha nce to create a situation o f dela yed eruption, in order to obviat e the need for or thodontic treatment. There is, howe ver, no preventive tre atment to be reco m mend ed once tra u ma has generated the dila cer at ion, and the pa tient will need to wait for the time when corrective treatmen t is ap pro pria te. Wh en a patient presents w ith a sin gle central incisor an d both la ter al inciso rs eru pt ed, the no rmal eruption date of the second ce ntral inciso r w ill have passed . The impacted too th w ill be see n on the periapica l radi ograph to have at least tw o- third s o f its roo t, the d e velopm ental la nd ma rk tha t determines tha t a too th shou ld be eru pted. Orthodontic and su rgical tr eatmen t are therefore indicated at that time, both for obstructive impactions a nd for the d tlacerated tooth.

O ften, at this early sta ge, on e may be able to foresee a n obvious need for orthodont ic trea tment for other reasons - treatment that may not normally be advised until 3 or of years lat er. It is not reasonable to delay the resolution of an impacted central incisor for this period of time merely in the interests of trying to achie ve a single- phase orthodontic tr ea tment plan in the full pe rmane nt dcntition .- Th e alig nme nt of the impacted tooth should be unde rtaken a nd e xecu ted efficien tly, av oidi ng u nnecessa ry a tte nti on to othe r d e tails. Root uprighting a nd torqueing should be pe rformed as indicated , but an ideal final an d artis tic alignment is not the aim at this s tage. Once ap pli a nces a re removed , following the restora tion of normality, there will be natural sponta neo us changes in th e alignment of the se tee th during the man y mo nths that follow an d before the perma ne nt ca nin es come in to their place. It must be po inted nut to the parent that th is is expected to happen, and tha t it is normal an d not a subject for co ncern . Th e pare nt a nd pa tie nt should be ad vised that further trea tmen t will be necessary a t a lat er d ate, for the remainder of the overall malocelusion. and that retention of the aligned incisors agains t these physiologica l movements is no t advised .

ATTITU DES TO TREATMENT There has been a more or less sta nda rd p ro tocol of trea tmen t available for se vera l decades in the orthod ontic p ro fess ion in Europe regarding normally developing bu t impacted central incisor teeth. The recommendations ad vise (a) that ad equa te space be prepared for the too th in the arch, and (b) that the ca use of the non-eruption (us u ally a supern ume ra ry too th ) be elimina ted . The im pacted centr al incisor teeth should then usually erup t spontaneously (Ba ttagcl. 1985; H ou ston a nd Tulley, 1986; Mills , 1987; Mitchell and Bennett, 1992). In the absence of

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

~:..:::======.:..=...:::::_==_=:::

62

adequa te sp.le e, it has bee n reported that eruption rarely occurs (Dibiase, 1971). St udies that ha ve be en made of pa tie nts who ha ve u nd ergone this type of trea tment have s hown d isa ppointing results with reg a rd to th ree im porta nt para me ters.

2

3

Non-eruption, Sp ontaneous eru ption has been va r iously re ported as occu rr ing in 54-78% of cases (DiBiase, 1971; witsenberg a nd Boe rtng, ]981; Mitchell and Bennett. 1992), w hich re presents a low degree o f re liability of the method. Dday in eruption. Even w hen eruption occurs, the average tim e for the affected too th to ma ke its appearance in the mouth is be tween 16 a nd 20 months (Boden harn, 1%7; DiBiase, 1971; Mitchell an d Benne tt, 1992). Th is is a n unacceptably long period of lime when on e considers that th e pa tie nt w ill be wi thou t a fro nt tooth or tee th fur so many months. Ad d itiona lly , 25% of the patients needed to ha ve tw o su rgical ep isodes, followed by a wa iting period of 2.5--3 yea rs before the tooth erupted (Mit chell a nd Bennett, 1992)! In .1 retrospe ctive s tudy of cases in w h ich (.1) s pace ha d bee n p rovided, (b) the su pe rn u mera ry tooth had been rem oved a nd (c) a stainless s teel crown ha d been ceme nted to the impacted too th, eru ption w as found to ha ve occurred in 96% of the pa tients. H owe ver, this required a n evorcgc time span of 3 years (M un ns, 1981)! Aligl1l11t'1I1. The third pa rameter th at showed di sappointing resu lts relat es to the ade quacy of spontaneous alig nment. O f the inciso r teet h tha t did erup t (64%) in the s tudy of Mitchell and Bennett (1992), 59% we re found to align themsel ves reasonably we ll wi thout the use of a p pli an ces an d 41% req u ired the use of orthodontic appliances to achieve the reso lut ion o f rot a tions and root d isplacement. According to Gard iner (1960, however, spontaneous alig nment occurs on ly in a minority o f pa tients. Clearl y the cr iter ia fur d ecid ing w ha t cons titu tes a n acceptable 'alignmen t' va ries from one clinician to a no ther an d, on e may be pe r-

mined to specu la te, upon w hether the trea tme nt is being carried ou t in a commu nity health clinic or in a pr iva te orth odontic practice . Some worke rs (Day, 1964; Kettle, 1958; Hotz, 1961) recogn ized the need for a ffirm ative action to control (i.e. activel y encourag e) incisor e ru pti on, and de vised me thods to perform this, us ing w ire loops a nd p inning, a nd e ven ad vocated the passing of a w ire th ro ugh a drilled hole in the incisal edge in those early days. Mills (1987 ) warned aga ins t the ex posure of the crown of the perma ne nt tooth during the procedu re to remove the supern umerary too th, warning that pe riodontal progn osis of the final result would be compromi sed . Beyond the use of a sim ple remova ble ap pliance to make space in th e arc h fOT the unerupted incisor, he displa yed a ret icen ce to u se mec hanothe rapy, an d seemed to ha ve infl uenced opinion in Britai n, w he re there a ppea rs to be a w ide consensus that the uSC' of a pp liances in bri nging d own im p acted central inciso rs is something to be avoid ed. H is reasons for thi s a ttitude a re as follows: (a) th ese tee th of te n e ru pt s po ntaneo us ly, w itho u t help; (b) loss of labi al bony pla te; (c) poor g ingival ma rgin, w ith less att ached ging iva; (d) gingiva l level d iscre pa ncy . Little ob ject ive research is offered in su ppo rt of these contentions, a nd it is equally open to speculation that most or all of these factors could be adver se ly af fected by overenthusiastic or ot herwise p OOT su rgical tech niqu e (Becke r c t ill, 1983; Koh a vi et al, 1984). This issue is d iscu ssed fu lly in Cha p ters 3 and 6. A mi nority of child ren w ith most other ma locclusions a rc rarely brought to the orthodontist mu ch be for e 10 or 11 years of age, yet the ma rred appea ran ce of the child w ith a singl e erupted centra l inci sor generally encourages the parent to see k trea tmen t m uch earlier. An orthod on tist' s lac k of concern for a ra pid sol u tion, in respunse to the parent's d isquiet for the ch ild's comp romised a p pea r-

MA XILLARY CENTRAL INC ISO RS

ance, is insensitiv e, if not callous. This is par ticu larly d isturbing in the p resent context, since simple and effectiv e means of achieving th is end are freely ava ilable.

TR EATMENT Following a determ ination of the overall orthod ontic d iagnos is, a p roblem list sho uld be d rawn up. Occasio nally, there ma y be just one item on the list, namely the impacted toa th. More often, the presence of mandi bul ar inciso r crowd ing, pos terior crossbite or a class 2 relationship may also be noted, and the clinician mu st th en d ecide which of these is to be treated in this ea rly treat ment phase and which is left un til later. As a general ru le, treatment priority should be given to the unerup ted incisor, and all other or thodontic procedures d elayed u ntil the inciso r has bee n brought in to alignment. However, an an terior or posterior crossb ite and malalignment o f the eru p ted incisors will usually be treated at the sa me time as spa ce is being p rovided for the im pacted incisor tooth.

An orthodontic appliance for use in the early mixed dentition As has bee n po int ed out, opening the space for the un erupted tooth prior to removal of the supern ume rary req uires some form of ort hodont ic ap pliance. Th e simple removable p late is manifestly unsuitable, since the only pos itive influence it is capable of producing is a lateral tipp ing of the ad jacent teeth. While this creates spa ce in the arch, it does so on ly at the corona l level. The effect is quit e the op posite more apically. where the roo ts of the tipped teeth will be moved toward s one another and di rectly into the path of the (it is to be hoped) erupting im pacted tooth. Vertical force control on the im pacted tooth is d ifficult to achieve w ith a removable appliance. Corrective rotatory move ment of the finally erupted too th is rarely ad equa te, while u prighting and torq ueing root movemen ts

are qu ite im po ssible. A practitioner using this method would essentiall y be p laced in the seat of an observer, being able to exercise virtu ally no control over er u ption, w hich is the mos t im portant aim o f the exercise. It is true that in the eve nt that the too th eru pts (a) spo ntaneo usly and (b) into good alignment there has bee n mu ch to gain by this relative inactivity, apa rt from the u nreason able dema nd on patience that is mad e of the child , w ho may be without a front toath for a very long time. An impacted tooth init ially shares the limited labio-Iingu al wid th of the alveolar ridge with the supernumerary tooth, wh ich preven ts its eruption . Sharing thi s space usually causes the roo t of the cent ral inciso r to become d isplaced in either or both the labiolingual and mesio-d istal planes of space. It is th erefore likely th at, in the final analysis, the eru pting tooth will require root movement in a labio-li ngual (torqu eing) and /or in a mesiodi stal (uprighting) direction , and this may be accompanied by the need for significan t ro tational movement. It becomes evid ent that a com pletely d ifferen t type of ap pliance is ind icated - one that has the potential to d eal efficiently with all these even tualities. Given the significantly high num ber of cases ".'here er u ption has prO"d uced an unsa tisfactory alignment o r where eruption has failed completely, it is essential to seek an alternative method of mechanotherapy th at provid es sim ple and rapid so lutions to all the mo vements req uired . A technique mu st be employed th at p rovides sa tisfactory an swer s to the following fou r as pect s: 1

2

The ap pliance should have the capacity to level and rot ate th e adja cen t teeth rapid ly and, with cont rolled cro wn and roo t movemen ts, to open adequate space to accomodate the impacted tooth. This space is demand ed bot h
- -.: .::.::======-=-====

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

64

3

-I

good periodontal prog nos is, as descr ibed in Cha pte r 3. The a ppliance m ust hold the spa ce during an d after the surgical proced ure. Light an d co ntrolled ex trusive forces must be genera ted fro m the applia nce to work over ,1 long ra ng e of movement, to bring the too th dow n to the occlusallevel. Final detailing of the position of the impacted too th a nd its erup ted neighbo urs m ust be com p leted withou t cha ng ing to a nothe r a ppliance. indudin g movement of the crowns a nd roo ts of eac h o f these tee th in all three p la nes of space.

While it is important that the a p pli a nce ha s this facilitv, we ha ve refe rred to cases w here, a t an ea rl}' sta ge of dental de velopment, it is not wist.' to achieve the ' final' alignment of the ideal adult dentition. Thi s is pa rticula rly so when the permanent ca nines a re very high a nd in close rela tion w ith the ap ical third of the lateral incisor roo ts. Ty pically , ou r young affected pa tie nt has tw o molars an d no more than three incisor tee th of the e ru p ted ma xilla ry perma ne nt de ntiti on. The decid uous ca nines a nd molars ha ve insu fficient crow n heig ht a nd un fa vourable a na to m y to all ow the place me nt of a fixed m ul tibrnckc tcd a pplia nce. Fur thermore, ther e is ra rely an y need or inte ntion to move them . Accord ingly, mo s t practit ioners sideste p them an d ba nd only the molars, w ith bon ded brac kets on the in cisors, leaving a lo ng spa n of unsu pported w ire in the buccal region - the 'tw o-by-four' a ppliance. In the ea rly inciso r-ali gni ng sta ges, the ar ch w irc mu s t be of fine gauge. Distor tion is di fficult to avo id , a nd cons equen tly the aligning activit y of till' w ire is nu llifie d . Because of the long Sp<1I1, ther e call be litt le effec tive ver tically ex tru sive force d irected fro m th e mo la r tubes, ev en w hen the a rchwi re ga uge is subs ten tiall y in crea sed . An chorage for the extrusive movement of the im pacted too th is the refore poorly e xplo ited, a nd is lim ited to the ad jacen t incisors, w hich progressively intrud e as the trea tme nt p roceeds.

Johnson's (modified) twin-wire arch An upd a ted ve rs ion of the obs ole te a nd large-

ly forgotten Johnson twi n-w ire applia nce (Johnso n, 1934; Shepard, 1961) p resen ts certain unique feat ures tha t ma ke it especia lly suitable a nd efficient in the ma ny trea tme nt aspects of this speci fic p ro blem, pa rticula rly regard ing anchorage in the vertical pla ne. Th e a pplia nce is ba sed on fixed molar ba nd s, intercon nected by a soldered palatal a rch (Fig. 5.7). Lo ng narrow-ga uge (0.020"

,.)

'b} Figure 5.7 An ' .... dU~1 1 vi,'w of [ohnson's (mod itit'd ) tw in-w ire a rch , to sho w t he sn kh'rt'd p' 11<11,11 arcb. (b) 0 ,020" round tube s\"C tinns ,HC slotted in to the {).[}3(," round m olar

(
tubes. The an terior sectiona l archwire in this case is a single 0.016·' w ire. si nce on ly o n",erupted permanen t incisor is presen t and the usual multistranded wire is not need ed . The alignment of the buccal tubt's shows ,1 do w nward tip as they proceed ml'Si
65

MAXILLARY CENTRAL INCISORS

in ternal d iameter) tubes slid e freely in the round molar bucca l tubes (0.036"), and are made to exte nd a nte riorl v to the deciduous ca nine area. An initi al a~lterior m ultis tra nd sec tional wi re (0.0175") is held into the long na rrow tubes by a friction fit, crea ted by placing three or four be nds in the multistran dcd wire an d then d rawing it through the tu be between two grooved pliers. Whe n the appliance wa s in gene ra l use, several d ecades ago , an d in comp liance w ith its na me, two fine 0.010" stainless steel w ires we re used in the an te rio r portion, to provide im proved flexib ility an d springiness, w hic h todey's m ultist ra nd wi res achieve to a considera bly hig her degree. The first step in the construction of the a ppliance requires that a n impression of the d enta l a rch of the pa tient is tak en, wi th p roperly ada pted plain molar ba nds in place. Th e ba nds a re re moved carefully fro m the teeth and reset into the impression be fore pou ring . O n the mod el, a pala ta l a rch is fab rica ted and soldered to the lingu al side of the molar ban d s, to provide resista nce 10 the ext rusive forces tha t will be need ed la ter. Buccal tubes a re be st soldered to ensure precise alignm en t w ith the an te rior bra cke t position. Slight upward or d ownward tip pin g of the molar tubes, to su it the needs o f an ind ividual case (Fig. 5.7b), w ill create a s ignificant intru sive or extru sive ver tical force co m po nent on the a nteri or teeth . The labial archwi re is constructed on the mod el, in itiall y u sing a m ultistrand wi re in the bu ccal tubes. The appliance is tran sferred to the mouth and cemented in pla ce, brackets are bo nded to the a nterior tee th, an d the prepared initi al nrchwtrc is pla ced . The bracke ts ma y be of vir tua lly any type, al th oug h th ere are seve ral inherent ad vantages to Bcgg bra ckets in this situa tion. Th eir ve rtical slot makes the m pa rtlcularly suited to the light vertical traction that may need to be a pplied to encou rage the eruption of the im pacted tooth . By the secon d or th ird visi t, some weeks la ter, alignm ent of the three eru pted inciso r tee th w ill u su ally ha ve bee n achieved, and the m ulfi strand ed w ire is d iscarded . It is replaced by a plain round s tainless steel 0.016" (for Begg) or O.Ol S" (for Ed gewise )

wire, which is similarly inse rted in the long na rrow -ga uge bucca l tubes. An e xp anded coil sp ring is th read ed on it and tied into the anterior po rtion, com p ressed be twee n the tee th on eithe r sid e of the impacted too th . Space is gained very ra pid ly. If edgewise bracket s a re USl'CI, the mo ve men t w ill be at least p artly by tipping, an d subsequent uprighti ng w ill need to be pe rform ed w ith a heavier ga uge w ire o r using a uxill iary s pri ngs. Once there is adequate room for the unerup ted tooth an d uprig hti ng has been achieved, a piece o f s ta inles s s teel tu bing should be th read ed onto the e rchwirc. the length of the lu be being cut so that it fits e xactly be tw een the bracke ts of the teeth adjacent to the im pacted too th . The presence of the tu bin g between the adjacent teeth ensures maintenance of the req u ired spa ce an d contributes to the rigi d ity o f the a rchw ire. Th is in tu m provid es a finn pla tfonn fro m w hich light force may be appli ed to the unerupted too th. At this poin t, the pa tie nt is read y for the surgical episod e, in w hich the retained deciduou s incisor an d bu ried su pe rn umerary too th are re mo ved. The pe rma ne nt incisor is exposed an d a n at tac hment placed . All this is ach ieved w itho ut removi ng any part of the orthodontic a pplia nce. If th e pa tie nt is seen eve ry 14-21 da ys for ad justment, a p reviously ob struct ed tooth w ill usu ally eru pt ve ry rapidly, an d wi thin weeks it will be visible, to provid e the young patient with a mort' acceptable appearance, w hich will enhance his or her self-confide nce a nd se lf-image. The favourable time facto r is a n advantage that shou ld not be u ndcrcstim ated. a nd one tha i nee d s to be ta ken in to accou nt , even w he n trea ting the younger pa tien t. A dllaccrntcd incisor w ill tak e longe r to resol ve, but the treatment p rinciples are the same (Figs 5.8 a nd. 5.9). A t the point wh en th e tooth reache s the occlu sal level , a reass essment is ma d e CiS to wh ether uprigbttng. torq ueing or ro ta tion of the too th is need ed . If so, the eyele t is removed and a brac ket simila r to that on the othe r tee th is placed in its id eal po sitio n. Fin ishing is then achieved in the a ppropria te ma nner (Fig. 5.10).

66

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

Figure 5.8 A diff<;>/Vnl patien t is shown here 10 illu strate SUrgical e xposu re a nd attachment bonding afte r adequate space has bee n reopened.

,.,

(b'

(d

ou

Fig u re 5.9

(a ) Fu ll ffig.lgemen t o f the wire in the bracket increa ses th.. verticaltraction compo"",,,!. (b) 45 mo nth s f'O"'l ~urgf'T)', following three visit.. lor adjustmt'nt.the Impacted central incisor is p alpa ble mo re' inferiorly. A bracket has been p laced on the newly t>fUptt"d lateral inOs."r . Ccl9 months po,;h u rge ry. th" tou th is Wt ,n O!TUptro an d labially di ..p laced a nd rota ted . (d) 11.5 m,mIQ'i post-surgery• adequate ali~nml'nt hots OC'L'I\achie...-ed.

67

MAXILLARY CENTRAL INC ISORS

,,

C,I

o»

Cd

en

rtac-es.to (a,b) Tangential views of the anterior m,lxill,l uf cnsc iIIu~lrMl'
The orthodontic treatment procedu re is very simple, an d docs not requ ire a high level of expe rti se. The laboratory stage of applia nce cons tru ction requ ires accu rate sold ering of the pal atal arch and careful alignmen t of the

buc cal tubes, which a good orthod ontic techn ician should ma ster very q uickly, although the orthodontis t may p refer to d o this himself or herself. In the mouth, cementation of the bands and bonding of the b rackets is routine,

68

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - -- - - - - - - - -- - - - - - - - - e nd the a pplicati on of the pre pared archwire p resents a neat an d rob ust applia nce in the long spa n be tw een the molar tubes an d the incisor brackets, w hile anteriorly providi ng light and gentle vertically directed forces of good range, to give rapid results. The p resen ce of the palatal arch w ill ensure that undesired movement of the adjacent in ciso rs and the dista nt anchor mo lars ca nnot occu r. In commo n w ith other pa tien ts w ith unerupted incisors, the patien t w ith a rrested root development will usu ally seek ad vice a nd tre a tmen t before the age of 9 ye ars. By

contrast, howe ver, in these cases mo re th an one and oc casio nal ly all the max illary inciso rs may ha ve been similarly affec ted . While the p rinciples of treatment arc the same .1S for the patients we have already d iscussed , it is clea r that, in the most severe of cases . even a p,lTtiall y bra cketed fixed appli a nce m.1Y be ina ppropriate. In o rder to overcome the problem, a hea vy buccal arch wire of 0.036" (0.9 mm) ga uge ma y be fitted into simila r-ga uge round lub es on mo la r bands ca rrying a soldered palatal arch (Fig. 5.11).

,.,

(1))

(J)

Fig ure 5.11 (a) Th is v-yea r-old ch ild hil~ 1".,1 alveola r bo.lllL' height
spine.

'"

(d)

Vicw uf sohh· wd pitl'''il l arch.

(e)

The toosors are surgically

e xposed . 1'01(' th e la rge ,\11' .1., of hypopla..tic e na mel . (f) Eyelet attachments arc bonded. (g) Alit'!" su tu ring..., sclf-..;u pport ing 's topped' labia l arc hwire is

MAXILLARY CENTRAL INCISORS

(h)

(j)

p lan -d in to the mola r tubes. Displ.l «'d s uperiorly by gc nt l.: (inllcr pressure, the anterior part o f the archwire i.. en..nan-d by all fou r steel p igtai ls, to deliver e Xlrusiw fora". Ih, i) Tangential and anterio r occ lusal radiographic views Immediat ely post-surgery. (j) A clinica l v iew at com p lo.,tinn o f trea tmen t. tFigu n' 5.11 colltiPlIltJ)

70

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - - - - - - - - - - - - - - -- - - - - (Figure 5.11 ((Illli/wedl

(k)

m Ik, Il I'ertapical and tangential radiographs at completion uf treatment. :'>:ote poor dl'n·lopmenl...an..tomical form and life expectancy of the teeth at the cnd of tn.'atmcnt. Lprighting of ttl\' mnt.. was considered ina pp ropri ate.

MAXILLARY CENTRAL INCISORS

At the comp letion of thi s phase of treatmen t, and for all of the types of problem described here, it is good p ractice to pe rform ,1 reassessm en t of the overall orthodontic condition . Further trea tment may be advised at this stage, as me ntioned earlier. Mor e frequentl y, however, the applianc e is removed and the pa tien t is placed on recall over a pe riod of several years until the eruption of the full perman ent d ent ition, when a ne w clin ical assesseme n t is made and an overall treatment pl an is developed for the entire dentition .

PROG NOSIS The obstruc ted impaction The prognosis of the resu lt is depe nd ent on several factors. Root length

The root len gt h is almos t always norma l in impacted teeth, although in some cases the roo t may be somewhat shorter, owing to the cramped circu ms tances in whic h the root d eveloped , p rior to treatment. Neve rthel ess, a m ild degree of sh ortening w ill not normally ad versely affect p rognosis.

71

accompanied by a vertical increase in the alveo lar bone associated wi th them . Thus, w he n the impacti on of a too th is resolved by augmenting the nat ural eru ptive force, following the removal of the causative agent, it w ill be seen th at the bone supp ort of that too th w ill be greater tha n tha t aro und norma lly eru p ting ad jacent tee th (Ingber, 1974, 1976; Stern and Becker, 1980; Kohavt et al, 1984; Melson. 1986). Howe ver, this positive res po nse on the part of the alveola r bone to the extrusive forces is dependen t on the amo u nt of pressure applied being wit hin relatively narrow limits. A pe riapical rad iogr aph taken at that time w ill show radiolucen t areas whe re new bone is being laid dow n - new bon e does not show u p on X-ray. Howev er, a similar view taken 4-6 months afte r cessation of this movem en t, when the bone will ha ve matu red and calcified , will s how the excellen ce of its regeneration . In the eve nt that excessive extrusive force is bro ught to bear on these tee th, eruption will also occu r rapidly, but it will occu r withou t regeneration of alv eola r bone. The result will be cha racterized by the too th hav ing a long clinical cro wn an d conside rable mobility. A periapical radiograph performed even 6 mon ths later will show a muc h red uced bon e level around the newly and apparen tly su ccessfully resolved im paction. The prognosis of su ch a tooth will be im pa ired .

Type and height of periodontal attach ment Preservation of vitality

If the su rgeo n o pen ed a window in the oral mu cosa d irectly over the impacted tooth, above the attached gingiva , then the prognosis of the result w ill be relatively poor . Steps shou ld take n to manage the mu co-ging lva l so ft tissue properly, by liftin g a full flap from the crest of the rid ge at the time o f the surgical exposure and fully resut u ring the wound, at the end . In this wa y, the too th will come down with a normal band of attached gin giva, an d the periodontal result will be good.

Du ring the surgica l p rocedure, removal of aw kward ly placed su pernu merary teeth may cau se dcvitali zation of the impacted too th. Th is is qu ite u nusual, ho we ver, and it is more likely that excessive extru sive forces, which may be negligent ly applied to eru pt the tooth . This co mpromises its bony sup po rt, and w ill also bri ng about the d emise of its pulpal tissue.

Relative bone height of the crestal alveolus

Oral hyg iene

In C hap ter 6, we sh all show that when teeth Me su pe r-eru p ted, their vertical mov em ent is

During the initi al phase of eruption of an impacted too th, the surrou ndi ng gingiva is

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH -..::.::..:::-..::.:=-..::.:===---=--..::.:---=-=-=_

72

sens itive, tender and bleeds ver y easily. Th is w ill usu ally make the yo unger patient very

The dilacerated c entral inc isor tooth and the incisor with arrested root development

ap prehensive of brushing the area on a regu lar basis an d to an ad equate stand ard of cleanliness. Secon da ry inflammation of the gingiva and it concurren t adverse effect on the regen eration o f bone w ill be the ine vitable res ult. For these rea sons. care sho u ld be tak en in the proper p lanning and execution of the surgical techniqu e a nd in the application of extrusive forces w hose magnitu de are d ifficult to control. Elastic ligation thread is used widely for applying tr action to im pacted tee th, by tying it directly a nd tightly between attachment and a rela tivel y rig id archwi rc. It is exceptiona lly difficult to properly judge the amount of force be ing ap plied by this me thod, and so, when it is the only practical one available, great carl' should be taken not to til' too tightly. Wherever possible, alt ernative met hod s should be used, as d escribed in Chapter .I . Vertical 'bo x' elasti cs arc often used in ort hodonti cs to enha nce lntercusp ation at the close of treat me nt , in routine cases. These clastics arc s mall a nd ca n p roduce forces very much in excess of thnt d esirable for a singl e impacted too th, and these will be increas ed still furt her by mouth openi ng. It is difficult to measure or con trol the forces applied in this way . Nevertheless, thi s is a va luable too l, and sho uld be u sed w ith only the ve ry lightest an d larges t of elastics. It shou ld also be remembered that . as orthod ontists. we are apt to apply mo re th an adequate extrusive forces by th e downward d eflection of an archwire, and we then place a 'box' clastic, in addition, ju st to be sur e! The ag gregated force beco mes very mu ch in excess of the physiological lim it.

It is clear tha t the long-term prognosis of many dila ccra tcd teeth and teeth with arres ted roo t dev elopm en t is poo r an d the ir extraction and replace me nt is proba bly a pa rt of the long-t erm treat me nt strategy. This being so , the mos t pe rtine nt of questions that need s to be asked rega rdi ng the d ilaccratcd too th is whethe r it is worth it. The an swer to the question is not necessari1y the sa me for every case, and each must be conside red on its own merits. -No decision should be made until the p ractitioner firs t considers the following po ints in relation to the particular patient concerned.

Impaction d ue to trauma Soft tissue obstructio n

The on ly treatm en t nccdc.....i to overcome the rcsisten ce of the thickened mucosa to eruptio n is s u rgical, and was desc ribe d in Chap ter 3. BI8 L JOTHE'Q UE: DE L'UN1''ERSlT~ OS: F'ARIS V

U.ER. D' cO)ou rOLO GI '= 1.

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92 12 0

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I

~ rv' '' x

:~ lI,JNTH O U G E

(a) A pe rmanent artificial solution cannot be considered much before early ad ulthood, whether by conventional prosthod ontic trea tment or im plan t-bo rne restoration. (b) Any tissue-bo rn e for m of temporary replacement (partial 'flip pe r' denture) will be far less sat isfactory from every poin t of view. ( c) An y too th-bo rne, resin-bo nded br idge replacement may requ ire so me prep aration o f the adjacent tee th, and ma y be unreliabl e in the long term (Boyer an d William s, 1993). (d) Follo wi ng the extraction of the d tlacerated toot h, the alveo lar ridge area is deficient both vertically and in its labioling ual width, making the case u nsuitable for an im plan t and unaesth et ic for a conventional bridge. (e) Orthodontic alig nment of the d tlacerated tooth will bring with it much alveo lar bone, to enhance bot h ridge wid th and vertical heigh t, to normal dimensions. (f) The retention o f even <1 very short-ro oted and endodon tically trea ted tooth will p rese rve the norma l shape and ar chitecture o f the alv eolar rid ge. Und er these condi tions, or thod ontic align men t of the impacted an d dilarera tcd too th will u su ally be p refe rable, even if sp lin ting o f th is compromised too th is needed to give it s upport. For the most par t, however, th is proced ure must be loo ked upon as provid ing

73

MAXILLARY CENTRAL INCISORS

on ly a tem po rary solution, and, a t a later time, w hen gro wth has ceased and cond itions are more favourable, so me form of pe rmanent res tora tion will need to be considered. Ap ica l root d ilaceration

In the ve ry you ng pa tient, trea tment of th e dila cerated inciso r follows much the same lines as d escribed for the obstructed incisor. Before this is don e, how ever, a carefu l study of the tangen tial rad iogr aph may reveal the .shape and orientation of the root. The more apica l the d ilaceration vis-a-vis the coro nal third of the roo t, the be tte r the prognosis. On the other hand, if the d ilacer ati on is in the crown of the too th. the prognosis imp roves the closer it is to the incisal edge. If the d ilaceration is situa ted apical to the coronal third of the root. orthodontic alig nment will p rovid e an excellen t prognosis. The too th should be surgicall y exposed an d an eyelet bond ed to it. In most cases, the only surface of the crown that is availab le for the eyelet is th e palatal surface. This faces the opera tor when the too th is first exposed , wh ile the ana tomically labial surface of the tooth is inaccessible, facing s upe riorly and posteriorly and buried in the hard tissu e of the an terior nasa l s pine (Fig. 5.8). A stainless steel ligature is thread ed through the eyelet. twisted into a pigtail and d rawn do wnw ard s, to be ligated to the main ar chwire wit h a horizontal elas torneric mod u le, as described in Cha p ter 4. Care should be taken not to apply mu ch pr essu re initially, sin ce the tension introd uced by su tu ring the surgical flap may itself apply a considerable dow nward for ce to the tooth in the first few week s. As the cro wn of the toot h responds to the force, it rotates do wn wards marc and more. At the same time, the ro ot ape x rotates forwards toward s the labial plate of bone. In general, the case may be com pleted witho u t the root apex ev er becom ing pal pable in the labial sulcus. O nly in exceptiona l circum stances, w hen the roo t curvatu re is very acute, will this po ss ibility become a reali ty . If the apex is prominent an d further lab ial root moveme nt is still desi rable, this will necessitate a surgical interven tion, performed

with the aim o f ampu tating the roo t apex of thi s tooth. The labially d irected po rtion of the root. corres pond ing to the post-tra umatic d evel opme ntal portion. is secti on ed in a line that is con tinuous with the labi al side of the main coronal po rtion of the roo t of the too th. The pulp is extirpated an d the roo t canal is obliterated using a combined conventional (coronal) and retrog rade endodontic approach. whe rever possible (Fig. 5.12). Further extrusion an d appro priate root to rqueing of the inciso r may necessitate a second roo t-sho rtening pr oced u re. but, if the first proced u re was delayed. as late as possible and the roo t ape x amputati on was properly designed, this may u sua lly be avoided. The d egr ee by which the fina l pr ognosis of the sho rt-rooted central incisor will be comp romised d epend s largely on how much roo t remains after the amputation has been perform ed . The site of the ampu tation is entirely dep end ent on the location of the dil acerat ion, an d it eliminates a majority of that portion of the root, apical to it, tha t had dev eloped after the trau matic episode. Thus the closer the dilaceration is to the coronal portion of the roo t, the shor ter will be the fina l roo t len gth at the completion of trea tme nt and the poorer its prog nosis. Crown d ilaceration

Dilaceration may also occu r in the crown portion of the tooth, as has been ind icated earli er. In this eve ntuality. the tooth itself Illay not be so seriously d isplaced labially. When the crown is surgically exposed. an attachme nt is best placed on the labi al surface, wh ich is almost certainly accessible. In this way, the continued d ownwards-di rected or thodontic traction will bring the root portion of the tooth from its mo re pal atally d isplaced location, close to its norma l positio n and its lon g axis within normal limits. This will be due to the lingual tip pi ng effect of the attac hment on the lab ial surface. The too th will erup t with th e more incisal sec tion of its crown lab ially tip ped an d th e po st-traumatic section in a n acceptable an gulation . Res torative treatment is indica ted after grind ing off that po rtion of the crown that

THE ORTHODONTIC TREATMENTOF IMPACTED TEETH

74

represents the p re-tra uma d ental de velopmenta l portion . The fut u re o f the too th will then be founded on the majority portion of the tooth. w hich developed su bsequent to the traumatic episode. Roo t ca nal treatment ma y be required. and the ideal contour of the tooth restored us ing a crown and co re res toration. Rarelv, the d ilacera tion site ma y be found to be incisally pla ced, in w hich case a mo re modest com pos ite material res torat ion may be used , with vita lity main ta ined . In either C,lSC , the initial crown reconstru ction tha t is placed sho uld be ma d e in ,1 line con tinuous wit h the long ax is of the root portio n a nd an or thod ontic bracket bond ed to its appropria te mid -lab ial position, read y for finishi ng . Fina l root alignment, in both the labio-lingual and mesio -distal plan es, is then achieved in the usual manner for the particular a p plia nce system bein g used .

The critical portion of the too th for the d ilacor..ation to occu r is the coronal part of the root,

clos e to the ccmcn to-cnamcl junc tio n. In thi s situa tion . the prognosis of the aligned too th is extremely poor, since the major ity o f its roo t, that rela ting to the post-trauma period of development, \\;11 need to be amputated d uring the procedure. lea ving the too th wi th a non -viable coronal remna nt of the root. Such a tooth will need to be extr acted . Nevertheless, it will be necessary to reopen the s pace in the denta l a rch for so me form of artificial replacement. Accord ing ly a nd reg .ardlcs s of the progno sis, the sa me prepara tory or thodontic p rocedu re is still advisable. A modified John son' s tw in-w ire a rch ma y be p laced a nd space opened up as accurately as possible, to provide e xactly the right a mou nt, by compari ng it with its erupted a ntimere. At this po in t, the dilnccrated too th is exposed, an d. if its condition is confir med as ho peless, it may be extracted, bu t not disca rd ed! Instead , its contorted TOot is ca refully severed from the perfectly sha ped CTOwn w ith a high-speed d ia mond bur, and the pulp chamber cle a ned and filled with a com pos ite filling ma te rial. The newly p repared natu ral

(.,

(hI

wry

Dilaceration of the coro nal third of the root

Hg ure 5.12 Tangontia l \'io>w~ of tho> com pleted alignmen t oi a dil acerat cd tWlh with mo' ca n al filling (,1) prior to and apkectotny an d rerrograd e dllld l~m iill in~. (Courtesy of Dr I Hl'linK & Dr \ 1 \1 " r.lg J

(b)

afte r

75

MAXILLARY CENTRALINCI$QR$

,:'=.. , ~ ,

•"

~,

': . . . . , . \

~

1.1

I '

\l i(

II! .' ' ." .11.. '

·l l ;

:,

·

~.l · · ~'

'1'1: r

'

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Ib)

figure 5.13

t,,) I' m :i,,'ly meas ured re"'0l-.,.,nin~ of tIll' ~ Pi\","' is performed . using a remov able applia nce. (h I The prepa red crown uf the dilaccrat c n 'ntrJI incisor, shown in Fig. 5A, is bonded between thc e tch... d inte rproxima l surfaces of thl." adjacent teeth.

crown ma y then be bonded to the tw o adjace nt teeth. to act as its own space main taine r (Becker ct al. 1976), until a mo re s atisfacto rv pe rmanen t replacemen t may be made, which, in view of the patient' s age, ma y not be for se vera l yea rs (Fig. 5.13). Alte rna tively, a nd provided that th e a pical po rtion of the roo t is s ubsta ntial, it ma y be ad va ntageous to treat it in the ma nner of a cro w n dilaceration, To achie ve thi s, it w ill be ncccss arv to remove the CTOwn of the too th at the tim e' of surgical exposure and to pe rform a n im media te root cana l filling . A fixed , threaded pos t is p repa red and a sma ll hole is bo red th roug h its co ronal end. The po st is the n firmly p laced. The roo t surface an d m uch of the co ron al pa r t of the po st a re covered wit h a com posite filli ng ma teria l, leaving the tip of the post exposed , A stain less steel liga tu re wire is passed through the prepared hole a nd lightly tw isted in to ,1 pigtail w ith the help of a r tery forceps. In the abse nce of the acu tely a ngled crow n portion, the remai nder of the too th presen ts a less complica ted im paction, whose resolu tio n is s traightforwa rd . The prepa red too th is e rupted in to the mouth unti l th e post an d the res tora tion covering the roo t su rface bec ome apparen t at the gingiva l level. The o rie nta tion of the roo t of the tooth is then reassessed by palpation a nd by taking new ra d iographs - ,1 pe riapical for

the mesio -d ista l inclina tion and a tangl'llti al for the bucca- ling u al rel a tionship . The la tte r vie w w ill bt> con sidera bly easie r to d iscern tha n be fore, sin ce the roo t 'canal filling w ill act as a n excellent rad io-opaqu e ma rker . The p atient is no w referred for a ny neressary a nd appropriate muco-g tngiva l surge ry by a competent pe riodontist followed by the construc tion of a good q uality temporary acryli c crown, wh ich is pla ced over the e xistin g po st. A general dentist or a specialist pro sthodontist is familia r w ith the need for 'correc ting' an abno rmal root orien ta tion by placing the artificial cr own in lin e w ith the crowns of the ad jacent teeth, rega rd less of the root axis. This may be a sens ible com p romise in the mo re mino r non-im pacted displa cement cases, since orthod on tic ro ot movement mav then be a voi ded , However, in dil acer ation cases, conside ra ble root movement is needed, and thi s is most su itably per formed with the existing or thodontic a ppli an ce. For this to be mad e pos sible, the te mp orary crown m ust he p laced a t a n angula tion a ppropria te to the rece ntly confirmed long-a xis or ien ta tion of the roo t. Th e desired orie nta tion of th is int ended reco nstruction of the cro wn of the too th w ill not be in line w ith its neighbours, a nd this is not always a n ea sy mes s age to convey to the pros thod ont ist! O nce the tem po ra ry a rt ificial restora tion is in pla ce, a bracke t is placed in the usual manner. C rown

76

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

alignment and roo t torq ue an d uprig hting are then u nd ertaken. It may be seen that the po in t beyond which a root amputa tion should be a voided is when less th a n one-th ird of the roo t will remain after trea tment. Cro w n a m puta tion may be used as a viable altern at ive up to tha t point, but it m ust be remembered tha t the re maining root portion, which may be as little as

one-ha lf to two-th ird s its orig inal leng th, will be na rrow er in bo th mes io-dista l a nd buccolingual d imen sion s, which will make the place me nt of a satisfactory crown more d itficu lt to achieve. It is em phasized that , once the space in the ar ch has been gained a nd the tim e has come for su rgical exposure, accurate d iagnosis of the exact location of the dilaceratio n is critical if a valid decision is to be made. As pointed ou t earlier, this is not alw ays possible fro m the radi ogra phs, owing to the su per im position of other unerupted teet h an d neighbour ing roots on the ta ngential view. The periapical view can contribu te nothin g in this respect. If it is still im possible to loca te the dilaceratio n then an a ttachment should be placed on the lingual sid e of the tooth, as before, an d the initial traction appli ed to bring the cro wn o f the tooth occlusally. A decision to amputa te the roo t portion of the tooth m ust , in an y case, be d ela yed until the root is palpable, bu lgi ng into the labial su lcus. At each su bse quent visit, the sulcus should be carefully chec ked, an d any palpable cha nge in the positi on of th e roo t a pex in this d irection should be compa red w ith the downwa rd progress and eruption s ta tus of the cro w n and its angula tio n. Prow ess rad iographs should be ta ken at appropria te stag es, u ntil the exac t location of the dila cer ation may be p inpointed or ot herwise clinically diagnosed , par ticul arly in relat ion to the long axes of the tw o parts o f the too th. O nce the accura te d iagnosis ha s been es ta blished, a reassessmen t of the trea tme nt a pproach s hou ld be mad e to decide w het her th e line of trea tment is indeed appropria te or w hether the crown po rt ion should be a mputated and the directio n of traction alte red accord ingly.

ACUTE TRAUMATIC INTRUSIVE LUXATION Following trau matic in trusive luxa tion, the affected too th may re-erupt and may eventu ally retu rn to its original position (Sha pira et al , 1986). In other cases, however, th e tooth re ma ins intruded a nd ma y require o rthodontic assistance to encou rag e re-cruption. For these cases, the e mergency trea tme nt a nd some initial res torative procedures will already ha ve been carrie d out by the paed od ontist or the oral su rgeo n, and the pa tie nt will not be in pa in a t the time tha t orthod on tic assis tance is required . For this tooth to ' take' and be s uccess ful, the d esired union of tooth to the su rround ing bone is by he aling alo ne or by healing w ith surface resorption. Accor ding to A ndreasen and Andreasen (1994), healing w itho ut sur face res orp tion is probab ly not a po ssibil ity in the clinica l situa tion, since it must be comple ted tot ally w ithout inju ry to the Inne rmos t layer of the periodonta l liga me nt. How ever , he aling w ith surface resorption w ill lea ve the lu xated too th a tta ched to th e soc ket w ith a normal periodontal liga ment a nd new cementum. Such a tooth wi ll respond to ort hodontic forces . If, on the othe r ha nd, healing is by replacement resorp tion, there is a d irec t union be tween the roo t a nd the su rround ing bo ne. Repair w ill be counted as successful, but the too th will then never be a menable to orthodontic forces . The too th may so metimes regain a normal a ttachmen t (a tran sie nt re p lacemen t resor p tion), altho ugh thi s is by no means ce rtain, a nd it is probably more like ly that a reas of ankylosis w ill occur over the root surface an d th e too th will then remain in trud ed permanentl y . Th e too th, as it sta nds, is then of no va lue to the dentition, nor is it us eful as a fou nda tion for lasting p rosthodontic res toration . Under these cond itio ns, its extractio n w ill be indica ted . O rthod ontic in terve ntion a t the appropriate time ma y offe r the only viab le tre a tm ent option tha t, together with certa in rela tively minor res to rative p rocedures, may p roduce an excellent result w ith a fai r p rognosis. If the too th is still complete ly su bgingival th en the

77

MAXILLARY CENTRAL INC ISO RS

",

'd

(dl

(,I Figu re 5.14 (,1) Acute intrusion o f ,1 m,ni ll,l ry ldl and crown fracture o f the ma xillary rig ht central incisors. (bl T he ta ngen tia l radiograph shows intrusi ve and buccal dis placement. (c) At ]4 days post-tra u ma, a but ton at tachment is bond ed to the intruded incisor. The labia l arch is activa ted to ex trude the too th a nd the pa tien t is instructed in accu ra te plac~'ffien t"lOd can'. (d,c) The tooth hil" re-eru p ted . Bo th cen tral inciso rs have had root ca na l trea tmen t an d crown restoration. (Co u rtes y " f Dr B I'en 'tz.)

78

_

_

_

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH _ _ _ _ _ _------'=...:.....c--=..::..:.------'=---=---=-----------=--==__=:.._

labia l soft tissue w ill need to be su periorly repositioned, un til 2 mm of the incisa l edge of the too th is reveal ed. Light extrusive force must be applied after the lime that the periodontal fibres have begun to re-unite a nd in the earlier stages of the organ iza tion of the blood dot, but before the la ying d ow n of bone, i.e. 10-28 d ays pos t-trau ma . Special ca re must be exercised when us ing fixed applia nces in thi s situa tion (Andreasen a nd Andrea sen, 1994). Firs t, w ith or w it ho ut

the use of orthodontic brackets, some kind of resistent fram ework need s to be bo nded to the adjace nt teeth, which act as a multip le a nchor unit fro m which for ce would be a pplied to the intruded too th . Th is cou ld take the form of a few brackets and an archwire,

althoug h the composite bonding of wire d irectly to the labial enamel of these teeth wo uld be more sa tisfactory fro m many points of view . Unfortunately, these teeth the mselves will almost certainly have been

[a ]

foJ

Cd)

Fij;llre 5.15 (a.b) Fron t an d le ft "j e ws, s howing pal atall y di spl aced cen tra l incisor, I we-ek pos t-tr auma. Th e crow n red uctkm is clt'arly seen. k .dl Mod ified Jo h nso n's twin-arch a p plia nce in place . Bucca l coil sp ri ngs apply labia l tip pin)o\ fu r.....• on the "'inglt' 0.018" ar chwi re, wh ic-h e nsas'''' the br ae-let of the d isplaced too th. (e,O A torq ueng a uxiliary is laced down to the main a rch wire and 1iC\l back to the molar tu bes. (g-il 12 mo nths after co mpletion of treatment: fron t an d left v iews of thl.' occlusjon and a close- u p vie w of the ma xilla ry cen tra l incisor teeth . (j,kl Tan genlial "nd po..' l'i.1pica l p retrea tmen t \; ew ". (I,m) Ta nge ntia l a nd pe ria pical views 4 weeks late r. (nl Periapical view at 12 months shows obli tera ting vita l pulp.

79

MAXILLARY CENTRAL INC ISORS

(e)

(8)

(h )

(fig ure 5.15 ...>U li"'....n (j)

80

_ __

_

_

_

_

_

_

_

_

____=-cTHE ORTHO DONT IC TREATMENT O F IMPACTED TEETH _=_~

(Figure 5.15 continued )

,k)

(j)

(m)

111

(n)

MAXILLA RY CENTRAL INCISORS

trau mat ized at the time of the accident, an d using them in th is manner ma y lead to furth er d am age, even at th e lig ht force levels involved. Second ly, if the intended extrusion is pe rformed more tha n 2 mont hs ,posttrauma, ankylosis may have affected the target tooth (And reasen and Andreasen, 1994). Active extrusive forces gen erated by the appliance will then be of no avail. Instead , the reactive forces will be absorbed by the ad jacen t anchor teeth, and these will become intru ded . Simple remo vable applian ces (Fig . 5.14) are mos t su ita ble, since they need apply no forc e to the ad jacen t tee th, which may also have been damaged in the traumatic expe rience (Peretz et al, 1982; Member. 1994). A small button atta ch ment is bond ed on the labial side of the too th and the lab ial bow of the remov able ap pliance is d ivided at the mid line and activated vertically downward s against the button. Tre atmen t generally proceed s rapid ly, with the too th appearing in the mo u th and at the lev el of its neighbo u rs with in a few weeks, d ependi ng on the amo unt of extrusion requ ired . Once the too th erupts, root canal therapy is u sually ru..ceded. and a pennane nt restora tion may be pla ced , followed by a short pe riod of retent ion . Intru d ed teeth whose root development is completed are generally scheduled for roo t trea tme nt in the first week after the traumatic incid en t. Under id eal circu ms tances, orthodon tic trea tme n t o f endod ontically trea ted teeth is no t normally advised unt il they have been followe d up for several months an d until the re is some rad iogr aph ic evid ence of repair. However, following in trusive trauma, the possibili ty of th e occu r ren ce o f ankylosis (repla cem ent resorption ) is significan t, and will be evid ent wi thin two mont hs. Th us the exception al circumstances d icta te th at the or tho dontic extrusion of these tee th mus t begin , at the latest, six weeks or so after the trauma tic episode, altho ugh the IG-28·d ay time frame is to be preferred . The risk of failure of extrusion d ue to repl acement resorption is hig h and absolute, which is why treatment sho uld begin within this time. The risk of an orthodontically ind uced need for root trea tmen t is much lower and of less the rapeutic significance.

81

Once the too th has been brough t into alignme nt, it may be-retained an d splinted to its immed ia te neighbo urs, using a short length of multistranded wire, which is bo nded to the lab ial surface of the three teeth , for a few months on ly. It is important not to cover the wire comp letely w ith composite materia l, bu t to p lace a small blob of composite material across the wi re over eac h too th an d to leave broad areas of exposed and flexible wi re. Rigid bond ing for long period s is contrain dicated , since it seems to lead to a grea ter incidence of pulp necros is and p ulp obliteration (Andreas en and Vcstcrgaard Ped ersen , 1985; Rock and Grund y, 1981). However, the mu ltistranded wire spli nt allows a d egr ee of mo vemen t, which is sim ilar in extent to that !ieen in p hysiol ogical mobility (Becker, 1987; Becker and Gou ltschln. 1984; Zachr isson. 1977; Dahl an d Zachn sson. 1.991), and thu s may p robably be safely used for con side rably lon ger. Ap propria te res tora tio n may be undertaken be fore or after this splinting has been comp leted . A child may su stain a severe blow to the premaxillary area , d isplacing a maxillary cen tral incisor in suc h a ' v ay th at the crown is tipped inwards and the root protrud es th rough the alveolar bone. The pa tient is unable to close the teeth together, owi ng to prematurity on the d isplaced too th. In the heat of the momen t and lack ing su itable d irection , the paren ts of a child do not al ways attend the appropri ate clinic or the mos t knowled geable d ental practitio ne r. The emergency treatment ind icated for this case is to ma nip ula te the too th to its original site, under 10C,ll an aest hetic an d to sp lint it in p lace. The pa tien t shown in Fig. 5.15 wa s trea ted by grind ing the incisor to red uc e the occlusal in terferen ce, and wa s given ,1 bite p late to disa rticu late the teeth! When the paren t was finally referred else vv-her e, seve ral da ys had elapsed and manipu lative red uction of the d isplacement wa s no longer approp riate. O rthod ontic trea tm ent wa s p resc ribed to resi te the too th by applying labial tip ping and then palatal root torque. Since th is involved its being moved thro ugh freshly organizing blood clot, the trcarnent proceed ed with great speed . The too th maintained its vitality, as

82

_ _ _ _ _ __

_

_

evidenced by positive pulp tes ting an d by pulp oblite ration . Finally, the grou nd-down crown was improved with a composite restoration, and follow-u p periapical radiogra phy will determine whethe r root resorption occurs and if ap p ropriate root canal therapy will be needed .

_

THE ORTHO DONTIC TREATMENT OF IMPACTED TEETH "-'---.....::..::..::--"-.:...:..=.:..:=:c='--.:.:.:~

its etiology and treatment. I Dent CI/i1d 43: 352-6. Brook AH ( 974) Den tal an omalie s of number, form and size: their prevalence in British schoolc hild ren. I lilt AS${J(' Dent Child 5: 37-53. Dahl EH, Zachrisson B (199t) Long-term experi en ce wi th direct-bonded ling ua l retainers.1 Cun Orthad 25: 619-30.

REFERENCES

Day Re B (1964) Supernumerary tee th in the prema xillary region . Br Dent 1 11 ~ : 304-8.

Andreasen 10 , Andreas en FM (1994) Textbook and Color Atlas of Traumatic Injuries to the Teeth. Munksga ard, Copen hagen .

Di Blase DD (971) The effects of varia tions in too th mo rp ho logy and position on eruption. DCIl I Pmct o-« Rec 22: 95- 1OR.

And reasen RM, v crstergaard Ped ersen B (1985) Progn os is of luxa ted pe rma ne nt teeth the developmen t of pu lp nec rosis. Ended Dent Traunmtotv: 207-20.

Gard ine r jII (961) Supernum erary teet h. Dellt Pract Denl Rec 12 : 63- 73.

Battagc l 1 (1985) The case for early assessment : 2: trea tmen t with s pecialis t support. Denial Update 12: 293-8.

Ho usto n WJB, Tu lley WJ ( 986) A Textbotlk of Orthodontics, p p 126-31. Wright, Bristol.

Becker A (1987) Periodontal sp lin ting wi th multistrand wire follow ing orthod ontic realignment of migrated teeth: report of 38 cases. l1/tl J Adl/lt Ort}wtl OrtllOX" 511rg 2: 99-109.

Om t Prod Dm t Rec 17: 332-42.

Becker A, Go ul tschin J (1984) The mult istrand retai ne r and s plint. Am I OrtJw(/ 85; 47()-4. Becker A, Stern N, Zelcer Z (1976) Utilization of a dil acerat ed incisor too th as its own space mai nt ainer. I Dellt 4 : 263-4. Becker A, Koh avi D, Zilbcrman Y (1983) Per iodon tal status following till' ali gnment of pal at ally impacted cani ne teeth. A m I Orthod 84, 332-6 .

Bodc uha m RS (1967) The treat me nt and prognosis of un erupted maxillary incisors, associated with the p rcsc nce of su pe rn u merary teet h. Br oo« 1 123: 173-7. Boyer DB, Williams VD, Tha yer KE (]993) Analysis of debo nd ra tes of resin-bo nd ed prost heses. I Dellt Res 72: 12~ . Brin I, Zilbcrman Y, AZ,lZ B (1982 ) The unerupted ma xilla ry centr al incisor; revi ew of

Hotz R (1961) Ort hodontia in EI'avdml Practice. Hube r, Berne. . .

Howa rd RD (]967) The unerupted incisor. How e GL (971) Millor Oral Surgery, 2nd edn, pp 135-7. Wri gh t, Bristol. Ing be r sj ( 974) Forced. eru p tion. Part I. A me thod of trea ting iso lated one and two wall inf rabo ny osseous defects - rati ona le a nd case repo rt. I Period 45: 199-206. Ing ber SJ ( 976) Forced eruption. Part II. A method o f treating non -rest orable teeth periodon tal and restor ative considera tions. I flaiod 47: 203-16. Johnso n JE (1 934) A new or th odonti c rne chani srn : the twi n wire alignmen t appliance. I n/em il! I Ortncd 20: 946-63. Kettle MA (1958) Unerupted uppl'r incisors. Tmlls Eur Unhad Soc 34: 388-95.

Kohavi 0 , Becker A, Zilbcrma n Y (1984) Su rgical exposure, orthodontic' mov ement and final too th position as factors in pe riodontal breakd own of trea ted pala tally impac ts..'CI. canines. Am i Drthod 85: 72- 7. Mambcr EK ( 994) Treatment of intruded

83

MAX ILLARY CENTRAL INC ISO RS

perman ent incisors: a multidi sciplinary appr oach. Eudod DCllt Tral/lllalo/ 10: 98-104.

Shap ira J. Regev L, Liebfeld H (1 986) Reeruption o f comp letely int rud ed immatur e permanent incisors. Eudoll D ent Traumatot 2:

Melsen B (1 986) Tissue reaction following a pplication of ext rusive and intru sive forces to tee th in ad ult monkeys. A m I Orthod 89: 469- 75.

with the Tw ill- Wire Appliallce Mosby, St Louis.

Mills JRE (1 987) Prillciples and Practice of Or tJlll(ftlllticS. 2nd ron. Ch urchill Livingstone, Edinb urg h.

Stem N , Bec ker A (1980) Forced eruption: biological and clinica l conside r..arions . I Oral Relmbil 7: 395-402.

Mitchell L, Bennett TG (1992) Supern umera ry teeth causing delayed eru ption - a retrospective study. Br I Orthod 19: 41--6.

Stew art OJ (1978) Dilacera te uneru p ted maxilla ry cen tral inciso rs. Br Denl I 145; 229-33 .

I

maxillary an terior su pern umerary teeth: repo rt of 204 cescs. J Dent Chifd 51: 289-94.

Pere tz B, Becker A, Chosa k A (1982) The reposition ing of a traum atically-in truded mature rooted permanent incisor with a rem ovable appliance. J Pedodont 6: 343-54.

Witsenberg B, Boerin g G (J98J) Eruption of impacted permanent upper incisor teeth after removal of su pern ume rary teeth . J Oral SI/rg 10: 423-3] .

Rock WP, Grundy MC (1981> The effect of luxation and sublu xation upon th e p rognosis of traumatized inciso r teeth . I Dellt 9: 224-30.

Zachrisson BU (]977) Clinical experi ence wit h direct-bonded orthod ontic retainers. Am I

Sewa rd GR (1 968) Radio logy in general dental practice. IX - Unerupted maxillary canines . cen tral incisors and supe rn u meraries. Br Dmt 1 115: 85- 91.

Zilberm an Y, Malm n M. Sh teyc r A (J992) Assessme n t of 100 children in Jerusalem with supernu merary teeth in the p rema xillary reg ion. J DCllt Child 59: 44- 7.

Mu nns 0 (1981) Uneru pted inciso rs. Br OrO/(/(1 8: 39-4 2.

11 ~16.

She pa rd ES (1 960 Technique and Treatment

Tay F, Pan g A , Yuen 5 (1984) Une ru pted

Orthod 71: 44o-B .

6 PALATALLY IMPACTED CANINES

CONTENTS • Prevalence • Aetiolo gy • Complication s o f the untreated Impac ted cani ne • Diagn o si s • Treatm ent timing • General pr in cip les of mechanotherapy • Th e nee d for cl assifica tion of the pal atal c ani ne • A cl as sif ication o f palat all y impacted cani nes

PREVALENCE In any population, the preva lence of pa latally impacted maxillary ca nines is low, but it see ms to have a variable d istribution with regard to eth nic orig in. The low est frequency reported in the lite rature relat es to the Japanese (fakahama an d Aiyama, 1982), where the anomaly occurred in onl y 0.27% of

the sam ple population. Some very ear ly studies by C ramer (1929) am on g wh ite Ame ricans and Mead (1930) in an und efined sa mpl e found 1.4% and 1.57% respectively. A study of a lar ge series of full mout h denta l rad iographs among pa tient s in the USA revealed a figure of 0.92')1" (Dachi and Howell, 1961), while Brin ct al (1986), in a s tudy o f an Israeli popu lation, found a level of 1.5'X,. The highest figu re for the anomaly fou nd in the more recent su rveys, 1.8%, has been rep orted in the stu d y by Thi lan d er and Jacobson (1968), of an Icelandic popu lation. Montelius (1932) was the first to ind icate a d ifference be tween Caucasian and Oriental popu lations, altho ugh he found a frequency of 1.7% for Chinese and 5.9% for Caucas ians. However, since he did not d istingu ish between buccal and pal atal impaction in his

study, little usefu l informati on ma y be gleaned from these figures in the imm edi ate context. More recently, the work of Oliver ct al (1989) has indirectly indicated that Asians ma y su ffer from buccally impacted canines more frequentl y than from palatal canines . While th is appears to be sup po rted by various case reports th at haw appeared in the literature from the Far Eas t, no definitive stu dy ha s been undertaken to investigate this p ossibility. A strong prevalence of impacted canines is fou nd am ong females, with a ratio of 2.3 : 1 (Dac hi and Ho well, 1961) in the abovementioned group of Am erican pa tients, 2.5 : 1 (Becker et al. 1981) in an Israeli orthodontic group, and 3: I in both a Welsh or thodontic group (Oliver ct al, 1989) an d in a US or thod on tic sam ple (joh nston, 1969). However, some con fus ion ex ists with regard tothese figures, since a random Israeli population s tudy (Brln et al, 1986) ha s shown an approx imately eq ual male-fem ale occu rrence of the an oma ly. Furthermore, O liver ct al (1989) have ind icated tha t, although a higher female incidence wa s p resent in their study of Welsh patients, this reflected the trend for more females to seek orthodontic treatme nt in the UK.

86

THE QRTHOOONTIC TREATMENT OF IMPACTED TEETH

- - -- - - - - -- -- - - - - -- - - - -

(, )

Figure 6.1 (a) An terio r occlusal vie w sho ws an im pact ed can ine. an odomo me and a missing la l~'ral incisor. (b) Pe ria pical \'iew of impacted canine and first pre molar associa ted

with en odoruome and over-retained decld cous first molar. (b )

If we are to ass u me that the motivation for th is is that girls are more concerned w ith

improving their appearance then the diagnosis of an impacted maxillary canine, given the presence of an over-retained . decidu ous canine, is not usually the cause for the patient presenting for orthodontic treatment. Appearance is rarely mar red by this, since there is a comp lete and u ninterrupted di splay of teeth, and any abnormalities are u sua lly not d isfiguring. Mo tiva tion for treatmen t m ay therefo re rather depend on the ability and persuasiveness of a pa rticular practitioner in pointin g ou t the po tential haza rd s of no ntreatmen t. There may be no basis to expect that this wo uld con vince mo re female pa tien ts than males to accept trea tmen t.

tal origin (Fig. 6.1) will un d oubt ed ly prod uce abnorma l position ing of an u neru p ted pe rmanen t maxillary canine, bu t they a re com pa ratively rare in the canine area . The fact that the majority of im pa cted canines occu r in their abse nce compels us to look elsew here for the main causes o f im paction. To explain the mecha nism o f palatal di splacement of the maxilla ry can ine, so me of the hypo theses that have been pu t forw ard have bee n int imately invo lved with aberration in the normal process by which the maxillary an terior tee th eru p t. For this rea " 011, an und erstandi ng of norm al d evelopment in this area is im portan t

Normal de velopment

AETIOLOGY There is no single cause of the palatal di splacement of the maxillary canine toot h. Space-occu py ing, extraneous ent ities of den-

In the midd le pe riod of the de ciduous den tition, a per iapica l rad iogra ph of the p remaxillary region will show thc fully compl eted de cid uo us incisor roots. It will show the ove rlap ping shadows of the permanen t centra l

87

PALATAllY IMPACTED CANINES

an d lateral incisors, more or less in the same horizon tal p lane (Fig. 6.2.1 ) as the ap ical half of the root s of the deciduous inciso rs, with the canines being sited higher up_ The overlap of the pe rmanent teeth crowns is due to the fact th at these relative ly wide pe rm anent tee th arc all contained in a narrow area and.

,.)

at this time, a re in itia lly located palatally in the alveolus. The develop me ntal position o f the lateral incisors is palata l with relation to both the cen tral incisors and to the pe rmane n t canines. For these reasons, the peri apical view d escri bed above gives the appearance of severe crowd ing.

(b )

,-

Figu re 6.2 (a) A periapica l view o f maxillary pe rmam'n t incisor, ,It age 3 yea rs . Notl' th c J egl"l-'l' of overla p o f u neru pted !-"-'rmanc nt cen tra! and lateral incisors. (b) Thc sa me p,llil'nl at 5 yea rs . The per manent cent ral inciso rs ha ve migra ted inferiorly and labia lly relative to thl· la lerJI inci".,r.;. Nol l' the reduced Jl'~n.'l' of inci so r o,-erl.lp_ (e) Th,' u 'nl.al incisors all.' ,'rupli ng .It .lg" 6.5 years. N ote how the late ral incisors MW m igr .lll-d labially into the arch to clirmnate the O\·".I.lp evrn pl" lely. (Co u rtesy of Dr B l'e rMz.)

,<)

THEORTHODONTIC TREATMENT OF IMPACTED TEETH

88

During the early erup tive movements of the central incisors, a progressive resorption of the roo ts of the d ecid uous incisors occurs. The pe rmanent inciso rs m igrate slowly across

from the palatal side of the arch to the labial. as they proceed in their downward path, un til the teeth erupt into a more labial perimeter than wa s defined by the decid uou s incisor teeth bef ore their shedd ing. Du ring th is p rocess, the wide crow n po rt ion of the cent ral incisors will have moved dow n ward s and labially (Fig. 6.2b). As thi s occu rs, th e pro-

gress ively narrower eEJ area and then roo t portion of the central incisor come to lie

mesial 10 the unerupted lateral incisor crowns. This lead s to the fairly rapid p rov ision of space at this level in the alveo lus (Friel, 19-19). The lat eral incisor m igrates labially in to this a rea as it begins its downward erup tio n pa th. Additiona lly, the dow nward erup tion moveme n t d istan ces it fro m the pe r· manent canine crown, p rovid ing mo re space for it to move lab ially, following closely beh ind the central inci sor. With the er u ption of the cen tral incisors, the later al incisor crow n s move from a lingua l relation sh ip into a d irect d istal rel ationship wit h the central incisor roots, initi ally at a h igher level (Fig. 6.2c). As this occurs, the p resence of the lateral incisor crowns disp laces the developing ap ical area of the cen tral incisors towards one another, since these are at the same level, within the alveolar bo ne. With the cent ral incisor apices he ld tog ethe r in this way, the crowns of these tee th are flared d is tally . A d evelop men tally norma l med ian diastema is thus p roduced, wh ich has been termed the ' ugly duckling' (Broad bent, 194 1).

A year or so later, the lat eral incisors will ha ve de scen de d along the distal side of the central inciso r roots, to release their 'hold' on the na rrowed in ter-a pical w idth o f the central incisor roo ts, allowing the roo ts to d rift apa rt. The lateral incisors continue to move in feriorly along their eruptive path, progressively reducing their constricting influence on the cent ral incisor roots u nti l they reach the distal side of the nec ks of the central incisor crowns. At th is po int , their p resence and continue d downward migration serves to provid e a

mesially d irec ted force to the crowns of these teeth, moving them towards one another and partially closing off the median diastema. The long axes of the cent ral incisor teeth will also have cha nged, wit h the roo ts becoming mo re para llel. The lateral incisor long axes, however, are relatively flared in the coro nal d irection, wi th th eir root apices close to those o f the cen tral incis ors. A peri a pical view of th e area at this tim e will show the uneru pted permane nt can ine crowns, of eac h s ide, poi nt ing mesiall y toward s the lateral incisor apical area. They appea r to be the contai ning infl uence that causes the a p ical convergence of the incisor roots and th e reason th at the med ian diastema has not completely closed. Subsequent follow -up radiographs of the area w ill show the permanent can ine alte ring its relati on sh ip as it moves d ownward s along the distal s ide of the roo t o f the late ral incisor, uprighting the long axis of that tooth . Th e canine's ow n long ax is beco mes mo re vertical as it p rog resses an d as the root of the d eciduous can ine be com es resorbed. W ith the sheddi ng of the deciduou s canine, it finally eru p ts wit h a sligh t mesial inclination, ta king u p its p lace in the arch by moving the crow ns of the incisors towards the mid line, to close off the d iastema completely (Becker, 1978). As all th is occurs, the long axes of the incisor teeth change from be ing apically convergent to become more parallel and even slightly divergent. Th roug hou t the period of its downwa rd p rog ress, the pe rma ne nt canine is conspicu ous ly palpab le on the buccal side of the alveolar rid ge, from as early as 2 or 3 yea rs prior to its norm al eruption, w hich no rmally occurs at the age of 11- 13 years.

Theories regarding the causes of palatal disp lacement Long path of eruption

Fro m the early da ys of Broad ben t, in the 19405, the most com mon reason g iven for palat al d isplacemen t of the pe rmanent ma xil-

89

PALATALLY IMPACTED CAN INES

lary canine was the fact tha t it ha d a long an d tortu ous erup tion path, beg inn ing close to the floor of the or bit. It was cons idered that this tooth had m uch fu rther to travel before it erupted into the mouth an d that it ther efore had a greater chance of ' losing its way'. This has been stand ard teac hing for many years. Crowd ing

H itchi n (1956) considered that crowding of the dentition was the reason for this condition , althou gh he offered no evidence to su ppo rt his con ten tion. In general, crowdi ng o f the d entition results in the exaggerated d ispl acement of a tooth from its d evelopmental po sition in the arch. Th e d evelopmental po sition of th e max illary lateral incisor is lingual to the line of the arch , as we have already described above. Thu s, when crowding affects the earl y m ixed dentition, there will be insufficient space for the lateral incisor to migrate labially between the root of the cen tral incisor and the dec iduou s canine tee th, which is th e manner in which it normally com es int o the dental arch. It therefore cont inues to develop downwards, bu t in a lingu al po sition, and er upts lingual to the adjacent tee th.

A pa rallel env ironment is created when a second d ecidu ous maxillary molar is extracted before its du e time, and the first per manent molar drifts mesially into the available space. Sim ilarly to the lateral incisor, the d eveloping second p remolar develops palata lly to the line of the arch, an d its con tinued develop ment and eru ptive path will be in an exaggerated pa latal d irection, in mu ch the same way . We have po inted out above that the normal eru ption path of the permanen t canine is buccal to the line of the arch, and we also kno w that the latera l inciso r and first premolar, the tee th immed iately ad jacent to the canine, erupt befor e the can ine. Thu s, in the presen ce o f crowding. th ere will be reduced spac e in th e arch in the can ine area, and the close proximity of th ese ad jacen t teeth will prevent the canine from moving into the arch . The vertical development o f the maxillary permanen t canine will therefore be accompanied by its buccal d isplacemen t, to give the typ ical picture seen in the class 1 cro wded case (Fig. 6.3). Whether the tooth eventually erupts or rema ins im pacted is irrelevant, altho ugh bu ccal im paction is most unusual. It is therefore qu ite clear that the cause of th is type of d isplacement o f the can ine is

Figu re 6.3 Bu( (all y displaced ma xilla ry ca nin es due 10 a crowded a rch.

=_=::c

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ~_=____=____=

9O

com pletely different from tha t invol ved w ith palatal displacement. The two conditions are different e ntities . They shou ld ne ver be confused, no r shou ld they be lumped toge the r to [a nn an experimenta l group fo r clin ical research, as if to offer a homoge neous sa m ple o f im pacted teeth . For the purposes of study, it is far more logical to com bine all palata lly displaced canines. w hethe r they ar e un erup4 ted or erupted, since they share a com mon aetiology, alth ough their clini cal p resentation Illay be d ifferent. In a se ries of more recent clin ical research studies, Jacoby (1983), Becker (19&1 ) and Brio e t .11 (1986 ) have pointed ou t that the likelihood of palatal displacement is much reduced where crowding is p resent. O n the contrary, they have shown it to be a far more prevalent occurrence w hen the re is e xcessi ve s pace in the denta l arch. Non-resorption of the root of the deciduous cani ne

Lappin (1951) cons ide red that it w as the failure of the root of the deciduous cani ne to resorb that ca us ed a pa lat al deflection of the eru ption pa th of the pe rman ent canine, lead ing to its im paction. He re, too, on e may d raw a parallel with ot her teeth. In cases where .1 second deciduous molar is over-retained, owing to the presence of a malposed tooth germ, one may often sec on the pe riapical or panoramic radi ograp h th at on e of the roots has totally reso rbed , w hile the second roo l is on ly p a rtially so. The lon g: spi cu le of unresorbcd root that may be prese nt re ta ins the too th against na tur al she d d ing, w hile the fu lly de ve loped and unerupted second premol a r is situa ted immedia tely be nea th the crovvn of the deci duous toot h; in the area pre viou sly occupied by the resorbed portion o f the roo ts. Fro m this ty pe of clinical evi de nce, w hich is seen so w idely and freq uently in practice, it is gene rally con sidered that the p resence and ad va ncing eruption of the permanent tooth provides the s tim u lus for the reso rption, and a po rtion of root dista nt from the unerupted permane n t too th may be unaffec ted by this p roce ss. O n the ba sis o f this, Lap pi n' s view

would appear to be ' pu tting the ca rt be for e the horse'. Nevertheless , and in su pport of his argu ment, subsequent st udies (Howa rd , 1967; Ericson a nd Kurol 1988c; Linda ue r e t al, 1992; Pow er and Short, 1993) ha ve shown the sponta neous e ruption o f p reviously im pa cted ca nines in many cases, followi ng the ext raction of deci duous can ine s. This will be d iscussed a t le ngth later in this chap te r, under the head in g 'Preventive treatme nt a nd its timi ng' . 4

Trauma

In a recent clin ical repor t Brin et al (1993b) have illu strated how trauma, which leads to a cessation in the develo pment of a la teral incisor roo t, may be associated w ith palatal ca nine im paction . They expl ain th is by assu ming that (a ) the tra um a tic e pisod e may ha ve caus ed movement of the lateral incisor, or (b ) by cond uc tion, movement of the une rupted ca nine itse lf, or (c) in terms of the guidan ce theo ry, this is due to the shortness of the la te ral incisor root, w hose de velop me nt ceased as the res ul t of the tr a u ma. A fu rthe r alt e rnative cou ld place the blame on the possible p resence of chronic irr ita tion or resid ual infection a round the a pe x of a nonvita l decid iou s can ine too th (Fig. 6.4), wh ich may equa lly ha ve p rod uced the dc fle.-. cted path o f e ru ption, as po in ted ou t by Fca rne and Lee (1988). The gu idance theory

Miller (1963) an d Bass (1967) reported tha t there a ppea red to be an u nusua lly high preva lence of cong en ita lly m issing late ral incisors associa ted wit h palatally im pacted can ine teeth. They theorized th a t, u nder these cir cumstances, the permane n t ca nine lacks the gu ida nce normally afforded by the di st al a spect of the late ral in ciso r roo t. As po inted out ea rlier, in relat ion to norma l d e velopment, the ca ni ne initially has a strong mesial developme ntal pa th, w hich alte rs ea rly on ,

PALATALLY IMPACTED CANINES

(.1)

91

(b)

Figure 6,4 (.1, b) PL'ri,lpicil1 views of twu impacted canines, each associ a ted w ith a non -vita l decid uous canine.

w ith the canine be ing guided d ownwards, apparently along the d istal aspect of the la teral incisor root. Thev concluded tha t, in the absence of this guid ing influence, the canine conti nu es in its initial mesial an d palatal path. Th e too th then becomes impacted in the palata l a rea, posterior to the cen tra l incisors, and fails to eru pt in its d ue time, if a t all. Miller's conce pt was founded on information glea ne d fro m the st udy of six such cases. He assumed that , since a peg-sh aped or ot he rw ise abnorm ally sma ll la tera l incisor dev elops it roo t of mo re or less norm allength, such a tooth wo ul d provide the requ ired guid a nce for the normal e ruption of its ad jacen t cani ne. He the refore ration alized that these anomalo us teeth could not be an ae tiologic factor in ca nine im pac tion. Follow ing the trea tmen t o f se ve ral h undred cases o f this ty pe by the p resent author, a d ifferent pa ttern of association seemed a ppa rent. Pala tal im paction of the ma xilla ry canine a p pea red to be intima tely bound up w ith the occurrence of anomalous la te ral incisors an d les s \v ith the congenitally missing tee th .

Fu rt he rmore, a ste reotype of the ma xillary im pacted canine patient could be offered (Fig . 6.5), in which the pa tie nt is frequently a 15-year-old female, w ith well-aligned and normally rela ted dental a rches, sligh t s pacing and no real malocclu sion. Ch aracteri stica lly, the tee th are s mall, the la te ral incisors pa rticu la rly so, the re may be miss ing tee th, d ental de ve lopme nt is la te a nd the p a tient's motivation for trea tme nt is lovv, A series of clinica l resear ch stud ies followed, in w hich a sa m ple of pa tients w ho were su ccessfu lly trea ted for a pal a tally J isplaced cani ne was s tu died. In the first study (Becke r ct al. 1981), a wi d e and hig hly s ign ifican t di scre pancy in the num be rs of no rmal, sma ll an d pe g-sh aped lateral incisors ad jacent to an a ffected ca n ine was found , compa red w ith the p ublished data for no rma l po p ulations. In the inte res ts of accuracy, a ra ndom study wa s la te r pe rformed by the same resea rch group (Brin et al, 1986) to qu an tify the va riou s types of la te ral incisors found within the general population of the sa me geographic a rea, while using the same defini-

92

_ _ _ _ __ _ __

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

----'---~__=_::..c____'___=___=___"__=__=~

Figure 6.5 Late developing d ...ntition show ing sp acing, small pt'g -

shaped la teral incisors, teeth of poo r ana tom ica l conto ur and m ino r Clas s I malocclusion.

tion a o f anomaly. In the general popu lat ion, 93'1" of all lateral incisor teeth were of normal sh ape and size, comp ared with only 52% in

the palatal canine samp le. In the random pop · u lation sa mple, missing lat eral incisors were found in a pproximately 1% of the cases, which contras ted ma rked ly w ith the 5.5% of th is anomaly among the' impacted ca nine cases, Of 5 times as freque ntl y.

These results d ea rly support the concept of Miller and of Bass rega rdi ng the pa rt played by th e lateral inc iso r as a guide in the normal erupti on of the perm an ent can ine . Without this gui dance, normal erup tion is com promised fivefo ld. Ho wever, Mille r's ration aliza tion regarding the positive role of anomalous lateral incisors appears very much misplaced. Sm all lateral incisors we re seen in only -1% o f the ra ndom sam p le. wh ile the palat al canine cases showed this anomaly to be 8 time s as frequen t (25%). Furthermo re, only 2°;', of the gen era l populati on had peg-sh ap ed incisors, while 17'1., (9 times the frequ en cy) were seen among the palatal cani ne cases. Similar resu lts have since bee n shown in con firmsto rv st udies th ai h ave exam ined We lsh (O liver et al, 1989) and west of Scotland (Mossey et al, 1994 ) samples. We re small or peg-shaped lateral incisors to ha ve p laye d a positive role of any sort, as outlined in the guidance theo ry, the n one would exp ect figu res lower than 5.5%. Their presen ce is show n here to offer mo re than merely a loss o f guid ance to the de veloping penna-

ne n t can ine. The fact that the y increase the ch ance for im paction to almost tw ice tha t of the missing lateral suggest s tha t an add itional, ob structive ro le is played by these teeth. In the first st udy (Becker et at 1981), a hypothes is was presen ted based on the fact that the an omalou s small and peg-shaped la teral inci so rs develop very much la ler than no rma l latera l incisors. While no figu res a re ava ilable for the extent o f this delay, it see ms clear from clinica l obs ervation that it may be as mu ch as 3 ye ars - and this for teeth wh ose calcification normally begi ns at age 10-12 mon ths! If we arc no w to rel ate this to the ' gu id ance theory of im pactio n', we may postula te tha t at the critical time that the perman en t can ine requires the gu id ance, the roo t of the an om alous lateral incisor is too rudimentari ly developed to p rovide it . Th us initi ally the situ ation is pa rallel to that see n in congenital lateral inc isor absence. The result is tha t the canine d eve lops me sially an d palat ally and usu ally in a downwards d irection, into the vertica l alveo lar pr ocess, w here i t p rocec ds towards the palatal pe riosteu m. Th is describe s the first stage of palat al d is placement. The p alatal perioste u m may then halt fu rther progress o f the tooth, o r it ma y alte r the eru ptio n path to a more ho rizont al di rection, across th e pa lat e. In eithe r inst ance, this may then be defined as a first -stage pal at al impaction.

93

PALATALLY IMPACTED CANINES

Alte rnatively, the palatal periosteum may gu ide the develop ing canine downwa rds. The alveolar process in the canine reg ion is v -shaped in cross-section, su ch th at, with continued vertical movemen t, the prog res· sively narrow ing alveolus will tend to gu ide the abe rrant canine in a buccal/labial di rection. These corrective movemen ts of the pala tally d ispl aced canine arc the characteristic featu re of what may be termed the first stage of palata l di sp lacement with secon d ary correctio n (Figs 6.6a-d ). In cases of conge nital absence of the lateral incisor, a canine that was not palpable bu ccally at any po int in its ea rlier d evelopment m ay often be seen to finally erup t more mesially than normal an d in the line of the arch. In the presence of an over-retained decid uou s latera l inciso r or canine only, the correct ive movemen ts of the canine lead to the initi ation of root reso rp tion . Following the shedd ing of the d eciduous tooth or tee th, the pe rmanent can ine may then eru p t into the line of the ar ch. If a late-develo ping lateral incisor is p rese nt, it w ill now lie directly in the pa th of the d isp laced canine. The physical p resence of the lateral incisor will b ring an abrupt stop to these cor rective movements, an d any fu rther vertical d evelopmen t of the canine may only then be on the palatal side of the dental arch, completing the second stage of palatal di splacement. In sum ma ry, therefore, the ' guid ance theory ' comp rises five clem en ts. 1

2

Normal I'rll pticm. It ado p ts Broad bent's original view that, given the time ly and norma l development of a lateral incisor, guid ance fo r the canine is provided and a buccal path of eruption is to be expe cted, with the tooth palpable ea rly on . First-stage impaction. It offer s an exp lanation fo r the loss of gu idance at a critical time in the nor mal deve lop ment of the permanent canine, wh ich leads to a defle ction o f the developmental pa th o f the too th, causing it to mo ve pa lata lly. This aenologtc facto r may be created by a congen itally m issing lateral incisor or by a la te-d eveloping. an oma lous lateral

incisor. In the event that no vertical movement of the canine into the alveo lar p rocess occu rs, the resu lt may be a ho rizontal palatal im paction.

3

4

S

First-stage impaction with St'collJary correction. It goes on to explain the cor rective influence of the ver tical alveolar p rocess, wh ich redi rects the canine on a mor e favourable path. This scenario may be d ifficult to d iagn ose accurately, and the clin ician mu st d ra w his or he r own conclusions from the fu rther progress of the im pacted tooth, wh ich may be palpable, low d own on the palatal side, before it finally erupts close to the line of the arch. The tooth may th en spontaneous ly move mo re b uccally, in the abse nce of a latera l incisor, to reach the occlusa l plane in a close-to-n ormal bucca-lingual positi on. Second-stage ill/paction. Self-correction is preven ted by the p resence of an anomalous and late-d evelopi ng later al inciso r, rcdcflectm g the tooth further palatally. Th is may be termed secon d-stage d isplacement, and is an actiologic factor tha t is not seen where the lateral inciso r is absen t.

Second-stage impactioll wi tll secondary correction. As we sha ll see later, in the d iscussion o f trea tment tim ing. extraction of a d ecid uous canine, or even the later al incisor itself, may often lead to spon taneou s eru ption of the im pacted too th.

Small, peg-shaped and mi ssing teeth arc mo re frequent findi ngs among females th an among males, in th e rat io of 2 : 1. Furthermore, the m axillary permanen t canine eru p ts ear lier in females, which could mean that ea rlier lateral inciso r gu idan ce will be necessar y for its norm al eruption. These facts provide the hypothes is with some support in explaining why palata l canines a re more frequent in females and why anoma lous lateral incisors are a mo re pow er ful causal agent tha n congen itally absent lateral incisors . It is qu ite clear th at hered ity plays an im portant role in this hypo thesis. The assumption is tha t the genetically dete rm ined factor s (small, peg-shaped , missing lateral incisors, etc. ) provid e an env ironmen t that

94

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

[a}

(b)

«j

(d )

Fig u re 6.6 (.:1-0:1) 5o.-ri.11 radiographs ~hd late ral inci"o r. (d) Thl' tw o tee th ha ve e ruph'd imd a rc su pe ri mposed on mit.' another. At clinical e xamination, bo th eru p ted callinl'S 1'\"E'n' fou nd to be on tilt' p.l l,]lal "idl.'.

95

PALATALLY IMPACTED CANI NES

leads to a loss of guid ance of the canine, its ab normal pa latal path and impaction . Hered ity

Given the strong he reditary influence in palatal canine d isplacement, there are those wh o believe th at th is is the p rindpal factor involved and d ismiss othe r relat ionships as secondary or as similarly linked hereditary facto rs. In other word s, the palatal can ine is another lin k in the chai n of genetically linked phenom en a . In a stu d y of th e families of ch ild ren affected by pa latally d ispl aced maxilla ry canines (Zilbe rm an et al, 1990), a search was ma de dillOn!; the paren ts an d the sibli ngs for the related an omalies to which we ha ve referred abo ve . The p revalence of sma ll, pegsh aped and missing lateral inciso rs, latedevelop ing dentitions and othe r missing tee th among these d ose relatives wa s very high, in ad d ition to palatally im pacted canines. Th is evid ence points to he red ity as the causa l agen t for these associa ted pheno mena. We have contended that the ir presen ce ere-

ates an enviro n ment favourable to the develo pmen t of palatally d isplaced canines, and , as wa s to be expected, this phe nomenon wa s fou nd to occu r in an unusu ally high p roportion of these cases. The view that these phenomen a are each genetically determined . inclu d ing the canine d ispla cement, and frequ en tly occu r togeth er {Bjerkli n et al. 1992; Peck et al, 199·1. 1995), is eq ua lly tenable, bu l wo u ld ap pe ar to be an oversimp lification . The fact thai the ext raction of ad jacen t decid uou s cani nes or anomalou s latera l inciso rs greatly imp roves the chan ces of canine eru plion would lead us to belie ve th at local factors cannot be ignored as exer ting a powerful influ en ce on the aetiology of (imine im pact ion . Peck ct al (1994) have s tud ied the rran spos ttion of maxillary pe rmanent can ine and first p remola r (Fig. 6.7), and have fou nd a strong hered itary influen ce in its ae tiology . Since this type of cond ition of the canines can not be con strued as deriving from gu ida nce fro m the lateral inciso r, and cannot be influenced in any way by the size, form o r timi ng of the development of that too th, this has been used

Figu re 6.7

M.n i1l.u y c,Ulil\O.· /fi~t premola r trans pos itio n. An example of hereditary primilry tooth germ displacement.

96

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

as

.1

mod el to refute the ' guid ance theory'.

However, there is no basis for comparing transposition w ith palatal displacement, rendering the comp arison invalid (Becker. 1995).

Other forms of maxillary canine positional anomaly do occu r from time to time. which are d ifficu lt to equate wit h the mo re u sua l pattern of palatal or bucca l disp lacement. Genetic factor s see m likely to be the govern· ing factors, in which the entire too th is

located in an abnormal position. In these cases, it seems that the original site or or ient ation of the anlage, from which the tooth de veloped. was abnormal. Thus we occasionally come across pa tients in who m there is ad equ ate s pace in the ar ch for the ideal erup· Hen and alig nment of the maxillary permanent canines, ye t these teet h erupt buccally ectop ic (Fig. 6.8). Additionally , the eruption occurs relatively high in the alveolus an d the too th has no me sio-d istal contact with its immediate ne ighbou rs. This rep resen ts an anomaly analogous to the can ine-first premolar trans pos ition cases (Peck et at 1993), although its exp ressi on is much milder.

It is clear that there is a particu lar gen etic factor that has p roduced these unusu al and very specific can ine loca tions (Fig. 6.9). This is quite d ifferent from the more frequent buccally placed canine, which is the product of cro wding, and its position is d ictated by the amount of sp ace available for it in the arch and by a d irect interp rox imal contact w ith the ad jacent tee th . We may prefer to define th is rare cond ition as primary too th-germ d isp lacemen t, in or der to d istingui sh it from other and more com mon fo rms of displacement, wh ich have an en vironmen tall y influenced aetiology. The vas t majority of palatally d isp laced can ines show the root ape x to be ideally placed , in the line of the arch (Becker, 1995). Experien ce shows th at extru sion and tipping of the crown into its pl ace in the ar ch is usu ally sufficient, with little or no roo t torque being requi red in most cases. Th is ind icates where the too th 'is com ing from', and it is reasonable to ass ume that local causes have been ins tru mental in its d eflected path of eruption .

COMPLICATIONS OF THE UNTREATED IMPACTED CANINE

.. "" " \.' r.

"\

'. '. -

'- -

-.

.~

,

'

Morb idity of the deciduous can ine

"

.

-

Figu re 6.8 Th c canine has developed in a n abnorma l loca tio n, represent ing another e xa mpl... of primary tooth genn displacement.

Early mor bidi ty of the deciduou s ca nine is common for tw o reasons. First, its roo t may become marked ly resorbed, crea ting considera ble mob ility and eventual she dd ing, withou t the possibility of replacem ent by the pe rman en t tooth. This crea tes a problem in terms of restoration, since the space is u sua lly too small for a satisfactory replacement either by the mispl aced permanent canine or by some form of artificial fixed brid ge pont ic or imp lan t. The seco nd reason that suc h a tooth may no t survive relates to its relatively high susccptibility to interproxima l (particu larly d istal) caries. In Israel, it is still co mmo n to sec a fairlv extens ive d istal cavitv in this too th at around the age of 11 or 12 onwards, which m ay have been deli berately left untreated by

PALATALLY IMPACTED CA N INES

(.)

(b)

Hgure 6.9

(a,b) Bilateral primary tooth germ displacement seen on pano ramic and lateral skull films. The condi tion is under genetic control .

a general p ractitioner who was u naware of the likelihood o r existence of impaction of its pe rmanen t successo r.

Cystic change Loss of vitality may occur very early on in the carious process, in the deciduous canine teeth owing to the narrowness of the hard structures of these teeth and the relatively large pul p. Necrosis of the pulp and per iap ical pathology may be asym ptoma tic. Und er these circu mstances, there may be a direct in terconn ection between the apical pa thology and the follicular sac sur rou nd ing the impacted canine. This may stim ula te an enlargement of the follicular sac, whi ch is clea rly SL'€n on a periapical rad iogr ap h. It ma y also undergo cys tic change, to produce a dentigero us cyst (Fig. 6.10). This may also occu r wit ho ut any relation to pa thosis of the d ecid uo us canine. In strictly rad iological term s, an enlarg ement o f the follicula r sac to beyond 2 or 3 m m is generally cons idered to represen t cysti c change . In ra re cases, these

Figure 6.10 A dentigerous cyst su rrounds the crow n of an impacted canine .

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH -.::.:::..::.:-.::.:==== = .:..=-.::.:.:..== = "-

98

cysts may expand at the expense of surrou nding maxillary hone and di splace the can ine h igher and high er in the max illa, as ha s bee n described in Cha pter 1. Alternatively, and rarely, the chron ic peri apical lesion on the decid uous canine may itse lf become cyst ic -.1 rad icu lar cyst - and its

subsequen t enlargemen t may displace the ad jacen t teeth. inclu d ing the palatal canine.

Crown resorption The reduced ename l ep ithe lium su rro unding the completed crown o f .1 tooth may degenerate wit h age, and its integrity may be lost.

This allows bon e and con nec tive tissu e to come into d irect con tact with the crown of the too th, and os teoclastic act ivity w ill lead to resorp tion of the enamel and {ts replacement by bo ne - a process kno wn as replacem ent resorption. Over a long peri od of time, repea ted radiogr aphs o f the too th will show the en am el becoming less and less cont rasting in densit y, h ighligh ting this bone -for-en amel su bstitution (Fig. 6. 11). Subsequent su rgica l exposu re of the crown o f this too th will show a pitted su rface, wh ich is d ifficu lt to sepa rate from the su rro unding hard and s parse soft tiss ues . This finding seems mort:' likely to occur in adult pa tients in whom the impaction has been left untreated ov er two or th ree deca des (Azaz and Sht eyer , 1978).

Resorption of the lateral incisor root

Fig ur l' 6.11 l'c napical view of maxillary incisor

female.

~how i n~

.l rl',l

in a 63-year-old

advanced rcscrpnon uf the cr owns uf

two im p.lel''ll caruncs . Th., ("Jlidlos uf bot h tedh Me alm ost completely absent. an d lhe kd h Me ve ry radiclucent, w ith po ur defin ition .

Little is known about the reasons for the resorpt ion of the roo ts o f deciduous tee th that leads to thei r eventual sh ed di ng and why this doc'S not normally occu r with the roo ts of permanent teeth . Nevertheless, the p ro ximity of the follicu lar S.1C of an u neru pted perma nent too th to the roo ts of its deciduous p red ecessor appears to be the trigger that initiates the p rocess o f roo t resorp tion, p roba b ly as the resu lt of pressu re. The continu ity of this reso rption p roct"ss is then maintained by the fu rther ad vance of the erupti on of the permane n t tooth, which moves into new area s va cated by the reso rbin g root. Unde r certain condit ions, however, the p resen ce of ,111 unerup ted perm anent can ine tooth may lead to the resorption o f the root of the adjacen t lateral (Fig. 6.12) or cent ral inci sor. Furt hermo re, an d in a man ner similar to that see n w ith d eciduous teet h. the progress of this undesirable phenome no n d epen ds on fur ther eruptive mov emen ts on the pa rt o f the imp acted tooth . If the impacted tooth is removed or its p ath redirected, the resorp tion p rocess usually ceases. In this context, it is perhaps pe rtine n t to comment that the maxillary canine, which is the onl y pe rmanen t tooth whose eru pt ion

99

PALATALLY IMPACTED CANINE S

may ca use resorption of the roo ts of neighbo uri ng tee th to a ny significan t degree, is also the only pe rm an ent too th that normally de velops in close rel ationship w ith the de veloping apical a reas of the roots of other pc rmancnt teeth. The premolar teeth d eve lop in a rest ricted area, encompassed by the roo ts of the decid uous molars and at a dista nce fro m other pe rmane nt tee th . Th e central incisors an d first molar s erupt before their ad jace nt neighbo u rs, and the la teral incisor is relat ed to the neck area of the crown of the central incisor. The can ine, howe ver , is closely rela ted to the roots of the adjacent la te ral incisor an d first premolar, whil e it is still fairly h igh in the max illa durin g mo st of its eruption period . Marked resorp tion of the lateral inci so r root is no t com mon and only a minority of im pacted can ines seem to be associated w ith

Figure 6.12

The im p.Ktl-.J c.mi ne cro.... n is surrounded by ... large denngcro us cy"t. ... nd there is "'SSlIcl.ltl-.J root rcsorpnon of both the decid u ou s ca nine (10 bl- l·X!"--'CIl-.J) an d the perma ne nt la teral incisor ( pa thologjcalj.

it (Ericson a nd Ku rol, 1987a,b, 1988a ). When it occu rs, however, its onse t ma y be ra pid and its conduct aggressive (Brin et al, 1993a ). An indelib le im pression is usually left on the opera tor who ha s to deal wi th this eventuality . Thus ea rly identification o f the presence of lat eral incisor root resorption is im portan t in orde r no t to d elay the com men cement of t reatment to a tim e w hen the su rv ival of a n im po rta nt ad jacent too th ma y be th rea tened . For this rea so n. w h ile extra-oral radi ogra ph ic vie ws of the im pacted tooth ma y offer the best means of loca ting its po siti on accu rately, a good pe riapical view shou ld alwa ys be tak en and studied, w ith th is po ssibility in mind. It shou ld be rem e m bered, howeve r, that on ly resorp tion of the ap ical or inte rp roximal surfaces of the roo t of the la te ral incisor w ill be visible on the pe riap ical radiograph . Given that the im pacted can ine is mo st frequ ently rela ted to the pala ta l sur face of the roo t of the incisor, it is clea r that man )' areas o f reso rption of this aspect of the roo t s urface will escape recogn ition, o fte n until they are in a fairly advanced s tage, usin g conventional radiogra p hy . The use of computed tomography (CT) is the on ly availab le method for d iscovering root resorp tion of the palatal o r buc cal aspects of the roo t of a too th (Eri cson and Kurol, 198Rb). Several stud ies h ave bee n cond uc ted to try to ide ntify those la te ral incisors tha t a rc mo st lia ble to be afflicted by roo t resorp tion. These have la rgely resea rched pa ramete rs concern ing the im pacted too th, su ch as the s ize of the follicular sac and cys tic chan ge, none of which ha ve sh ow n a ny corr ela tion with root resor ptio n. Earlier in th is chap te r, the actiologtcal link be tw een palat al ca nines and anoma lous lat e ra l incisors was di scu ssed. It was po in ted out that, in a sa m ple of pa tie nts wit h im pact ed ca nines. almost half of the adjacen t lat eral inciso rs we re a nomalous. Th e sa me g roup of resea rche rs (Brin et al, 1993a ) tes ted the occurrence of root resorption aga ins t the va rious categories o f la te ral incisor (no rmal, small and peg-shaped ), to see if an y one of them was more s usceptible tha n the others. A strong correlation of the occurrence of rcso rp -

100

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- -- - - -- - - - - - - - - - - - -- - tion with those pa tients whose latera l incisors were no rm al in size was fou nd. Wh ile resorption of the lateral inciso r root has been shown to occur in 12% of cases in the t D-n-year-old age group (Ericson and Kurol, 1987a), when it docs, it is far mo re common in a normally sized. lateral incisor tha n wi th a small or pegshaped late ra l incisor. When a norm ally sized latera l incisor is associated w ith an adja cen t palatally imp acted canine, the chances o f reso rp tion of its roo t arc 7 times greater tha n if the lateral incisor is s mall or peg-shaped!

DIAGNOS IS Unerup ted pe rma nent maxillary canines cause the patien t relatively few problems, unlike the imp acted man dibular third molar. A retained deciduous canine ma y have a relatively poor ap pea ran ce comp ared with a properly align ed pe rm an en t canine, but most patien ts do not seek treatme n t for the retained deciduou s can ine. The d isco very of palatal im paction is therefore us ua lly made by the general dentist, at the time of routine dental exa mination.

Inspection The maxillary pe rma nen t canine normally eru pts at a denta l age o f abou t 11 years. Its non-appearance at this age should invite clinical ins pection and radiographic investigation, espe cially if its an timere is present. The maxillary incisor teeth are no rmally flared laterally and spa ced until the age of 10 years, as d escribed ear lier . Shou ld this situation st ill be t ru e by 11 or 12 yea rs, the clinician sh ou ld be sus p icious, since this means that there is a detail missin g fro m the mecha nism that smoot hly transfers the ugly d uck ling s tage into th e final ad ult align men t. with interproximal incisor con tacts. Ind eed , a res ultant pe rsistent med ian diastema may be the factor th at brings the patien t to the office, unaware of the impacted canine. to request treatment.

It is un like ly that a m issing lateral inciso r or a frankly p eg-shaped incisor will be overloo ked. Nevertheless, care should be taken to examine the size and sha pe of exis ting lateral incisors. Central and latera l incisors whose crowns have mesio-dista l straight or slightly tapering sides and lack the classical proximal contou r are usually sma ll tee th and often develop late. Some of these ar e peg-sh aped, a condition defined by their widest mes io-d istal d imen sion bei ng at the CEJ. Furthermore, the disco ve ry of a latedeveloping de ntition and a dentitio n in which the re are missi ng tee th, oth er than the la teral incisors, sh ou ld also be trea ted with a deg ree of cau tion. All these factors have been lin ked with p alatally d isp laced canines, and this possibility shou ld be thoro ugh ly in ves tigated, both at the time wh en the phenomena are first not iced and in subsequent follow -up examina tions that h ave been sche d uled to oversee the s moo th changeo ver from the mixed to the perman en t den titions. Abnormally position ed and unerupted canines freq uently affect the positions of neighbou ring tee th, pa rticularl y lateral inciso rs. We have alread y pointed out th at the root of the canine is usually in the line of the arch, with the crown mesially displaced. in addition to its pal atal tilt. This brings it into close relati on with the pal atal side of the lateral incisor, often d isp lacin g its roo t lab ially. Clin ically. this will be identified by a lingu al tilt of the crown of the too th, sometimes into a crossb ill' relationsh ip .

Palp ation We hav e poin ted out in the pr evious chapter that, under conditions of normal devel opment, the tooth is p alp able bu ccally abov e the deci d uo us can ine for 2 or 3 years prior to its eru p tion. The bu ccal as pect of the alveo lus should be palpated above the attached gingiv a and up to the reflection of the oral mucosa. A wide convex contour of the bone is ind icative o f the canine, im mediately be neath. Care should be taken not to confuse this with the narrower profile of the root of the decidu-

PALAT A LLY IMPAC TED CAN INES

ou s canine. In the event that this con tour is concave, the palatal sid e of the alveolar process sh ould be palpated to see if there is a clue to its location there. The decid uou s canine sho uld always be tes ted for mobility. If this test is even mildly positive, it will suggest that the pe rmanent canine is fairly close to the desired er up tion path and that severe disp lacement is unl ikely. ln th is situ at ion, the un erupted canine may not be palp able on either sid e of the alveolar ridg e.

Radiog raphy As we sha ll see later in thi s chapter, to plan the strategy of mechanotherapy properly for a particular case and to obtain a pre treatment assess ment of the pe riodontal prognosis of the treated resu lt, it is esse nti al to know the exact positions of bo th the crown and the root ape x of the un erupted tooth. A single periapical rad iogr aph is essential to iden tify pathology, such as root resorptio n, obstruction and cystic change, bu t it should be sup plemented by other films that wil1 help to locate p recisely the un seen tooth. The use of a second periapical radi ogr aph in the parallax method has the ad van tage of simp licity of technique, and provides both the o rth odontist an d the surgeon with important infonnation regard ing positioning, although the p recise locations o f crown and apex a re d ifficu lt to comp ute from these pictu res. A true lateral view (as seen on the lateral cephalogram or on a tangentia l film ) paired with a vertex occlusal or po stero-anterior cepha lometric view Me technically more d ifficult to obtain, bu t w ill provide the requi red accu rate th ree-d imensional po sitional in formation of the unerupted too th in its sim plestto-und erstand form. A panora mic rad iograph, in its cent ral po rtio n, shows the inciso r region in the pos teroanter ior view, an d will ind icate a palatal di splacement as an overlap of the Impacted can ine with the roots of the incisors. Th is is by far the mos t popular method used tod ay. However, the canine /premolar/ mo la r areas

10 1

arc reco rd ed 0 0 the same film in the latera l (sagittal) plane and not in the ante ro-posterior pl ane, as the consequence of the rotation of the X-ray beam . Thu s the film ma y be mi slead ing in relation to the ca nine that is not mesially d isp laced.

TR EATMENT TIMING From the age of abo ut 9 or 10 yea rs, it is usually possible to pa lpa te a normally developing maxillary perm anent canine tooth on the buccal sid e of the alveolus, high above its deciduous predecesso r. The greater the d egree of crowdi ng, particular ly after the eruption of the first p rem ola r, the more buccal is the d isp lacem ent and the more palpable will the canine become, as its eruptive p rocess b ring s it fu rthe r and fu rther d ow n on that sid e of the arch. In the event that the tooth is no t pa lpable at this age, radi ogr aphs sho u ld be taken to assist in locati ng the tooth accu rately an d to secure othe r in formation regard ing the p resence, size, sha pe, position an d sta te of developm ent of indiv id ual u nerup ted teeth and any pathology . In a patient you nger than 9 yea rs, the radiog raphs will not usua lly show abnormality in the pos ition of the unerupted canine tee th, even if the canines arc no t palpable and even if they are destined subseq uently to become palatally d ispl aced . Many of these no n-p alpable can ines will finally e rup t in to good positions in the den tal arch, in their d ue time, provided that there is little or no mesial and pa latal di splacem ent of the crown of the uneru pted tooth. It ma y be argued that even canines wi th an in itial mild palatal displacement will achieve spontaneo us eru ption and alignment despite a first stage disp lacemen t, if they un de rgo second ary correction (see ' Gu id ance th eory of impaction' in the section on Aetiology). Other canines, however, will not eru p t, and their po sitions may worse n in time, as may be seen in follow-up rad iographs. If it were po ssible to distinguish between the two earl y enough, a line of preven tive tre atment m igh t be adv ised.

102

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

Preventive treatment and its timing

1

Usin g pa nora mic radi og ra phs of young pa tients in the m ixed den titi on , Lind au er et a\ (1992) were able, to a low degree of rel iability (78')\, ) on ly, to p red ict p alatal im paction on the basi s of can ine ove rlap of the root of the lateral incisor.

2 3 4

Extract ion as a means of prevention: dec iduous c anines

As we ind ica ted ea rlier in th is cha p te r, se vera l a ut ho rities (Ericson a nd Kurcl, 198Bc) prescribe the extrac tion o f the de ciduous cani ne teeth in an a tte m pt to encou rage th e permanent can ines to erup t. The y h ave recom me nded seeing the patient an d d iagnos ing the pa latal positioning befo re the age of 11 wars, and have show n tha t extraction pe rformed a t thi s time offe rs a good p rog no sis fo r the.natu ral e ru ption of the canine, w ith 78% o f the canines in thei r sa m ple erupting into a clinically corr ect po sition. Caution m us t be ad vised in interpreti ng these resu lts, how e ve r, since the au thors di d not study an untreated con trol group, and th us Me not in a po s ition to d eter mi ne jus t how many of these tee th wou ld h ave eru pted wit hout this preven tive treatment (Lindaue r c t a t 1992) (Figs 6.13 and 6.14). Fro m their studv. Ericson a nd Kurol con cluded that prognosis becomes less fa vourable as the pal at ally displaced canin e's medial overl ap o f the la te ral inciso r roo t in creases a nd as the angle between the long axis o f the ca nine and the mid- sagittal pla ne w idens. They also no ted tha t, if posi tiona l im provement of the ca ni ne was not evid ent wi th in 12 months of the extraction, it was un likelv that improvement w ou ld occu r. From this di scussion an d fro m some con siderable an ecdot al clinical experience, we ma y ass ume tha t, under certain circum sta nce..' S, the extraction of a maxilla ry deciduous ca ni ne ma y be a useful mea sure in the p re vention of ins id ious canine im paction . To ach ie ve max imum reliab ilit y, the follow ing con di tions sho uld be met before extraction is ad vised.

5

Th e d iagnosis o f pala tal di splace ment m us t be made as early as possib le. Th e pa tie nt must be in the 1D-13-yea r age range, p referab ly wi th a delayed d ental age . Ac cu rat e iden tifica tion of the po sition of the a pex should be made and confi rmed to be in the lin e of the arch. Medi al overla p of the une ru p ted cani ne cusp tip shou ld be less th an half-way across th e roo t of the lat eral incisor. on the pan ora mic view . The a ngulat ion of the long axis should be less than 55° to the mid-sagittal plan e.

The la tte r tw o ite ms on th is lis t represen t conditions th at, if no t fu lfilled, may still lead to spon taneous eruption and alignment, so that, w hile the cha nces a re reduced, extr action may still be worth consideri ng. G iven that there is no tr u ly reliable method of early de tect ion of a potential p ala ta l d isplacement (Linda uer et al, 1992), the claim tha t pre-emptive ex traction of the d ecid uou s canine ha s elicited the normal erup tion of the pe rma ne nt ca n ine mu st be viewed w ith so me rese rvat ion , on the bas is of the present sta te of our kn ow led ge. Clin ical experience would lea d u s to be e nco u rage d by th e proced ur e in many cases, bu t an accurate assessment of its efficacy has st ill to be de termined . Extraction as a means of prevention: first premolars

Within the minority g rou p o f patients w ith im pact ed ca ni nes w ho are cons idered to be e xtraction cases, usually be ca use of incisor cro wd ing, a Class II rela tion or bima xilJary protru sion, the ch oice of teeth for e xtraction usually devolves upon the first or second premolar tee th. Th e reasons for this particular choi ce a re bound up w ith the history of orthodontics itself. Th is offe rs mu ch potential be nefit to the d is placed canine, sin ce the p roximity of these teeth to the canine facilita tes the im med ia te provision of s pace close by. It also affords conside ra ble op portun ity for a spon ta neous im p rove ment in the canine position (Fig. 6.15), during the early levelling and align ing stages of the mecha nother a py.

PALATA LLY IMPACTED CAN INES

(.)

(b )

Figu re 6.13 (a) A cnse di agnosed from thi s panoramic vie w ,15 hav ing bila te ral pa lata l canine dis placement and re ferred for e xtre ction of the dec id uous canines. (b) A yea r late r, a repeat film sho ws gTl'a t im pro ve ment in the position of both canines, and norm aleruption of the ca nines is imm inent, despite th e fact that thl' decid uous canines had nu t been extracted .

Extract ion as a means of prevent ion: lateral inc isors

We have noted. above that many of the im p acted cases that we see are associated wi th ano ma lou s lateral incisors. At the end of the treatment p rocedu re, it is often necessary to alte r the shape o f these teeth by prosthetic

crowni ng. laminates or com posite bu ild -ups. in o rder 10 ma ke the m aestheti cally acceptab le, particula rly those that arc peg-shaped , We have pointed ou t earlier that palata l can ine cases ge ne rally have sp aced dentitions, com p rising s mall teet h, such that cro wd ing and the need for extractions in the overa ll tre atment is unu su al. Ne verth eless, if

104

- --

-

-

-

- --

-

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

-

-

-

-

-

----'----

(b )

Fig ure 6.14 (.1 ) A case of ea rly cro wd ing treated by e xtraction of four

deciduous canines, to relie ve cmwding a t age g yl'':u s. No h int o f impending pal atal displacement of the ca nine is discernible on th is panoramic film . (b) One yeilT 1,l\er, the incisors are al igne d and spaced . Extraction of th.. fou r de ciduous first m olars (the second st age of seria l cxtraclion) was a d vised . (c ) The panoramic view taken a yl' ar la ter reveals the max illa ry right canine in a p.:d.ltdlly di spla ced location, despi te ea rly extr,lelion of thl' ..k d d uous ca nin e. Treatment of this case may be seen in Fig. 6.35. (,)

extraction has to be mad e to trea t the overall

malocclusion in these cases, consideration should be given to the extraction of these malformed lateral incisors, as an alterna tive to the convention al but healthy and an atomically perfect first p remolars. We have described how the guid ance theory of eruption of the canine offers a

cogent argument of how palatal d isplacement of the canine may occur. In those cases described as a first-stage displacement, it was pointed out how the vertica l wall of the alveola r p roce ss on the pa latal side stee rs the ve rticall y and palatally di rected eru ption on a more bu ccal cou rse, to produce a secondary

correction . Th is continues u ntil the developing cani ne comes up agai ns t the root of a la tede veloping lateral inciso r, wh ich for ms a ba rrier to its fur the r p rog ress. A second sta ge im paction is thus cre a ted. Logically, the removal of this barrier should lea d to a natur al im p rove me nt in the po sition an d eruption status of the im p acted canin e the second-stage im paction w ith secondary correction. In pract ice, clinical experience shows this to be largely tru e (Fig. 6.16). Extraction of the la te ral inciso r is no t a suitab le procedure in most cases, bu t in those pa tients w here it is ind ica ted, tr ea tment time may o ften be ve ry short. Ho we ve r, a nor-

PALATALLY IMPACTED CANINES

mally sized canine ad jacent to a cen tral incisor may create a marred and un sa tisfactory appearance, particularly if the cen tral incisor has a poor profile (freque ntly seen in these cases). Furt hermore, by lining up the canine and first p rem olar in place of the latera l inciso r an d canine, a di screpancy betwee n up per and lower tooth sizes may comp romise the occlus ion. Orthodontic space opening

The p reventive measu res that we have des cribed up to this point ha ve involved the extraction of teeth ad jacen t to the impacted on ly, nam ely the deciduou s canine, the lateral inciso r or the first premolar, in the hop e that the impaction will resolve spontaneous ly. An alternative and sometimes su pplemen tary line of p reventive treatment involves the generous opening of space for the teeth, using orthodontic appliances. One of the primary

fun ctions of o rthodo ntic treatmen t p repa ra· tory to the treatmen t of impacted teeth, is the crea tion of space in the de ntal arches for the im pacted teeth. When this is d one, une ru pted teeth may o ften steadily improve their positions, as will be seen on repea t radiographs, and may often erupt without su rgical inte rvention (Fig. 6.17). This is clearly due to an altera tion in the relation of the canine crown to the roots of the incisors and a conco mitan t alter ation in the gui dance influence of these teeth. It p rovid es fu rther evidence to sup port the guidance theory of im paction.

Timing of mechanotherapy Most cases are not identified early enou gh to take ad van tage of these preventive steps, and will usually be seen for the first time by the orthodon tist only after the initial an d, by

(b) Fig ure 6.15 (a) The left side of a Class II di v ision 1 case w ith bila tera l maxillary pa lata l c.:mifl<,' im paction. The maxi lla ry d ecid u ou s canines, deci d uo us second mol ars a nd first premolars were extracted a nd an a ttachme n t placed o n ea ch o f thl' impacted canines. No a cti ve orthodontic treatment w as co m menced . (b ) The same s id e seen 14 wee ks la ter . Both canines and second premola rs have erupted spontaneously a nd to a s imilar degree. App lianre thera py wa s ini tia t~-d at this poin t.

'06

THE ORTHODONTIC TREATMENT OF IMPA CTED TEETH

-------------~~------=--------------

,.)

(b)

'<'

'd' Figure 6.16 (d,b ) A pala tall y impacte d rihht can ine is .1 Jjaa·nt 10 the pe g -sha ped right lateral incbv T. while th., opposite canine has erupted in place of th... am"l'nila lly absent la te ra l incisor. (c.d ) The periapical films used to diagnose the pa lata l position of the canine by pa rallax. At the time o f extraction, th., palata l posit ion of the can ine was confi rm ed clin ically. (e) Thl' cani nl' has e ru pted on the bu ccal '>ide.

PALATALLY IMPACTED CANINES

107

(.,

(b,

Ce'

Cd'

C"

(0

Cg'

Ch,

(i)

Fig u re 6.17 (J-c) A Class 11, division 2 case with cro w ding in th e maxillary arch an d

SI'\'l'1'l' Sp"Ct.' loss du e to "ilrly ,'x lraction in the man d ibul ar arch. (d) A panora mic view s hows a pa la ta lly displaced right ma xillary ca nint'. (I') A similar ra d iog ra ph ta ken followin g d istal movement of a ll four mola rs and space reo pen ing. No t,· Improved po siti on s an d prospec ts of all the u ne ru pt ed teeth, particu la rly the can in e. ( f~i) The fin al den ta l a lign m en t an d occlu sion.

108

_ _ _ _ _ _ __

_

then, mo re obvious d iagn osis has been made by the genera lis! or pa cdod ont ist. A coexist ing malocclusion has often been the reason for the pa tient req uesting trea tment, an d the im pacted tooth will h ave been d iscovered only as the result of the ort hodontist's rou tine clinical an d radi ographic exa minatio n. The pa tient is gene rally in the full pennanent den tition stage, with the exception o f the decid uo us canine o f the affected side . Sometimes, the remainder of the dentition is in a close....to-ideal alignmen t and inter-a rch relat ion, as has bee n poin ted ou t ea rlier, although a minor degree o f local tooth malalignment may often be seen. Th is generally includes a laterally flattene d or collap sed ar ch form (Fig. 0.18) and spclce loss in the immediate Mea, wi th sp ace opening m ore mes ially (Oli ve r et al, 1989). In on ly about 15% of the cases ( lacoby, 1983; Becker, 1984) is actual crowd ing presen t. The periapical rad iographs should be carefully scru tinized to di scov er any evide nce of resorp tion of the latera l incisor root s. Should this be S(.'C'n, orthodon tic treatmen t, des ign ed 10 rapid ly d eflect the developing canine aw ay from the incisor, should be undertaken as

Figurc b.18 A pre formed archwire blan k laid over the occlusal su rfan'S of the teeth closely ccn torms to the den tal arch, exCt.>pI: in the a rea of the im pacted canine . wh ich shows lateral Ilatt erung.

_

THEORTHODONTIC TREATMENT OF IMPACTED TEETH ::..:.....---=..::.c:.----'----=--------'--"--------=--='____''=____

soon as possible. If the resorpt ion is advanced, cons id eration should be g iven to extr action of the lateral incisor, in the relatively u nlik ely event that the case is an extraction case. For the most pa rt, however, th ere is ra rely any reason to hurry int o treatment simply because pa latal dis placement has bee n di agnosed . The patient mu st first be prepared for the treatm ent that is to be u nde rtak en, initially by explaining the natu re and ramifications of the problem, using the radiog raphs and plaster mod els as visu al aids. The principal fu nction of th is exercise is to overcome a complacency tha t most of these pa tien ts have, since thei r p roblem is one in which the facial appearance and oral function are rarely com prom ised. The aim is to insp ire motiva tion and the necessary fu ture cooperat ion. The dentition must then be protected aga ins t the incipient da nge rs that the placemen t of appliances is likely to gene ra te. The necessary measures include a high level of oral hygien e and the usc of appropriate fluorid ati ng procedu res, both at home and in the den tal office, as well as the tr eatment of any carious or periodontallesions . After a period. of a few wee ks, during which the pa tien t will, it is to be hoped, have undertaken these oral hygien e responsib ilities on a regular basis, an oral exam ination shou ld show p ink, firm and s tippled gu ms and an absen ce of plaque on the tee th . Th is bei ng so, the time w ill be ripe to begin or thod ontic treatmen t. In the non-coo pera tive pati ent, treatmen t sh ou ld be denied until the ab ove cond ition s arc fu lfilled , Shou ld the dental awa reness of the p atien t be too low for this ever to occur, altern ative tr eat ment mod alities sho uld be consi d ered, particu la rly prosth etic replacem ent, although, for these to be su ccessf u l in the long term they ma y be just as reliant on oral hygiene as is orthodont ic treatment. Neve rtheless, an operative d ecision may be delayed for quite a lon g time, in view of the relat ively low incid ence of morbid ity, provided th at p eriod ic rad iograph ic mon ito ring is pe rformed. Postponemen t for a few month s or ev en a yea r is rare ly a p roblem in straigh tfor ward orthodontic terms, and if it serves to b ring the

PALATALLY IMPACTED CAN INES

patien t roun d to the ways of proper home care then the time spent w ill h ave been wor thwhile. Un fortunately, as already mentioned, the d enta l development is often d elayed, which is why these patients reach the perm anen t d enti tion stage with the can ine impaction d iagnosis mad e onl y at the age of 14 or 15 years. Thus, from a social po int of view, the patient may be less inclined to wea r appliances if fu rther postpo nement is en tailed . Fro m the strictly developmental point of view, the best time for thera peu tic intervention is when the root of any affected too th is of a length that is seen at the time o f norm al erup tion . For the canine. th is is a little in excess of th ree-quarters of the po tenti al roo t length, wh ich is virtually always present by the time the di agn osis of palatal di splacement may be d etermined .

sen t con text, although we shall now be d ealing with the trea tment of the entire de ntition and no t mer ely the area imm ed iately ad jacen t to the impacted tooth. The p rincipl es, as they relate to the palatally d isp laced can ine case, need to be adapted to the new circumstances. and may therefore be p resen ted as follows. 1

2

GENERAL PRINCIPLES OF MECHANOTHERAPY When a patient arrives at the or thod on tist' s office and a palatally d isplaced an d un erupted canine is d iagn osed, treatment must be planned in a d isciplined manner. We have seen in Chap ter 5, in regar d to the im pacted m axillary centra l incisor, that orthodontic p reparati on of the case is requ ired and th at su rgical interve ntion is not to be undertaken in any haphaza rd or u nplanned manner . Applianc es that are to be used to dis impac t, erupt and align these teeth m ay also be used to align the other tee th, with very little mod ificatio n. For this reason, the local anomaly and the overa ll m alocclusion are usua lly dealt with together in one full and comprehensive orthodontic treatmen t plan. A diagnosis o f the overall ma locclusio n need s to be mad e and a problem list set out, which includes the palatal canine. The p roblem list is then rearranged into a treatment prio rity list, in wh ich alignment of the impacted canine sh ould preced e many of the other items to be treated. The same p rinciples tha t were u sed in the planning of treatment in Chapter 5 are equally app licab le in the p re-

3

4

5

The app liance sho uld have the capabili ty to kr.>el ami rotate all the tee th in the sa me jaw rapid ly, and, with controlled crown and roo t movemen ts, to open adequate space to accomod atc the impacted tooth. As we sa w when dealing with imp acted incisors, this spa ce is required bo th at the occlusal level and between the roots of the adjacent teeth for their en tire length. This stage requ ires the use of fine levelling and align ing archwires. With the initial align ment achieved an d no furt her movement of individ ual erupted teeth need ed, these tee th are transform ed into a composite and rigid anchorage Ill/it, in wh ich each of the teeth p lays an integral par t. This is done by substitu ting the flexible ar ch wires with a heavier wire, whose ga uge is as large as the bracket w ill take, in or de r to allow as little ' play' o f wire w ith in the bracket as po ssible, thereby maximizing the anchorage value of each tooth. The surgical expos ure of the cro wn of the im pacted tooth sho u ld be performed in a manner that will achieve a good pe riodontal prognosis of the treated resu lt. An attachment is bonded to it and the fl ap fu lly closed, with only a fine ligature wire lead ing th rough the g ingival tissue to the re-covered tooth . Using an au xiliary mea ns o f traction from the now rigid orthodon tic ap plian ce, a gentle and continuous light force, with a wide range of activity, is ap plied to the tooth, and is aime d at erupting the impacted tooth along a path that is free of obst ruction from neighbouring teeth (Becker and Zilberman, 1975, 1978; Jacoby, 1979; Korn hause r ct al, 1996). Th ere shou ld be filial ddai/illg o f the po sition of the form erly impacted tooth,

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

110

together w ith that of
tion will usually be reduced at this point. However, it may sometimes be treated ea rlier in the firs t of these st ages and before surgery is con tem plated, for exampic when early ort hopaedic treat ment is to be und ert aken wit h the us e of a functional or en-b loc headgear appliance, In the mixed den tition stage. The re art.' essentially four ways in wh ich space may be provided for the palatally displaced canine.

Existing incisor spaci"g //lay be closed off by moving the lateral incisor mes ially. Inciso r spacing is due to the failure of completion of the ugly duc kling stage of development (Broadbent. 19~1i Becker, 1978). It was pointed out at the beginning of this cha pter that the final stage in anterior space clos ure occu rs when th e canine erupts and influences the lat eral

2

inciso r to move mesiall y . It was also poin ted ou t th at these impacted teet h are in tima tely linked wi th small and pegsh aped lateral incisors an d w ith small teeth in ge neral. Th is be ing so, it is common to find anterio r s pacing in these patients (Fig. 6.19). tmprooing archform. Whe n the maxillary pe rm anen t canine eru pts norma lly, it d oes so along a mo re bucca l pa th th an the deci d uo us canine and slightly buccal to the lateral incisor and first premolar, earning the tooth the title of ' corn ers tone of the arch'. Co mparing the two sides of the maxillary arc h in a unilaterally affec ted patient, we have already pointed out that, in the canine areas, there is a much na rrower maxillary width on the side of the deciduous canine th an on the nor ma l side. Exploiting the improvement in this archfonn, prod uced by an orthod on tic applia nce, will add two or three millime tres o f space for the d isplaced toot h (Fig. 6.20).

"j

(b}

(oj

(Jj

[e )

(f)

Figu re 6.19

(01-<) In.1
111

PALATALLY IMPACTED CANINES

(b)

Fig\lre 6.20 (a, b) Impro ving the .uchform bas provid ed a dequa te s pace.

3

4

Increasing arch length. If crowding is mild , the use o f a headgear is recommend ed in or der to move the maxillary mo lars d istally. Th is will provide the extra space fu rther forwa rd, wh ich may then be concen trated in the canine area, using a mu ltibra ckcted appliance sys tem (Fig. 6.21). Trea tment is beg un with fine levelling ar chw ires, un til the ind ivid ual tooth heights, bucco-lingual pos itional d iscrepancies and rotat ions have bee n correcte d, an d uprightin g has been achieved as necessary. Extraction of teeth When crow d ing is mo re seve re, part icular ly wh ere there is also a Class II d ent al relation that is to be treate d wit h the use of in ter maxi11 ary clas tics, the extraction o f a premolar too th on each side of the den tal arch in the ma xilla and, usu ally, in the mandible will be requ ired, With the extrac tion o f the p remo lar, space for the im pacted can ine is imm ed iately and ver y locally ava ilable, and so app liance thera py is no t nee ded to p rov ide the space. Secon dly, following the loss of the first p remolars, align men t, levelling and rotation of the remaining teeth are very much sim plified. Thirdly , with a local an aesthetic already covering

the area and a su rgi cal wo und inev itable, it is logical to ext ract the deci duous cani ne and expose the im pacted canine at the same time, to red uce the numbe r of su rgi cal intervention s and post-su rgical di scomfor t to a min imum. Thus, in extraction cases, it may be reco m mended that the surgical exposu re be un d er taken p rior to the p lacemen t of an app liance (see Fig. 6.15). The achievemen t o f good arch form is an im portan t initia l goal in the maxilla ry arc h in non-extracti on cases. After the initi al levelling wires, a coil sp ring is placed on a more substantial archwlrc of ide alized form, to increase the canine space by mov ing the latera l inciso r mesially and the first premolar d istally, u ntil interproximal contacts are establ ished elsewhe re in the ma xillary arch. Th is will usu ally p rovide more than enough space for the u neru p ted can ine. A heavier-gau ge archwlrc is now firmly ligated in to the maxillary appliance, and the space for the canine m ust he retained. In the va rious edgewise and p rescrip tion pretorqued bracket tech niq ues, as heavy a rectangular ba se arch as poss ible should be used. In th e Bcgg and Tip-Edge techn iq ues, a round

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

~:..=~==:.::...:.=====.:::.:.:::..:=:c

112

(.)

(b)

Figu r e &.21

(a) An extra-oral hea dgear is being used to move the mo lars di stally. The tied-in li~l pala tal arch will be removed and us•.,..d later for verti cal traction Whl'fl th e cani nes a re exposed. (b) Aft.. r the premolars have been moved distally, mo nthan-adequa te space has been prepared for the unerupted canines, sc...' Il hen' atthe time of their cxpc...urc.

0.020" or 0.022" wire respectively shou ld be used as the base arch, wit h the addition o f upn gh ttng spri ngs o r torquemg auxilliaries to act as ' br akes', if nec essary.

The space that has been reopened for the canine ma y be maintaine d u sin g the same coil sp ring. which will l1L"Cd to be deactiva ted . However , it is d ifficu lt to ad just the sp ring to ma intain a s pa ce accura tely, and one w ill usually find that the space will increa se or decrease sligh tly over the succee ding mon ths . Furth ermore, a coil spring qu ickly fills with food particles ond is im possible to clean effectively . A mu ch better alternative involves u sing a meas ured and slightly curved length of s tain less steel tu bing, which is threaded on the archw lre and is tied o r p inned betwee n the b rackets of the premolar and lateral incisor, in p lace of the coil s prin g. This adds a great d eal of rig id ity to the archwire in the area o f g reates t impor tance, and hel ps in res isting d is tortion, thereby p roviding an excellent and firm base fro m wh ich to apply force to the im pac ted canine. Many of these canin es have to be moved over a long d is-

tance to bring them in to the arch, and several will req ui re root movemen t of the d iffere nt types before the y may be p roperly b rou gh t into position and the case comp leted . This inevitably expe nd s ancho rage. The me asures and p reca u tions that we have d escribed will contribute much to preserving the anchorage.

THE NEED FOR CLASSIFICATION OF THE PALATA L CA NINE Dur ing the orthodont ic trea tmen t of a patien t, as with any other prescribe d form of med ical or de ntal treatmen t, at tention is p aid to achieving the maxi mum benefit that the appr oa ch has to offer, while su sta in ing the minim u m possible adverse cha nges in the health of the de ntition and its suppor ting tissues that may be caused by the treatment. To this end, the orthodontist mus t ensure an adequate level of o ral hyg iene before and d uring th e period when the proced u res arc perfor med . The forces ge ne rated by the ap pli-

PALA TALLY IMPACTED CA NINES

ances mu st be wit h in certa in lim its, com pa tible w ith physiolog ical toot h movement, so that perma nent and irrever sible d amage is not in flicted on the den tition . In an extrac tion case, the decision rega rding wh ich teeth to extract is usua lly mad e on strictly strategic criteria, insofar as certain tee th require to be brou ght to particu lar places, an d appropri ate an chor teeth need to be chos en in or d er to ach ieve this. Given a good prognosis o f each of the tee th in the mou th, with no se verely carious teeth and excellent peri od ontal health, the criteria of orthodontic treat men t strategy are the guiding criteria behin d th is ext raction decision. However, when a tooth or teeth are present wh ose long -term p rognosis is in doubt, such as a mo lar tooth that is in need of root canal treatment and a pos t-and-crown restoration, th is becomes an ad diti onal factor th at mu st influence the choice o f tooth for extraction. It would not m ake long-term sense if the im mediate an d beau tiful ort hod ontic resu lts we re to be based on tee th th at would not be presen t in the mout h a few years later, whi le hea lthy teeth o f excellent prognosis had been sacrificed in the name o f strategic convenience. Maxillary canine impaction in a case where teeth requi re to be extracted as part of the overall or thod ontic treatment p resents a simi lar d ilemm a. The can ine ha s a longer roo t and con tributes mu ch to the pati ent's ap pea rance, par ticularly the smile, which makes it a very valuable tooth and one worth the expend iture of considerable effort to brin g it into pos ition . Its substitution by a first premo lar is not usually des irable. It is inappropriate to auto matically and blind ly extract an impacted can ine w ith a good prognosis, in preference to an erupted first p remol ar, just as it is ina pprop riate to ext ract a first mo lar rather than a first premolar sim p ly becau se th e molar has a sma ll occlusal am algam filling. But what if the long-term p rognosis of the can ine is poor, as the consequence of its h aving been thro ugh the proces!'>es of surg ical expos ure and orthodo ntic alignmen t, over the period of m any months or years th at we rt' spent in its meticulou s alignment? Pe rhaps it wou ld ha ve been better to remove that pa rticular can ine at the

ou tset and 10 have bro ug h t the first premola r to its place. Extra ction cases arc very much in the m inority among patients with pa latall y impacted canines (jacoby, 1983; Becker, 19s.!), and so, for the most pa rt, every effort mu st be mad e to bring the can ine into the a rch and to do th is in a manner that will provide it with its best possible pe riodontal prognosis (Free man, 199-J). The clinician mu st caref u lly assess each ind ividual case, to be in the pos ition in which an accurate app raisal of the seve ral as pects where progn osis of the results of the treatment is at stake , prior to the beg inning of tre atmen t. With th is information, the op timal decision regard ing extraction may th en valid lv be made. At the time that the patie nt 's record s arc being stu di ed in order to formulate a su itable treatment p lan, it wou ld be helpful if there we re a way in wh ich it is poss ible to assess the long-term p rognosis of an impacted canine before treatment is started. It is therefore cruc ial to seek a key that may be available to help us to decide wh ich canines will be ad versely affected in period on tal terms: (a) by surgical access to them, (b) by the relative difficulty in orthodontically mov ing them into align ment. From the surgical as pec t, which we h ave d iscus sed in Cha p ter 3, mini mal ex posu re and full flap closu re (with attend an t atta chmen t bonding) is the preferred line of trea tment, aimed at prima ry healing. Docs a tooth thai requires a whole range of d ifferent types of orthodontic movemen t pay a periodontic penalty, in the final analysis, in com parison w ith one that is more simply aligned ? Teeth that are mech an ically erupted br ing with them a gen ero us amount of alveolar bon e. It has been shown in stud ies in Israel (Becker ct al, 1983; Kohavi ct al. 1984a,b) that the assisted erupti on of buried tee th with the use of o rthodontic ap pliances prod uces a collar of alveolar bone arou nd the eru p ted tooth tha t is g reater than tha t seen on normally eru p ted adja cen t teeth. These stud ies have shown this to be true on ly wher e surgical

114

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

-------------'-~--'-'-'-----'-----='--------'---'----'-~"--=--~xpos urt!

was conservative and did no t involve the removal o f the ent ire follicula r sac. Radical surgery leads to less bone support tha n is present in a norm ally erupted too th, a nd considerably less tha n the m in imally exposed impacted tooth. The most likely exp lana tion for this is be found in the proced u re that prosthod ontists call ' fo rced eruption' (Ingber, 1974; Stem and Becker , 1980). When one side of a tooth is frac tured or destroyed by ca ries to below the heigh t of the cr estal bone, an inf ra-bony pocket is p rodu ced . The treatment thai is prescribed to eliminate this is to mechanically erupt the tooth away from the bo ne margin a nd to thus o rthodonticallv reverse the rel ationship between preparedcrown shoulder or cavity margin and the interproximal alveolar bone. At the same time, the other sides of the same tooth, whose relationship with the bo ne was normal to begin with, are ext ruded toge the r w ith their ad jacent alveolar bo ne . Thi s genera tes e xcess ive bone in the latter areas, extend ing more coro nally th an is normallv seen, which sometimes needs to be redu'u >d by periodontal / periosteal surgery. It has been shown by Ingbe r (1974) a nd by Stern and Becker (1980) that , in contrast with extrusive move ment, tee th tha t u ndergo roo t uprig ht ing and torqu eing movemen ts end u p w ith a s igni fica ntly lowe r crestal bone level than un trea ted controls, and the histogra m in Fig. 6.22 shows the in fluence of the various combinations of conse rva tive-ve rs us -radical su rgical exposure and extrusion ! tippingversus- root mo vement orthod ontic forces on the rel a tive bon e su pport of these teeth. Th ese resu lts arc an ind ication of the periodont al prognosis of the teeth con cerned . O ne last factor, which is often ignored or sim ply ove rlooked , relates to roo t resor pti on that ma y occu r in the im pacted tooth during the exte nde d period of time th at may often be inv olved in its alig nm ent. In orthodontic trea tme nt, generally. res orption of the roo t ap ices of teeth may so me times be seen . The rea sons for th is occurrence a re no t d ear, althou gh recent e vid ence has linked thvroid hormone wi th the phen omenon (Lobergand Engstrom, 1994; Pou m pa ros et al, 1994). Nevertheless, there is no kno w n key that may be used to

Pe rcentage

" " "

~

94

po

90

.86

-

-

-

" Figure &. 22

Bone support tcve ls in the treated canines (light ba rs) compa red with rbe norrn ,lIly erupted o pposite canines (da rk ba r); X. minima l su rgl.'ry and p rima ry closure; X.. su rgl.'l)· in w him th., follicula r sac was removed d o w n 10 the eEJ; ~.. o rthodontic tipping. extrusion a nd rotati on movement s only; 1\.1.. roo t u p rig hting a nd tor qu ein g movement s. (Adapt ed from Kohavi et al, 1984b.)

p red ict in which patients resorption will occur. Wha l is found, however, is that the resorption process almost inva riably stops w he n orthodon tie too th movement is completed. In most pa tie nts for whom ma jor orthodontic movemen ts ha ve been ca rr ied ou t, resorption is exce pti ona lly small a nd o f no clin ical sign ificance. Neverthe less, the re a rc occa siona l cases whe re these ill effects may accou nt for the loss of 3 or 4 m m of the original root length. It als o a ppears th at treat ment time has little im p act on root resorptio n, even when treatmen t has lasted for 6 years (Beck a nd H a rris, 1994)! In the absence of defin itive in forma tion regar ding the mecha nisms in vol ved, howeve r, it would seem w ise tha t, for those pa tients w ho a rc p rone to roo t resorptio n, or thodontic trea tmen t shou ld be kept to a minim u m, bo th in ter ms of du rat ion a nd s imp licity. Th e optimal res ult for th at pa rticula r patien t may not e ven come close to the id eal. For the resorption-s usceptible case, it cou ld conceivably ha p pe n tha t all the p reca u tions that we ha ve de scribed may be followed scru pu lously and a good pe riod ontal resul t

PALATALLY IMPACTED CANINES

m ay be ob tained. However, unusually severe resorption may accou nt for a final root length of, say, 12 01 01 . The same 2 01 01 d ifference in height betwee n crcs ral bone and CEJ will give a relative bone support in thi s pa tien t of on ly 83% an d the long-term prognosis mus t be jud ged accordingly. Th us for cases in wh ich there is a more compromised bone loss in the cervical area, with a g rea ter CEHo-cresta lbone height d ifference, the relative impo rtance of root resorp tio n as a facto r in long -term tooth survival increases. Mon itoring for early ind ications of root resorption may be performed during the progress of the mechanothe rap y of a given Impacted canine, using peri apical radio-graphs. However, since the pos ition of the tooth is changing d uring the procedure, com parison with earlier films may be d ifficult. It should also be remembered that, even when marked resorption is noticed , it is un likely that the or thod ontic treatment will be stopped much befo re full eruption h as been accom plished . Less wou ld render the canine va lueless for all p ractical p urposes and under anv circumstances. The efficacy of radi ogr aph ic monitoring is only relevant a t the point whe n the crown of the tooth has been bro ugh t into its place in the arch and a decision has to be made whether root upright ing and torquetng movemen ts ar e d esirable. If a periap ical radiogra ph taken at this ju ncture sho ws that significant resorption is evident, its severity must be offset against the relative importance of producing these roo t mo vemen ts.

dictate the qua lity of the su pporting structures of the treated result. Accordingly, it becomes clear that the pa tient's best interests are served if an accu rate visu alization of the exact location of the buried tooth is made at the ou tset, at the time of treatmen t plann ing. It follows tha t if palatal canines arc class ified in relation to their pos ition in the maxilla then they will esse ntially be grou ped in accordance with the prognosis of their therapeutic outcome. The classifica tion tha t is offered here is based on two va riables: (a) the tran sverse relat ion ship of the cro wn of the tooth to the line of the dental ar ch, wh ich may be close or distant (nearer the midline); (b) the height of th e cro wn of the tooth in relati on to the occlusal plane, wh ich may be defined as h igh or low . Dete rmination of the location of the crown of the impacted tooth is achieved by emp loying th e rad iogra ph ic methods that we ha ve ou tlined ea rlier. This po sitiona l determination may be su bsequen tly confirmed by d irect vision at the tim e o f su rgical expos ure. In th is section, several cases w ill be presented to illustra te the salien t clinical featu res of the impacted canines in each of the classificat ion gro up s. An approach to treatmen t will be d iscussed w ith in each g roup, and how th is nee ds to be ad apted to su it the cond itions seen in each. Where re levant, cases that were treated inap pro priately will also be p resented, with the aim of reve aling how the sho rtcomings of the results occur red and to d iscus s wha t alternatives cou ld have been employed to prevent the und esired sequelae .

A CLASSIFICATION OF PALATAL LY IMPACTED CANINES We have concluded that (a) surgical traum a is grea ter when access is diff icult , an d (b) or tho don tic alignment is mor e comp lex whe n the impacted tooth has a greater dis pla cemen t. pa rticularl y if the root apex is not in the line of the a rch. Yet it is these two factors, both of whi ch relate to the po sition of the tooth, th at w ill later

Group 1 • Proximity to line of a rch: close • Position in maxilla: low Typica lly, pa latal canin es that arc close to the line of the arch and low in the maxilla su ggest a good prognosis, insofar as the too th is usually palpable in the palate and read ily accessible to su rgery (Fig. 6.23). In its simp lest fonn, the

116 _

_

_

_

_

_

_

_

_

_

_

ORTHODONTIC TREATMENT OF IMPACTED TEETH _ THE "-'------'--_ _"-'---.c-.--:..-----'---'--_

(. j

(b )

«)

(dj

(e)

(I)

Figure 1>.23 (a.b) Int ra-o ra l \Iil'w~ of the initial conditio n . (c) Space was "pcncd usin g .\ coil s pr ing ,lIld slidi ng mecha nics. An oversited stilin1css s t<.'Cl tube is c u i to measu re, cu rved and pl,lc('d un tlw ar ch wirc to maintain s pace and to increase base arch rigidi ty. (d) EXpOSUTl' and ,1 tl,lch mcn l bonding. Th e pi glilil ligature is d raw n dow nwa rd an d Lo ha ped ove r the a rchw trc to allow for rvapproximotion of flap w ithout impingement. Traction W ,15 applied immed ia tely. (e) Tw o wl'Cks posl -surgl'ry, .1 new 'slingsh" t' d ,lst ic module is stretched bet ween the bra ckets of the [.l ll'r.,l incisor and first premo lar. Its middle po rti,'" is r,I;.......l to ~'ng,' ge the pigtail hook w ith il cont rolled a nd meas urable light extru sive force. (f,g) Three mo nths P'I'st-surgl.'ry . An inferior ly a nd la te rally of~t light w ire arc h is substituted, and the tooth liga ted w ith s teel ligatu .... w irl' to .lchil'\"~· fullnuption . An or thodon tic bra cket no w rep laces the eyelet. (h,i) The gingiva l appea rance shows compa rable gingivallevels o n the treated versus the un treat ed side. (j.k) Periapi ca l view, showing comparable supporting bone levels in the treat ed and untreat ed cani nes.

PALA TAll Y IMPACTED CAN INES

(fi gure b.D continued )

'. (h)

(i)

canine is op posi te the space and is no t rotated . The root apex is usually in its correct locat ion and root movements are rarel y necessary. Surgery

A pproac hed from the occluso-buccal (Fig. 6.23d), little bone removal is needed to rea ch the canine . Alte rnatively, following the reflection of a palatal flap, the canine is im med iately obvious under its bu lging bu t thin covering of bone, on the inner su rface of the alveolar ridge. Minimal removal of eggshellth in bone is needed to reach the follicular sac,

(k )

and access for bonding an attachm ent to the tooth is good. Aft er resuturing of the full flap, th e p igt ai l ligatu re is drawn throu gh the sutured ed ge in th e direction of the ma in archwl re. Planning the orthodo ntic strategy

With the too th immed iately opposite its place in the arch, o rthodont ic al ignm ent req uires some extrusion, bu t principally a bu cca l tipping movement. Thus direct force application bet ween pigtail and archwire is the most appropriate (Fig. 6.23e).

116

THEORTHODONTIC TREATMENT OF IMPACTED TEETH

Problems that may b e encountered

In the simples t group 1 case, the eye let may often be sufficient to complete aU the movements req ui red. Alt e rn atively, an d if surgery has exposed a su fficiently long clinical cro w n,

a conventiona l brac ket may be placed immed ia tely. However, it should be remembered that, L; the too th moves buccally, it gathe-s gingival tissue ahead of i t, an d, if ora l hygiene is not excelle nt, the ex ubera nt so ft tissue w ill become infla med an d may im pi nge on the b racket. Undoubtedly, wi der exp osu re o f the crown w ill elimina te th is, bu t w ill compromise the periodontal tissues in th e final a nalysis. Thus it is w iser to use an eyele t initially.

Complicat ions

Group 1 can ines, in their initial po sition s, ma y be com pl icated by rotation, m esial crown d isp lace men t or pa la tal root d isplaceme nt. (a) Rotation. The type of rota tion tha t the ca nine ge nerally p resents is a mes lo-Hng ue l rotat ion, wit h the bu ccal s urface of the too th facin g mesially, toward s the root of the la te ral incisor. Th is mean s tha t, during trea tm ent, the appliance must incorpora te a rotational mec hanism to bring the too th into align men t. The simp lest manner in wh ich to do th is is to in itially place the eyelet on the a na tom ic lab ial surface of the crown of the can ine, which faces anteriorly, towards the la teral incisor. The ' slingshot' elastic is placed o r ela stic th read tied be tween the eye let and the cu t length of stainl ess stee l tube (Fig. 6.23c) tha t has been thr eaded on to the ma in archwi rc, for use as the canine space m aintainer and to ad d rig id ity to the ba se arch. While the canine is being mo ved towards the line of the arch, it is als o bei ng rotated "bout its long axi s, in a corrective mesio-bu cca l ro ta tory moveme nt. Since the sta inless stee l tube s pace maintainer will not allow individual movement of the ad jacent tee th, the di rectio n o f ro ta tion may be changed O f increased to fit oth er type s of rota ted pal a tal can ines, by tyin g the elastic

thread from th e eyele t directly to the premola r or la teral inciso r tee th. (b) M esial crOWII displ acement. This is very commonly seen in con jun ction wit h the me sio-llngua l ro ta tion th a t we have jus t descr ibed. Wh et her or not the rota tio n is prese nt, the proximity of the a natomic labial su rface of the canine to the la tera l incisor creates constraints on the p lacing of a bracket at the midbuccal position o f the canine crown. As a ge neral rule, this space is too small for the placement of any of the conventio nal b rack ets, which are so much bulkier. To ov ercome th is drawbac k, many p ractitione rs bo nd the conventio na l bracket, with its rigid and contoured base, on the irregular palatal sur face of the tooth, to which it is tot ally unsu ited. A fu rthe r d rawback is th at traction applied directly be tw een the bracket and the a rch wire will subst antia lly increase the ro ta tion of the tooth . Th is w ill be very d ifficu lt to co rrect la ter, and will sign ifican tly in crease the amoun t of mechanotherapcu tic ma nipu lation tha t the too th m ust undergo a-id the pe riodonta l prognosis of the tooth w ill be comp romised unnecessa rily . Traction from an eyelet placed in the ideal midbucca l position on the too th, e ven if it is more incisally placed becau se of the ph ysica l limi tati ons imposed by the proximity of the la teral in cisor, w ill bring about a corrective rota tional movemen t as the too th is d ra wn tow ar d s the ta rget a rea. Pa la tal bracke t-siting risks a com plica tio n (the de tach me n t of the b racket), and w hile it solves one problem (the impaction), it creates a no the r (increased rotation). It is rela tively easy to bond an eyelet close to the ideal mi d bu ccal position of the e xp osed tooth and to d raw clastic thread from it to the rigid tubing that has been pl aced on the a rchw ire to maintain the ca ni ne space in the a rch. It ma y be advantageous to tie the elastic thread to the bracket of the firs t premolar, to in crease the mesio-bu ccal rota to ry compone nt o f the traction. Th e premo lar w ill no t close d own the canine space, because of the presence of the s ta inless s teel tu bing. An extended pe riod of tra ction will, however, s lowly b ring abou t ad ve rse changes in the dental mid line,

PALATALLY IMPACTED CANI NES

by tipp ing of the incisors in the ligh t-wire techniques, unless mesial u prig hting sp rin gs are placed as ' brakes' on the incisors to increase their anc horage value . (c) Palatal root displacement. If the root apex of the canine is pal atally displaced, in addition to the palatal crown d isplacement, the crown will first need to be aligned in the manner that we have just described. Th is includes the cor rection of any possible rota tion an d mesial crow n d isplacement. With the canine crown in p lace and the main ar ch wire firmly ligate d into the newly su bstitu ted, conven tional bracket, the pal atally inclined lon g axis o f the tooth will d ictate that its palatal surface bul ges inferiorly, whil e the buccal su rface tips su periorly. The heavy arc h wire is now needed to serv e as the base arch to a labial root-torquclng auxiliary . Em ploying a full rectang ular arch, which is torqued in stage s on the canine on ly, the lon g-axis ind ination will be seen to im prove in time. At the same tim e, the roots of the ad jacent teeth, which provide the ancho rage for this di fficult movement, are themselves being torqued lingually, at each torque-ad justing stage an d then buccaUy as the tor qucing force is expended . Regardless of the type of o rthodontic bracke ts employe d, there are advantages to using a tor queing auxiliary that derives its ancho rage from the narrowed archform of th e ma in arc hwi re. This w ill avoid d isto rtion of the denta l arch, and will not create u nwan ted ' rou nd -tri pp ing' move ments of the adjacen t tee th.

tion w ith the palatal aspec t o f the root of the latera l in cisor (Fig. 6.24) and often sited between the roots of lateral and cen tra l incisors (Becker and Zilberman, t978). The tooth is not always pa lpa ble on the pala tal sid e. . Surgery

Surgical expos ure in this gro u p is complicated by the often u navoid able sim ultaneo us expos ure of the roots o f these ad jacent teeth. Agg ressive su rg ical tech niques may occasionally open the way for the or thodontist to bond on the labial surface, bu t no t wi thout con siderab le da mage to the adja cen t exposed inciso r roo ls by the radical removal of bone. With the position of the crow n of the impacted canine situated mesi ally to the root of the later al incisor, severa l operat ive problems present themselves. In the first p lace, su rgical expos u re has to be carefully undertaken, so as not to damage the roo ts o f the incisors. The temp tation to expose too Widely should be resisted, an d only enough of the

Group 2 • Proxim ity to line of arch: close • Position in maxilla: forward, low and mes ial to lateral incisor root The root apex of the canine in this gr oup is usually to be found in its correct p lace, in the line of the ar ch and at more or less the correc t height. The crown of the tooth, however, is tilted mes ially (forward) and in close assode-

Fig ure 6.24 The periapical vicw of an extreme example of j.;roup 2 can;J'Il.'S. Thl' 1l'f1 canine is located be tween lateral and cent ral incisor routs, and the right ca nine is mesial to the cen tral inciso r root.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH --"-:..::...--"-=====.:...=--"-.:...===~

120

most con veniently accessible su rface of the too th shou ld be uncovered, to permit bo nding. The palatal surgical flap should be replaced in its entirety, in order to provide max imum pr otection for the exposed inciso r roots and the area of exposed bone, and to reestablish a no rm al periodontium. How ever, to p rov ide an ex it fo r the tw isted ligatu re p igtail that is tied to the attach men t, the flap is divide d into two halves by a slit that is mad e w ith an electrocautery. ra ther than a scalpel, in order to p reven t bleed ing at the cu t

edge. The pigtail is passed thro ugh the slit, and the two-part flap is sutured back into place. Altern atively, the p igt ail ligatu re must

be carefully passed through a small hole (Fig. 6.25) punct ured into the flap, which is not easy to per form under these circu ms tan ces. The me sic-pala ta! rotation of the canine that is u suall y p resent in these cases places the labi al su rface of the canine in a com pletely inaccessible position . Th is mean s that only the palatal aspect of the cani ne is availab le fo r siting the attachment. Planning the orthodon tic strategy

From an eyelet p laced on the pal atal side of the tooth, direct traction to the labial ar chwire is sometimes possible. However, if traction is

Figu re 6.25

111f.' flap is fully

sutured back 10 its place, and the steel pigta il m ay be seen 10 emerge Ihl'01Jgh a needle-pierced hole in the flap.

pe rformed in this ma nne r, the attached su rface lea ds the way, and it will inevitably cause the canine to ' roll' over the roo t of the lateral incisor, to inc rea se the exisiting rotation (Fig. 6.26). Once the too th reaches the arch wire, the ope rator cou ld be faced wi th a l SOO rotation to pe rform! Few will di spute that this task is ve ry form id able, but, before the ad venturous clinicia n even begins to argue that it is not an im possible stu mbling bloc k, the following th ree qu estions sho uld be considered . How long will the de-rota tion p ro long the applian ce therapy? Will the rotational relap se factor be possible to overcome? Wh at w ill be the pred iction for the hea lth of the periodontium at the completion of correction of the iatrogen ic ro tation? For many of the im pacted teeth in group 2, the intimate relati on between canine crown an d latera l incisor root will block movemen t of the canine when d irect traction is applied . The inexperienced ope rator ma y then res pond by increasing the p ressu re applied to the too th, an d, wi thin a fairly short pe riod of time, there will be signs of loss of anchorage on the othe r teeth, ch aracterized by the p roduction of a crossbite tendency and a m idline shift from the affected side, not to men tion the possibi lity o f damage to the latera l inciso r root. A comp letely di fferen t approach must be used, in which the too th must firs t be moved in a d ifferent d irection to free it from its entanglement with the incisor roo ts. The mos t practical m anner of doing this is to d ra w it verticall y d ow nwards (towards the tongu e), erup ting it into th e palate, in an exercise aime d at converting the impaction into a gr ou p 1 case. It m ay then be moved directly across the line of the arch, towar d s the lab ial arch wire, in a seco nd movement. Three types of spring au xiliary may be u sed to bring abo ut the d esired movement that is needed initially, in this first stag e of the resolution . These are the ba llista (Jacoby, 1979), the active palatal arc h (Becker and Zilbe rman, 1975, 1978) and the ligh t auxiliary labial ar ch (Kornhaus er et el, 1996). In ea ch of these meth od s, it is esse ntial that a heavy base arch be tied into the brackets of all the tee th on the labial side, the aim be ing to hold the

PALATALLY IMPACTED CANINES

(.)

figu re 6.26 (a) A group 3 canine has been exposed , and hea ling is by secondary in ten tion (!). (b) An ed gewise bra cket (!) has been sited on the pa latal as pect of the cani ne. The tooth is being drawn from its pa lata l att ach ment directly to a flexible labial archwire (! ). (c ) The too th has reached the archwire, and is no w rotated a further 3O-4O Note the sw ollen appea rance of the gingivae and its poor contou r. Q

•

«)

opened space for the canine in the arch, to resist seco ndary di sto rtion of the occlusal plane and archform, and to provide a base from whi ch to apply the force to the tooth. The hollista (Figs 6.27a,b) is a un ilate ral spring of rectangu lar w ire, wh ich is tied into one of the rectangu lar molar tubes. It proceeds forwa rds until it is op posite the can ine space. At th is point, it is bent vertically do wnward s and terminates in a small loop. With light finge r p ressure, the ver tical portion is turned u p war ds, across the can ine spa ce, and tied into the pigtail ligature to lie close to the palata l mu cosa. In thi s way, torque is introduced into the ho rizon tal par t of the ballista, which is resisted to a g reat extent by the mo lar . The elasticity of the ba llista spri ng exert s p ressure for it to return to its original vertical po sition, wh ich, in tum, applies extrusive

force to the un eru pted toot h. If the impac ted tooth is fairly resis tant to move ment or if the di sta nce that the tooth nee ds to be moved is grea t, lingu al molar roo t torqu e may occur, representing a loss of anchorage. To overcome this, a rectan gular m ain arch or a solde red pa lat al ar ch may be used . The active palatal arch (Fig. 6.28a) consists of a fine 0.020" remova ble palata l archwir c, car rying an ome ga loop on each side. The wire is dou bled over at its extremity, to allow it to friction-fit into a soldered horizontal 0.040" tube on the palatal side of the maxillary molars. It is fur ther secured by a steel ligature tie and d istanced from the palate by gentle finger pressure. By elevatin g the downward-activated palatal archwire (Fig. 6.28b) and hooking the pigta il ligatu re around it, the unerupted tooth comes to be eru pted th rough the pa latal tissue, in a direction sligh tly away from the teeth.

122 _ _ _ __ _ __

THE ORTHODONTIC TREATMENT ____'--"-'----'-'-C --=-----=---OF IMPACTED TEETH __=___~

(.)

(h)

Fig u re 6.27 (a) The ball ist.l in its p.lssive mod e, pointing d ownwards. (b) Us ing ligh t fing er pressure, thl.' loo pt.->d end o f the spring is turned inwards and u p w ard s towa rds the palate, whe n ' it is latched in to the stamless s tee l pigta il fro m the u nerupted can ine.

The auxi liary labial wire is a third possibility (Fig. 6.29); it requi res no ad vance preparation of any so rt, s uch as the soldering of lin gual tubes. It is most conven iently fashioned fro m an archform blank of 0.014" d iam eter round wire by for ming a vertical loo p in the area of the impacted canine. Th is loo p has a sma ll termi nal helix. The auxiliary is tied int o all the br ackets of the arch, in 'p iggyback' style, with

the extrem ities slotted into a spare tu be on the mo lars, or left fret' d istal to the second prem olars. In a simila r manner to the ballista. the ve rtical loo p is activated by p ressing it palatally , across the canine sp ace, and ensnaring it in the pigtail ligaturc in the pal ate . Thi s is a pa rticularly u seful method for usc with a bila teral im paction, when two d ifferen t loo ps will need to be inser ted int o the arc h-

PALATALLY IMPACTED CANINES

[ a)

(b)

Figu re 6.28

(al The active palatal arch in if!; pa ssive mode, lying sever al rrullimetres inferior to the pala te and ~'n from the occlusal. (b) The s-ame \'iew after the active palatal arch has bee n gen tly raised towards the palate and ens nared by the pigtail hooks, tbe rcby applying ve rtically extrusive traction to the unseen canines.

form . Used w ithout a base ar ch (Proffit, 1992; Kokich and Mathews, 1993), it will extrude the ad jacent tee th and thereby alter the occlusal plane. It will mo ve the mo la rs bu ccally, and add itionally it w ill alter the horizonta l arch form in the incisor area. A mandibular rCII/ot'Ob1£' ap~'liance represents a met hod that requires no maxillary appliance at all, in the first instance (Or ton et al, 1995). Vertic al extrusive force is derived from a removable ap pliance in the opposing jaw, throu gh the agency of a latex elastic. This clastic is applied by the patient between the clasps of the mand ibu lar appliance and the pigtail liga ture in the palate. A ma xillary orth odontic applian ce is needed only when the tooth h as erupted thr ough the palatal mucosa . Rega rd less of wh ich met hod is employe d, the successfu l end -resul t will find the ne wly erupted tooth, su rro u nd ed by a wide rim of palatal mucosa and bone, in the middle of the palate (Fig. 6.30). The more the tooth is eru pted , the easier it will be to pla ce an attachment on its buccal sur face to enable the tooth to be moved bu ccally, without the bracket 'im pinging on the g ingiv a . Howe ver, an excessive ly erupted tooth will lead to

occlu sal trauma as it moves acros s the line of mandibu lar tee th . For the first stage o f the two-s tage manoeuvre, the position of the eyelet is immaterial. Therefore bon d ing is pe rformed to the mos t convenient surface ava ilable, since no ad verse rotation o f the too th will occur whi le it is bei ng moved vertically downward s. The too th is cleared of the latera l inci sor roo t an d moved until it has an unobst ruct ed path to the arch wire. A secon d ey elet is bonded to the tooth , this time on the m id buccal aspect, which will ha ve become accessible as the result of the initi al orthodo nt ic movement. The second stage of traction may then commence, with the application of force from the second eyelet di rectly to t he labia l archwire. The poin t shou ld be mo de tha t in this case. and in any othe r group or situation, direct trac tion to the archwlrc shou ld on ly be pe rformed from an atta chment sited in the midbuccal position of the tooth . Traction applied at an y ot he r site w ill enge nder an u nwa nted rotation as the too th p rogresses towards its p lace in the ar ch - a rotation that will requ ire cor rection in an ex tra and su perfluous phase of orthod ontics.

124

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - -- - - - - -- - - - - - - - - - -- -

(4)

(b)

«)

Figure 6.29

(a) lnitinltreatment has created space, and a hea vy base arch ca rry ing a stainless st ee l tu be spa ce m ainta iner is in

place. (b) A typical a uxiliary labial ar chwirc of 0.014" gau ge with its vertical loop an d terminal helix. (c) The a uxiliary labia l archwire is tied o r pin ned into the brackets 'pimback' over the heavy base arch, immt'd iately prior to surgical exposure. (d) Following the full flap closure, the vertic al loop is gently turn ed inwar ds and upwa rd s, with us helix secured inlo the terminal hoo k of the piglaiL This is the same case as in Fig. 6.25. (d)

125

PALATALLY IMPACTED CANINES

comes in to close relation w ith the ad jacen t teeth . The orthodont is t shou ld not relinqu ish the use o f the eye let until no furthe r buccal m ovement is needed .

Co mp licat ions The in itial location of the too th may be co mp licated by one or both o f the following cond itions. Fig Ull! 6..30

The tooth ha s eru pted ap propriately, and is ready for its buccal traction .

Problems that may be encountered

On occasion, the palatal tissue is very res istan t and bu lges more and more as the tooth p rogresses, bu t does no t allow the tooth to erupt (Fig. 6.31d). This ev entua lity w ill necessit ate a very limited and superficial su rgical removal o f the th ick mucosa immediately over the crown of the tooth. The anterior palatine artery is located in this im med iate area, an d care should be taken not to sever it, in w ha t is otherwise a very simp le procedure. Once the tooth is we ll er upt ed, at the level of the occlusa l plane, a new eyelet attach me nt is bond ed to its anatomically buccal sur face (Fig. 6.31e). It is then drawn in a di rect line to the labial archwire and to th e place where s pace will have been p rovided for it in the initial or thodon tic phase of the treatment. Initia l rotation of th e can ine w ill s till be present when th is second phase of the traction beg ins, bu t it will cor rec t steadily as the traction procee ds, with the attachment and buccal sur face lea ding the way. Eve n with good oral hygiene during the trac tio n pe riod , mu ch exuberant gingival tissue precedes the canine during its m igra tion towards th e line o f the ar ch. The premature use o f a con ven tion al bracket may res ult in tissue imp ingemen t, pa rticu larly as the tooth

(a) Rotation. As w ith the g roup 1 canine, a mes ic-l ingual rotat ion is common, and it is largely corrected during the seco nd stage of resolution. when traction is made from the second ey elet, on the bu ccal surface of the tooth. (b) Palatally displaced root. Occa siona lly a tooth in thi s group ma y p resent with the root palatally d isplaced , in ad di tion to the crown (i.e. a palatal translation of the entire tooth). Its occu rren ce will complicate the ap pliance work by requiri ng the intro d uction o f buccal root to rque and often some me sio-di stal root uprighting. These forces may onl y be app lied once the crown has been en gaged by the main lab ial arch wire. H will be app rec iated that a grou p 2 can ine ha s to be approac hed with a good measu re o f p reparedness. From the su rgical point of view, access is not d ifficult, but exposure must be performed carefully 10 avoid damaging the ad jacent teet h. The orthodontic appliance may need to execu te as many as five different types of mov ement, involving both crown tipping an d roo t movement, i.e. ver tical extrusion from the palate, buccal tipping to the line of the arch, ro tation, mesio-di stal root u prigh ting and buccal root torque. From the periodontal po int of view, the p rognosis of the resu lt is dependent on the smooth executi on of the surgical and orth od ontic opera tive proced ur es. Mism anagement o f both the orthodontic and the surgical s tages ma y not be germane to the question of wheth er the final alignmen t of the tooth will be technically s uccess ful, but it will be critical in determ ining the final bone level (Figs 6.31j,k ) and period on tal cond ition that m ay be ach ieved (Figs 6.31g,h ).

126

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

----------------------

C,j

(h)

(e j

(d)

Figu re &.31

(a) A grou p 2. ra nine in ,1 t z-ycar -otd f('malt' has been minimally exposed on its palatal aide. The tip of the cusp has not been exposed. An ey elet attachment has been bon ded to. the palatal side. (b) Suturing is co m pleted, with the pigtail l'meq; inlllh ruu gh the divided nap . The palatal arch is prepared fo r ligat ion. (e) The palatal arch fu lly tied-in and active . (d ) Seen 3 month s lat er, afte r two in tervening visits for adjustm ent, th e ar chwir e has bec ome di st anced frum the palate , and the canine can be S,'(' O to bu lge ttll' contour of the palate almost to tht' occlusallevel. (el The decid uou s canine was t'xlr,ld l'd .11 th... sa me time .1S the minim al re-expcs urc was performed , pre pa rlltory to buccal movement. A sec ond eyelet is bon ded sllghtly mesi,11 to the m id-buccal po sition, and elastic ligatio n is dra wing the too th d irectly to the archwire. wttha favou rable rotJt ioll vector from the sec ond eyelet. (f) At 13 m onths pos t-surgery , the C,111ine is in the orch, and a br,lC~et is substituted fo r the eyelet. (g. h ) The gingival hea lth of the treat ed canine b good, but its clinical cro wn is longer th an lh,' unt reatedleft canine. (i) Th,' pe riapical view. Noll,' the re irbed mo t ,1"".')< of riKhtl at" fal inciso r. (j. k) Post-treatmen t p•.'ri" pic,11 vi,'ws to show compar able bo ne sup port of treat e l and un treated canines.

PALATALLY IMPACTED CAN INES

I Figurt> 6.31 ro"tillUed )

«(')

If)

(g)

•

I (i)

(k)

126

THE ORTHO DON TIC TREATMENT OF IMPACTED TEETH

Group 3 • Proximity to line of arch: close • Pos ition in max illa: h igh

The roo t a pex o f the can ine in th is group is situa ted ve ry h igh in the ma xilla, although mo st ofte n in the gener al, bucco-llngual, line of the arch a nd in its correct location in the

antero-posterior plane . The crown is high and only relatively mildly displa ced palatally, and it is no t usua lly palpab le. Surg ical and orthodontic strategy

Access to this tooth may be eithe r fro m the buccal side or from th~ pal ata l side, w ith advantages and disadvantages to both approaches, since there is a s ignificant thickness of bon e medial and lateral to the tooth . Consi de ra ble bo ne re moval is needed to reach it from either side, w ith s imila r d ifficulty in the applicat ion of an attachme nt. Th e o rthodontic t rea tme nt entailed in align ing such a tooth involve s principally extrusion, together with a bu ccal tipping movem ent. The buccal approach

From the bu ccal side, the tooth is a pproa ched as for a buccal impaction, w hich was described in Chapter 3. The surgeon may have grea ter difficulty in locating the im pacted tooth, and w ill be more de pe ndent on the radiographs. Th e apically repositioned flap (Vanarsdall and Com , 1977) woul d, a t firs t s ight, appe a r to be a go od approa ch, since it offers su itabl e access for the ap p lica tio n of ort hodontic force d irect to the archwtre. It also en sures tha t an adequate band of atta ched gingiva be raised above the le vel of the impa cted tooth and the n accompany that too th in its subseque nt d ownw ard pat h . From the su rgical poin t o f view, ho w ever, this approach takes no account of the threedimensional locati on of the cani ne . Th e method mav be ve ry suitable for a buccal canine who~ vertical d isplaceme n t is rel atively mi nor, bu t in the case of a mo re su periorly displaced pal a tal ca nine this ty pe of exposure wou ld leave a con sid e rab le e xpanse

of alveolar bone open to the oral e nvironment and the flap su tu red several millimetres lateral to the crown o f the tooth. Furthermore, the main tenance of the exposure of a ca ni ne crown, palat al to the line of the a rch, wou ld secondarily ca use a d enu d ing of the interp rox imal a reas of the roo ts o f the ad jacent lat eral inc isor a nd firs t premol a r tee th . Th is method is on ly su ita ble for cases of ve ry minor palatal di splace ment. Fil II flap reflection and its subsequ ent pa rtia l re placement ove r the expose d too th, toge the r w ith the placemen t of a su rgical pack, has bee n u sed for man y yea rs, and was w idely advocated (Lappin, 1951; Johnston, 1969; Lewis, 1971; von dcr Heyd t, 1975) for a palatally impacted canine. In the case of a group 3 canine, a considerable thickness of al veola r bone is present both inferiorly and infer io-buccel ly to the ca nine, which must be traversed by the too th . In ord e r to overcome this physical im pe d im en t, the above a ut ho rs h ave recommend ed the surgical cha nnelling o f bo ne, to free a p ath in the d irection of the dental arch (Figs 6.32a-e ). Experience with thi s procedure shows th at, w hile it lives up to its expect a tio ns regar d ing the p rovision of access a nd the enab lemcnt of d irect traction, it d oc'S so only by the p lanned sacrifice of much of the bone of the immed iate area of the alveola r p rocess! The treated resu lt (Fig. 6.32d ) then leaves an aligned canine with an unacceptably reduced bone su pport and a m uch poorer periodontal prognosis than cou ld be achieved by other mean s. The tunne l approach

An excellent modification of th is method h as recently been de scribed (Crcsd ru ct al, 1994) in which the buccal plate of bon e is preserved, w hile the im pacted tooth is d ra w n throug h a tu nnel in the bo ne provided by the vaca ted socket of the sim ultaneously extracted deciduous canine (Fig. 6.33a). Th e sa me full flap is reflected an d the impacted too th e xposed, leaving the buccal plate in ferior to it intact. The deciduous canine is extracted, and its socket is extended and w idened su fficiently to allow the passa ge of a fine w ire th rough it as far as the im pacted tooth.

PALATALLY IMPACTEDCANINES

(.j

(bj

«j

(dj

Figure 6.32

(a.b ) The grou p 3 canine has been exposed from the buccal side, and bone has been channelled to clear a direct pa th to the arch wirc. (c) With the band cemented to the canine, the radical nature (If the surgery may be seen. (d) The ,lligm'd

canine shows a long clinical crown and a lack of normal bony contou r. Note the deficient interdental papillae.

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

130

(b j

,.j ,<j Fig ur e 6.JJ (a) The ' tunnel' approach. NOlt' the pn..'SI.'rva tion of the buccal plate in teri or to the too th . The s tainless steel pi gtail is d rawn inferio rly through the vacated soc k.. t of the deci d uous canine. (b) At 2.5 mo nt hs posl-su rgt' ry, Ike "slingshot' elas tic mod ule has brought the (a ninI.' into d buccally palapable posi tion. (c ) 1 ymr after comp letion of trea tmen t. N ote the gingival h.. ight, w ide atta ched g ing iva an d good bo ny con tou r.

An eyelet att achment on steel mesh is thread ed wit h 0.011" soft ligatu re wire , read y for bond ing to the new ly exposed impacted canine. Following appropr iate acid etching of the e namel surface, the a ttach ment is load ed w ith the bonding ag en t, a nd its s teel liga ture p igtail is lightly curved an d threaded into the im media te area of the exposed too th and on into the p re pa red tunnel un til it emerges fro m the occlusal end o f the deciduous canine socket. At this point. the eye let att achmen t is pressed firmly into place on the impacted tooth.

The surgical flap is resu tured to its fo rme r p lace, and visua l contact wit h the im p acted tooth is los t. Co ntro l of fu ture m ovemen t of the ca ni ne is exe rcised thro ugh the ap plication of force to the steel pigt ail ligatu re, w hose ex trem ity may be seen to e xte nd th rough the sutu red edges o f the fla p. w ith in the decid uo us canine socke t. Any excess in its le ngth is cut, and it is fashioned in to a small h ook, to w hich ela sti c tr act ion may be applied . The su rgical method affords good access to the canine and a minor degree of difficulty in

PALATAllY IMPACTED CANINES

threading the ligature. Or thodontic traction may be efficiently applied, an d the treatmen t result shows a good bony p rofile and an un compromiscd pe riodon tal resu lt, sim ilar to that seen on normally eru p ted teeth (Cresciru c t al, 1994 ).

'...

.: ~ .e.;;...

The palatal approach

With the crown o f the canine sligh tly mo re palatally d isplaced, su rgery on the buccal side needs to becom e more radical, rendering a palatal app roach preferable. Follow ing the ra ising of a palatal flap, the can ine will be revealed high up, pal atal to the roots of the adjacen t teeth, wh ich occasionally may themselves become d enuded in the process. Infer ior and lateral to the can ine is the vertical wa ll of the alveola r process. Bond ing of the eyelet attachm ent is perfo rmed in the usua l ma nner, to the most conven iently accessible site, which is the palatal side of the too th, alth ough the buccal su rface, d ose to the tip, is occasionally poss ible. In this situa tion, many su rgeo ns w ill remove a part of the flap in order to leave the impacted tooth in visual cont act with the exteri or and will place a pack to cover the open area . If the sta inless steel pigtail liga ture is drawn towards the line o f the arch an d su tu red into place so that its extremity comes th rough the d eficien t pa rt of the flap, the application of or thodonti c forces w ill give rise to sig nificant d anger o f irr itation and infection of the area. Th is is caused by the too th being d rawn buccally and vertically d ownwards by its ligation to the labial arch wire.T he res ul tant direct ion of this force will cause the impacted canine to be draw n late rally against the alveolus and its healing gra nula tion tissue. The exposed tooth will becom e rebu ried in these tissues (Fig. 6.34) as it proceeds do w nw ards and buccally. Th is leads to inflam mat ion, false pocketing and the likely occurrence of an acute lateral pe riodontal abscess. It is therefo re advised that ort hodontic stra tegy for grou p 3 canine'. S be altered, by d ividi ng its reso lu tion into two distin ct stages , as wit h gro u p 2 canines (Fig. 6.35).

Figu re 6..34

Direc t traction canine .

Wf5US

two-stage tracti on in tho! gro u p

3

Orthodon tic traction is first ap plied in the lingua l and vert ically downward di rection, to erupt the tooth into the palate, palatal to the line of the arch and brought down to the occlusal leve l. As it comes down, it is accompanied by a w ide collar of new ly formed alveolar bone. At this po int, an ad d itiona l eyelet sho uld then be pla ced on the b uccal aspect, as fo r a grou p 2 case, and the d irection of traction altered to a pu re buccal tip ping movemen t, to bring it int o the ar ch. It is often possible to bond a convention al bracket to complete this

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

(bj

' oj

Figure 6.35 (a) A group 3 canin\' t·xpoSl..od and viewed from the occlusal aspect to show the attachment bonded nc ar the tip of the buccal side. (h ) six weeks later ,10<.1 without fu rther adjustment. the canine has erupted through the closed flap. (c)

Buccaltraction to the buccally placed eyelet. (d.e) The bucca l and palatal views of gingi val tissues on the treated side, 16 months post-su rgery. (f,g) The same views of the nonnal side. (h.i) Periapical views of the treated (right) and un treated sides, showing compa rable bo ne s u p po rt levels .

PALATAllY IMPACTED CANINES

(Figure 6.35

am/i,wM )

(.)

Cd'

cn /"

(g)

Ch'

(i)

'34

THE ORTHODONTIC TREATMENT O F IMPA CTED TEETH

- - - - - - - - - - - - - - -- - - - - - secon d stage if the re is eno ugh gingi va l clea rance on the buccal su rface of the too th , althoug h this m,1y not be necessary. Since neither rota tion no r ectopic root apex position is common in these cases, the second-stage tipping moveme nt ge ne rally brings the canine in to its desi rabl e position a nd inclina tion.

The canine tha t is loca ted in the position tha t w e hav e d escr ibe d here p rese nts di ffer en t problems fro m the grou p 2 CiISCS. Direct traction is, u nder these circu mst ances, technically possible, but per iod on tally hazardou s. The mos t d irect s ur gical remed y (from the buccal side) is too rad ical a nd leav es the too th relatively unsu p ported by bo ne, in the final ana lysis, unless the ' tunnel' a pproach (Cresc ini et el, 1994) is used. How ever, for the pala ta l approach, ca reful two-stage orthodontic mo vement will req u ire min im al surgery and avoid u ndesirab le periodonta l sequ elae. The principal feature th a t di s tingu ishes the group 3 case from the sim p le a nd s trai gh tforwa rd group 1 case is its rela tive height in the alveolus. The roo t a pex is u su all y in the line of the ar ch, a nd the crown is only rel atively minima lly d isp laced palatally, w hich of ten mea ns tha t the too th cannot be pa lpa ted. The group 1 ca nine req u ires a minim al degree of ver tical developmen t in the mechanothera py, an d m ainly a bu ccal tip ping movement from its more se vere pa latal position. Th e group 3 canine, on the other ha nd , has primarily to be extru ded ve rtically. If only a very mi no r buccal component is needed then a bucca l at>" p reach to s ur gery, usin g th e ' tu nnel' method , may some times be ad vantageous.

Group 4 • Proximity to line of arch: d ista nt • Po sition in max illa: high Whe n the cr own of the palatally d isplaced canine is not di rectly rela ted to the roo ts of the incisors, it generally po in ts medially and app roaches or e ven cr osses the mid -pala ta l suture (Fig. 6.36). It is not al w a ys palpable in the pa la te.

Surgery

These teeth arc generally a t some d is ta nce from the ad jacent teeth, a nd little bone removal is needed to expose the m, w ith scant d a nger of expo sing the roots of othe r tee th . Th ere is us u ally reasona bly good access for the place ment of a bond ed a tta chment, although the immed iate exposed su rface is unlikely to be the b ucca l as pect of the tooth . Planning the orthod ontic strategy

Since ther e is no r mal po sitio nin g o f the roo t apex in most of these cases, all tha t wou ld a ppear necessa ry is to draw the too th d irec tly to the labial archw ire. If the long a xis of the too th is dose to the horiz ontal plane, it would be ina ppropriate to do thi s, s ince the direction of this force would be virtua lly coincide nt w ith its long ax is. This makes the mechanics highly ine fficient, a nd little progress in rt..'Sol ving the im p action w ill be seen. Th e proced u re w ill become excessiv ely taxing on a nchorage, an d w ill give rise to n rcacnvc moveme nt of the e ntire maxilla ry d entitio n. With the too th close to the horizon tal, a mo re ca utious approach should be em barked upon. A wi d e downward tipping mov e ment w ill be achieved more efficiently with the same vertical directional ap proach that ha s been described for u se in group 2 an d 3 cases, with the u se of s prin g aux iliaries . Wer e the fulcrum for this w id e tipp ing movemen t of the ca ni ne to be a t the roo t end, then it w ould follow that the root apex position would be u nch a nged when the cro w n final ly reach ed its d estina tio n in the lin e of the arc h. Un fort una tely, however , the fu lcru m is us ua lly some sho r t wa y along the a p ica l portion of the roo t, a nd the refore , d u rin g the alignment of the too th, there will be a co nco mt ttant p alatal d isplacement of the roo t apex of the canine . Thus some buccal r oo t torq ue of the group 4 canin e w ill later be necessary. The refore it also follo ws th at in the unusual situa tion where there is a pa latal d isplacement of the root apex a t the ou tse t, m uch torque will be req uired , and this prese nts a major clin ica l pro blem .

PALATALLY IMPAC TED CANINES

Problems Torque canno t be ap plied until the cro wn of the too th has reached its pl ace in the arch and its conven tion al orthodonti c bracket firml y en gaged by th e labial archwlre. At that ju ncture, the cro wn of the can ine is at the occlusa l level and has a st ro ng bucca l tilt. This pla ces the pa latally d isplaced roo t lew in th e pa late, with its profile clea rly outlined und er the mu coperiosteum. That cri tical po rtion of the lingual side of the roo t closest to the crow n of the canine has a marked ly convex sh ape, which di ctate s a di stinct bulging of the mucosa cove ring it. In the clinical context, some dehiscence of this lingu al area of the cemen ta -enamel junc tion is us ually present. Add itio nally, the cingu lum area of the palatal aspect of the cro wn is very prominen t, and is likely to interfere with the occlus ion. It is importa nt to recognize tha t in g roup 4 cases an d many group 2 cases, conside rable lateral movement of the ca nine is required, most of which involv es tipping. Quite freq uently, buccal root torque is also needed, and this may be quite considerable, pa rticularly in the pr ese nt group. Accord ingly, there is an equal an d opposite reactive force acting over a long pe riod on the en tire a nchor u nit, w hich, if properly planned an d prepared, w ill respond only minima lly. Th is w ill be express ed as a movemen t of the dental mid line to the o pposite side and a cross bite tendency on the sa me side. In order to m inimize this, a heavy base arch s hould be used , and its for m should be alt ered to com pensate for the expected movements. A bilaterally affected case p rov ides the op portunity for nu llifyin g loss of anchorage by pitting one side against th e other, suc h that mid line and arc hform alt erati ons need not occur. To summarize the group 4 cases, the clinician must be alert to d ifficu lties in th e mecha nics that the loca tion of the canine provide. Ca re mus t be taken to preserve ort hodontic anchorage by properly planning the mec hanotherapeutic stra tegy of reducing th e canine displace ment. The practical limitations Imposed may lead to adverse effects on the

period ont ic sta tus o f the lingu al aspect of the too th, whe re occlusal interference mav be present in the interim until the roo t position is corrected .

Group S • Can ine roo t apex mesial to that of late ral inciso r or d istal to tha t of firs t premolar. This tooth s ho uld be consi dered as a transposed tooth. To be completely consis tent w ith th e definition of transposition, the canine apex s hould be in the line of the arch, in the place of the root ape x of the adjac ent tooth, but it is ind epende nt of me sio-d is tal or buccolingual crown locati on . Surgery Many of the transposed canines are at leas t pa rtially erupted, wh ich obviates the need for su rgery. It is not possible to id entify impaction trends amo ng the remainder that might suggest a part icu lar ap pro ach to their expo su re. Rather, each should be su rgically exposed in line with its own pa rtic ula r demands and circu mstances. What is tru e is that several of these may be so d isplaced tha t mod alities of treat me nt other than orthcdontics sho uld be consid ered, par ticu larly extration and pros thetic replacement or, p referably, reten tion of the deci d uou s cani ne. Planning the orthodontic s trategy The canines in group 5 ma y be offered four possible lines of treatmen t th at arc appropriate proc edures for their resolu tion : (a) to reso lve the transposition to the id eal relatio ns hip (Fig. 6.37); (b) to move the p remolar me sially (or incisor d istally) into the can ine loca tion and alig n the canine be tween the two premolars

mg . 6.38);

(c) to u se th e canine for auto tra nsplan tation

into a p repared soc ke t in its ideal site; or Cd) to ext ract th e sev erely displaced canine, incisor or premolar, depe nding upon

136

_ _ _ __ _ __

THE ORTHODONTIC TREATMENTOF IMPACTED TEETH _ _'-'-------"'-"----'-'-'-----=--'-'------=e.-.=_

('J

(b)

,e'

,d,

Fig ure 6.36

(a] The active palata l arch in pla ce to cru pt a group 4 caoinl' that has traversed the midline , (b) Post-su rgical peria pica l radiograph shows space opening and an active palatal arch ligated to the bonded attachment. (e) After 3 months of traction. minimal re-expo sure of th e no w Vl'ry superficial a nd palpable canine was pe rfo rm ed . A po ste rior componen t w as achieved using elastic thre ad to the lingual tube of the molar of that side. (d) tusec-bcccat followed by purely buccal traction was also performed. Dista l up righting an d buccal root torque were later need ed . (e, f) Intra-oral views to compare the buccal gingival health and clinical crown length of the treated (right) and untreated canines. (g..h) The same oro the palatal side.

PALATALLY IMPACTED CA NINES

(Figure 6.36

co'IUmm l)

(h)

138

THE ORTHODONTIC TREATMENT OF IMPA CTED TEETH

- - - - - - - - - -- - - - - - - - - - - -

(, )

(0)

(b )

Figu re 6.37

(",1:» A maxillary canine/ first prem olar

tr,m~ p()s i tion,

(b)

treated 10 reverse the tr an sposition .

w hich has the least cha nce to be alig ned w ith a good p rognosis. Mecha nothe rapy ai med a t red ucing transpo sition a nd bri ngin g the too th to its correct position in the d ental arch is frau gh t w ith difflcul tv. Wh ether the crown of the ca nine is

d rawn d irectly towards the labia l archwire or only af teran initial ve rtic al tr action p hase, the ca nine' s roo t will inev itably co me into d ose relation wi th the roo t of the adjace nt first premo lar or la teral incisor. Root conta ct in group 5 cases creates a mechanical cou ple. The continued a p plica tio n of force fro m the labial a rchwi re will d ra w the crown o f the ca ni ne ever closer, although wit h greate r d ifficu lty an d ta kin g consid era bly more tim e.

(
Figu re 638 (a, b ) Ca mne /Iateral inci"",r transposition see n in lra o ra lly and on pancrarmc radiograph . (e) The completed alig n me nt o f the tee th in the tra nsposed o rder. G rind ing of the incisal edge of the lateral incisor need s to be pe rformed to avoid occlusal interfere nce an d to im p rove i1ppc.lrilna'.

PALATALLY IMPACTED CAN INES

Prob lems that may be encountered

If we assu me that the en tire canine tooth is palata l to the line of th e arch , the secondary effect of the root con tact will rotate the canine's root apex, both mesially and palata lly, across the palate, in a wid e sweeping movement. The toot h will become 1aid ou t' immed iately beneath the periosteum, an d the long p rofile of its root will be pa lpa ble und er the palatal mu cosa. Dehiscence of the cervical area of the root surface will occur (Fig. 6.39). The amo un t of u navoidable labial root torque tha t w ill then be required will be extreme and beyon d therapeutic reason. If the can ine position is buccal to the root of the ad jacent tooth and the tooth is brou ght buccal to the first premolar or the lateral incisor, further bu ccal d isplacement of its root will occur, with gross dehiscence of the buccal periodontium. To achieve complete and id eal o rthodontic alignme nt o f th e gro u p 5 canine, while minimizing these severe pe riodontal consequences, mechanothera py would need to be aimed at both tra nsposed teeth. The root of one would need to be torq ued in a lingual and then d istal flanking movement, while the other would need to be torqued in an op posite bu ccal and mesial flank ing movement. In this way , neither would be di splaced too far

Figu re-6.39

A 1ilid-ou l' camne d Ol.' to contact of the canine wit h th e roo t of the p remola r duri ng tractio n. (Courtl'Sy of Dr Y be n a,....... 1.)

fro m the line of the arch, and , whil e each wou ld undoubted ly suffer pe r iod on tally, this would be less tha n than eithe r one ind ividually. It wou ld be of grea t help if a pra ctical method cou ld be d evised to perform these d ifficult movements on an un erupted tooth, wh ile th e cro wn is too d istant to be ligated into the labial archwire. Wh ile each of the above four trea tme nt possib ilities w ill be recommend ed in specific ins tances, it becomes clear that the most likely and practical course w ill be to recognize and accept th e transposition . The canine shou ld be bro ug ht into the dental arch with the first and second p remolars (or between cen tral and lateral incisors) as its mesial an d d ista l neighbou rs respectively. 'Macho ism ' may be the d riving force behin d the d ecision to p lace the teeth in their correct order, since, after all, we are or thod ontists and this is the sort of challenge for whic h we have been trained . It is d ifficu lt to pa ss nve r an opportu nity to d isp lay our initiative, our dexterity and ou r clinical excellence. Sometim es this is justified - bu t not often. It should always be remembered that the reversa l of a tran sposi tion dictates, of necessity , tha t the tw o teeth have to pas s by one another in an alveolar p rocess whose buccalingua l width is sui table for just one of them. True, when teeth are moved bu ccally or lingua lly on the ridge, there is a concom itant bucco-lingu al expa nsio n o f the alveolar bone. Clinically, however, there is loss in bon e heigh t, and a dehiscence may occur, particularly if oral hygie ne is inad equ ate. Fur thermore, the bio mechanics is dif ficult to perform with adequate TOot con trol, an d root p roximity may occur du ring the exercise. This could ser iously com promise bone su pp or t on that su rface of the two roots, and some loss of attachment or even roo t resor pti on may occur.

Group 6 • Erupting in the line of the arch, in pla ce of and resorbing th e roots of the inciso rs

140 _ _ _ _ _ _ __

_

Why u ne ru pted pe rmanen t tee th . w hich are in close proximity to the roo ts of their neighbours, cause resorp tion of the roots of neighbouring teeth is u nclear. Ho wever, when it does happe n, it is aggressive and u sually non-sym p toma tic. The presence of follicu IarZd cntigerou s cysts, which ma y dis p lace the root s of the .adjacent teet h, is not gen erally ass ociated with the ir resorp tion (Brill et al, 1993a; Ericso n and Kurol. 1987a,b). However, root resorpti on of the lateral incis or is d iagnosed far more frequently when this too th is of norma l size than when it is small or pegshaped. In other wo rds, in those cases that show the typi cal p icture of associa ted an omalies described ea rlier in thi s chapter, the likelihood that the y will exhibit roo t resorption is s mall (Brin ct ill, 1993a). Given that th is type of resorption is rap id ly progressive, d iag nosis and treatment decisions must be mad e s peed ily. The condi tion cons titu tes one of the ve ry few situations in whic h orthodontic trea tm en t may be con sidered a quasi-emergency . Periapical radiography will help the clinician to diagnose and assess the degree of existing resorption , but p recision in d eterm ining the ang ula tion o f the tu be to the too th and the film m.1Y be cri tical in these cases . Subsequen t radiographic follow-up o f (a) the changing posit ion of the canine, which is being elicited by the mechanotherapy, and (b) the progress of the resorption pr ocess is the only practical method available to monitor the resolution o f the problem . Accordingly, peria pical radiographs , taken without regard to s tan da rd ization, \v i11 lead to the d rawing of ina pp ropriate conclusions on bot h scor es. Lateral views of the
THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

----'...:::..::...::c-'-=-'--'----=--:..~=_______'__.::=___==

an d mesio-distal plane. In ord er to achieve the most definitive d iagnosis of the extent of the resorption and the position of the associated canines, compu ted tomography (CT scann ing) will be of grea t help. Accord ing to Ericson an d Kurol 0 987b), reso rp tion occurs more freq uentl y in palatal canine cases than is generally recor d ed or noti ced by the orthod on tist. This wo u ld ap pear to be due to the fact that man y of the cases wit h mild pathology remain undt agnosed . However, these are not the cases that belong to group 6, since the resorp tion process in minor and su pe rficial areas of root su rface will generally cease to be active once th e position of the canine has altered , and the lon g-term prognosis o f the canine a nd the tooth ex hibiting the resorption will no t be endangered. These cases may be more logically an d more conven ien tly p laced in other groups , particu larl y gro up 3. Group 6 is reserved for those ca nines that are associa ted with or have the po tential for significan t loss of root length of th e ad jacen t tee th and that are actuall y erupting into the area formerly occupied by the d isappearin g roo t (Fig. 6.40). As suc h, they are not genetally pal pable, since they are situated in the same bucco-lingual plane as the incisors. The root apex may be dose to its ideal positio n, in the line of the arc h. However, the apcx--eusp orientation of the canine is alm ost invariabl y d ow nwa rd s and mesi all y, wi th a slight med ial
PALATALLY IMPACTED CANINES

and buccal tip ping of the tooth towards the archwi re is unsuitab le, since this always involves some downw ard mo vement, whi ch will aggravate the reso rption of the more inferiorly placed rem aind er of the roo t. The u nchecked ad van ce of the canine may cause total reso rp tion and shed ding of one or more of the incisors, a nd it will place the canin e in a finally erupted position, where its ap peara nce is un acceptable and its use as a prosthetic ab u tment is equally inapp rop riate, because of angu lation. Su rg e ry and the planning of orthodo ntic strategy Two possible escape rou tes are available to retrieve the crown of the canine from the area, in the effort to salvage as much of the incisor as possible, while improving the position of the canine and its p rog nosis. The first rou te necessitates a pa latal surgical app roach (Fig. 6.40) to place an att achment on that aspec t of the toot h first exposed , ,v-ith extreme care being exercised not to extend the exposure furt her tha n is necessary in any d irection. Ort hodontic traction is then applied to move the crown posteriorly in the horizontal plane, in a d irect line toward s the ma xillary molars, without incorporat ing a vertical d ownward movement. In this way, the crown will follow a poster ior and med ial circuitou s pa th arou nd the fulcru m of its root apex. Once it has erupted through the palatal mucosa, an eyelet is placed on its bu ccal aspect and the tooth may be safely drawn to the archwire. The second rou te requires an exposure of the tooth from the bu ccal (Fig. 6.41), erring on the side of a mo re su per ior app roach, in order to red uce the risk of sim ultaneously exposing the root of the incisor, whic h will be in the same bu cco-lingual plane. The aim would then be to move the tooth buccally, hor izontally and slightly superiorly, over the shor tened incisor roo t stub and to convert it in to a buccal canine. Prob lems that may be encountere d If the case is first see n very late and root

resorption of the incisor has de stroyed two-

thirds or more, it is usua lly mo re reasonable 10 remove the incisor a nd to d raw the canine

d own into its place
'42

THE ORTHODONTiC TREATMENT OF IMPACTED TEETH

- - - - - - - - - - - - - - - - - - - - - -

(b)

(0)

Cd)

Hgure 6.40 (,l-c) From t h~' lateral cephalometric film, the anterior occlu sal film a nd p anoramic scan, th e canines a rc seen to be eru p t-

ing inlo the place of the resorbing Toots of the a-nt ra l incisors in this 15-yea r-old female. (d) This case W,lS trea ted 24 yl'i!rS "go, when bands were used and healing by secondary intention, u ~ing p,IC~, was ro utinl'. .'\J" ll' the usc of the sol-

dcrcd pal.:llal arch for force application for posterior traction . (e) Th", canines have eru plt.'d into the palate, well clear of the apices of the incisors. (f) The (aninI'S arc move"lJ bu ccally. tg, h) In tra .....ral \'iewl>of the co mpleted result. No b rackets were placed on the ant ..rior t eeth-th.. inciso rs we re align ed usin,li; the re'!.li nl·rs. Therefo re 1l1"C'b.·...Uy root torque of the left caninl' wa" no t pcrlomwd. Bo th laterals shed wit hin a ycer post·tn·atml'nl. Some years later, the right ca nine a nd both cen tral inciso rs were incorporated into an ext l'nsin' fixl-.J bridge. The Idt ca nine was extracted MilUM" of probI..ms with parallelism. (i) an ant ..rio r occlusal radiograph of the (tl'mporary!) fixed bridge, 22 yea"" after completion of orthodontic treatm..nt. showin,.; complct...a rres t of the resorpnon pr...c.....••.

PALATALL Y IMPACTED CANINES

(figu re 6.40

CfmlilIJH~/)

Col

Cgl

(il

(h)

144

THEORTHODONTIC TREATMENT OF IMPACTEDTEETH

- - - - - - - - - - ='------ - - - --

,.J

,
-

-

--

IbJ

'dJ

Fig u re 6.41

(a,b) rl'riapicaJ \.,ews of the gro up 0 cani ne with associated severely resorbed cen tra l inciso r. CC) A varian t of the auxiliary labia l arch to move a tooth huccally. The loop is d rawn upwards and into the sulcus to ensnare the pigtail. (d ) Four weeks Iarer, the pigta il has elongated. indicati ng prog ress of the ca nine . (e) Afte r sev eral ad jus tmen ts OVl'T a 3 mon th period . the eyelet atta chme nt o f the ca n ine becomes visible. (f.K> C lin ic.l l and pe riapical views o f the (in,ll s tage o f treatment. No te cessa tion of root resorption of the incisor and the g ingival condition of th e can ine . (h,i) Idl('1",\1 a nd anterior

views I year afte r completion of treatment.

PALATALLY IMPACTED CAN INES

(Figu re 6.41 coulil1ucdl

' e)

(h)

(g)

' 46

~

1 THE ORTHODO NTIC TREATMENT OF IMPACTED TEETH

- - - - -------=-'----'-::..:. . . .--=----=---=-'-=-'---=----:..--==--=-

Ia

(b l

Figu re 6.42

(a) The initial cond ition. Ib) A pe ria pical view sho ws advanced T('S(' rp ti" n nf 11w central incisor rout a...·;f lCiall>d wi th a ca nin e ad van cing in a line close to the lo ng ilxis of tIH.' incisor. (c) Th c inciso r IV,\s extrilctt'd . an d a p plia nces are used to eru pt the can ine in to the central incisor posi tion. (Co u rtesy of Dr T Wein t>cr);t'r.)

'd

PALATALLY IMPACTED CANINES

(b) (.)

(<)

'"

I,)

w

Figu re 6.43 (a-cj Inrra-oral views of a 12-year-old gir l, I year after trauma had severely da maged the maxillary incisors. The teeth end ured severa l unsuccessful attem pts at root canal therapy, and their extraction was recom mended . Id ) The periapical t.'icw shows early oblique apical resorption of the right lateral incisor and the palata lly impacted righl canine, (e-g) Following the extractions orthodo ntic space closu re was per formed and com posite build-ups have been placed on the la tera l incisors 10 sim ulate the extracted central incisors. The remaining maxillary teeth h..we bee n moved mesially 10 close spaCC!i. (h) The peria pical view shows no addi tional root resorpt ion 01 the latera l incisor, despite it" s ubs tantial positional change. (Figure 6."3 COllfirmedl

148

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

---------~-+---------

(Figu re 6.43

cmlli um'd )

<01


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guidance theory or an anomaly of genetic origin? AI/Sit' Ort/md 65: 95-8. Becker A, Zilberma n Y (1975) A combined

fixed-remova ble approa ch to the treatme nt of impacted maxillary canines. / Clin O rthodont 9: 162-9. Becker A. Zilbe rma n Y (1978) The pala tally impacted can ine: a new ap proach to its treatment. A m / Ort/lOd 74: 422- 9. Becker A, Smith P. Behar R (l 9H1 ) The incidence of an oma lous lateral inciso rs in relation to p alatally-displaced cuspids . Allgle Ort/wd 51: 24- 9. Becker A, Koh av i 0, Zilbcrman Y ( 983) Periodontal s tatus following the alignme n t of palatally impa cted canine teeth. Am J Ortlwd 84: 332--6. Becker A, Shpack N, Shtcycr A (1996) Attachment bonding to impac ted teet h at the time of surgical exposure. Eur / Crthod 18: 457-63. Bjcrklin K, Ku rol J, Valentin J (1992) Ectopic eru pti on of maxilla ry first pe rma ne nt molars and associat ion w ith other too th and develop-

PALA TALLY IMPACTED CANIN ES

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Orthod 10: 283-95.

Brin I, Becker A, 5halhav M ( 986) Position of the maxillary permanen t canine in relati on to anomalous or m issi ng lat eral incisors: a po pulation study. Eur 1Orthod 8: 12-16.

Fearn e J, Lee RT (1988) Favourabl e sponta neous eruptio n of sev erely di splaced maxillary canines wi th associated follicu lar d isturbance. BrJ Orthod 15: 9.3-8.

Brin I, Becker A, Zilberman Y (1993a) Reso rbed lateral inciso rs ad jacent to impacted canines have normal cro wn size. Am J Orthod 104: 60-6.

Free man RS (1994) Adult trea tment with removal of all fou rs permane nt ca nines . Am J Orthod Dentoioc Ort/lOp 106: 549-54.

Brin I, Solomon Y, Zi lber man Y 0 993b) Trau ma as a possible etiolog ic factor in m axilla ry cani ne im paction. Am 1 Ort/lOli Dentoiac Ort/wp 104: 132-7. Broadbent BH (1941) O nt ogenic d eve lopment of occlu sion. Angle Orthod 1: 45. Cra mer HC (1929) Den tal survey of one thousand adu lt males: a statistical stud y correlated with physical and labora tory findings. J Am Denl Assoc 16: 122. Cresc in i A, Clauser C, G iorgett i R et al (1994) Tu nnel traction of Intreosseous impacted maxillary canines: a three-yea r periodontal follow-up. Am 1 Orthod Dentoiac Orlhop 105: 61- 72. Dachi 5F, Howe ll FV (1%1) A su rvey of 3874 routine full-mouth rad iographs. II . A stu d y of immpacted tee th. Oral Swg Oral Med Oral Path 14: 1165-9.

Ericson 5, Kurol J (1987a) Incisor resorp tion caused by ma xillary cus pids. A rad iograp hic study. Angle Orthod 57: 332-45. Ericson 5, Kur ol J (1987b) Rad iog ra phic examination of ectop ically eru pting maxillary canine s. Am J Orthod Dentoiac Ort hop 91, 483- 92. Ericson 5, Kurol J (1988a) Resorp tion of maxillary lateral incisors caused by ectopic eruption of the can ines. A clinical an d radiograp hic an alysis of pred isposing factors. Am 1 Orthod Dentofae Ort/lOp 94: 503-13. Ericson 5, Kurol J (1988b) cr d iagnosis of ectopica lly erupting maxill a ry ca nines - a case report. Eur 1Orlhod 10: 115-20. Ericso n 5, Kurol J (198&) Early trea tme nt of pa latally erupting maxillary canines by extraction of the primary canines. Eur J

Friel ES (1949) Migration of teeth. Dt'llt Rt'C 69: 74. Hitchin AD ( 956) The imp acted maxillary can ine. Br Dent J 100: 1- 12. Howard RD (1967) The u nerupted incis or. A study of the postope rati ve erup tive his tory of incisors d elaye d in the ir eru ption by supernumerary teeth. Dell! Freet Dellt Ref 17: 332-41. Ingbe r 5} (1974) Forced eruption . Part II . A me thod of treating non-restorable tee th pe riodontia! an d res torati ve considera tions. J Perioiont 45: 199-206. Jacoby H (1979) The ballista spring system for imp acted tee th . Am JOrthod 75: 143-51. Jacoby H (]983) The etiology of max illary canine impactions. Am 1 Orthod S4: 125-32. Joh nst on WO (1969) Treatment of pa latally impacted canine teeth. Am JOrthot1 56:589-%. Kohavi 0 , Becker A, Zilbe rma n V (1984a) Su rgical exposu re, orthod ontic movemen t and fina l too th position as fetors in pe riod ontal brea kd own of treated palata lly impacted canines. Am J Orttiod 185: 72- 7. Kohavi 0 , Zilberman Y, Becker A (1984b ) Peri od on tal status foll owing the alignm ent of buccall y ectop ic maxilla ry can ine teet h . Am J Or/hod 85: 78-82.

Kokich VG, Mathews Dr (1993) Su rgical and orthod ontic manageme nt of im pacted teeth. Denl cu« N Am 37: 181- 204. Korn hauser 5, Abed V, Haran 0 , Becker A (995) The resol u tion of palatally-impacted canines u sing palatal-occl usal force from a buccal auxilliary. Am 1 Orthod Dcntojac Orthop 110: 528-34. Lapp in MM (951) Practical management of

,so THE ORTHODONTIC TREATMENT OF IMPACTED TEETH --------_-.::.:=-=-==::...-===-=~::...:.:::.::: the impa cted ma xillary ca nine. Am I Orthod d isplaced canine as a de nta l anomaly of 37: 769- 78.

genetic origin. Ang/e Ort/lOd 64: 249-56.

Lewi s, PO (1971) Pre-orthod on tic su rgery in the treatment of imp acted canin es. Am I Grtnod 60: 382-97.

Peck S, Peck L, Kataja M (1995) Palatal canine d isplaceme nt: gu id ance theory or an anoma ly of genetic origin ? Sense and nonsense regarding palatal canines. Angle OrO/OO

Linda uer 5J, Rubinstein LK, Hang WM et al (1992) Can ine impaction identified early with panoramic rad iograp hs. J Am Dent Asscc 123, 91- 7. Loberg EL, Engs trom C ( 994) Thyroid ad ministration to red uce root resorption . A I/glc Urtuod 64: 395-400.

Mead SV (930) Incide nce of impacted teeth. lnternat I Orthod 16: 885-90. Miller BH (1963) The influence of congenitally missing teeth on the eruption o f the upper canine. Dent Pract Dent Rec 13: 497- 504. Mon teliu s GA (1932) Impacted teet h. A com parative study of Chi nese and Cauca sian d en tit ion s. J Dell t Res 12: 931-8.

Mossey PA, Campbell HM, Luffingh am JK 099..1) The palatal can ine and the adjacent lateral inciso r: a study of a West of Scotland pop ulation . Br J Orthod 21: 169-74. Oliver RG, Mannion ]E, Robinson JM (1989) Morph ology of the maxillary lateral incisor in cases of unilateral impaction of the maxillary canine. Br / Orthod 16: 9- 16. Or ton ns. Garvey MT, Pearson MH (1995) Extrusion of the ectopic maxillary canine using a lower removable ap pliance. Am I Ort/lOd 107: 349-59. Peck L, Peck 5, Attia Y (1993) Maxillary canine-first premola r transposition, associated d ental anomalies and genetic basis. Allg/e Grtuod 63: 99-109 . Peck 5, Peck L, Kataja M (1994) The palatally

65: 13-17.

Poumparos E, Loberg E, Engstrom C (1994) Thyroid fu nction and root resorption. Angle Orthod 64: 389-94. Power SM, Short MBE (1993) An investig atio n into the response of pa lata lly d isplaced canines to the remov al of deciduou s canines an d an assessment of factors contrib uti ng to favou rable eruption. Br I Onhod 20: 215-23.

Proffit WR (]992) Contemporary Orthodontics. Mosby Year Book, St Louis. Stern N, Becker A (1980) Forced eruption: biological and clinical consid era tions . ] Oral Rehab 7: 395--402. Takahama Y, Aiyama Y (1982) Maxillary canine impaction as a possible m icroform of d eft lip and palate. Eur I OrtllOd 4: 275-7. Thilander B, Jacobson SO (1968) Local factors in imp action of maxillary canines. Acta Odont Scond 26: 145- 68.

Vanarsda ll RL, Corn H (1977) Soft-tissue manage ment of labially po sition ed un eru pted teeth. Am I Orthod 72: 53-64 . von de r Heydt K (1975) The su rgical uncovering an d or thod ontic pos itioning of u nerupted maxillary canines. Am I Orthod 68: 256-76. Zilberman Y, Coh en B, Becker A (1990) Familia l trends in pa latal cani nes, anoma lous lateral incisors and relat ed pheno mena. Eur ] Ontiodonr 12: 135-9.

7 OTHER SINGLE TEETH

CONTENTS • Bucc all v impact ed canines • Mandi bu lar can ines • Mandibu lar second premolars • Maxillary second premolars • Maxillary first m olars • Mandibu lar second molars • Impaction and cr own resorptio n • Infraocclusion 01 permanent teeth

• Dentigerous cys ts

Aside from the third molars. the maxillar y canines and central incisors are the principal teeth that may become impacted , but. from time to time, othe r teeth may also be a ffected . For so me of these tee th, fam iliar pa ttern s emerge, typica lly affecting the same tooth and with the same aetiology in ma ny of the cases. In others, u nu su al pa thology is involved , which may affect any too th or gro up of teeth and is therefore quite unspecific. Nevertheless, even with a wide ly heterogeneous grou p, tren d s may be recognized an d treatmen t p rot ocols may be suggested to cover a good p roportion of th em .

BUCCALLY IMPACTED MAXILLARY CANINES As we have poin ted ou t in Cha pt er 6, crowding is the p rin cipa l cause of buc cally d isp laced cani nes, and the scenario by which it occu rs was d escribed there. In a small number of cases, the canine 's eru p tion is d elayed or interru pted , and remains in its very pa lpable an d uneru pted buccal position indcfinitely. In others, it may erupt hig he r up in the

area of the sulcus oral mucosa, whic h creates a poor gingiva l attachment. From the periodontal po int of view, havin g on ly thin oral epithe lium cove ring the root leaves the patient with a delicate and eas ily traumatized atta chment ap parat us. Surgical and or thodontic tre atment were described in Cha pte r 3 to resolve th e problem. Occasion ally, one may sec a pa tien t in wh om the uneru pted canine is on the buccal side of the al veolus, with its crow n very high an d strongly mesiall y d isplaced , labial to the later al and cen tral incisor roo t apices . Although the se art' u sually palpable, the unu sua l height of the tooth in the sulc us may lead to the clinical diagnosis being missed . Beca use of the ob liqu e angle at whi ch th e X-ray con e is directed , the periapical radiographs will produce a mislead ing pict ur e that sho ws the superi mposition {If the ecto pic too th more inferiorl y depicted on the roo t of the lateral incisor, giv ing i t the ap pearance of its being palata lly d isp laced . Surgical access is good , bu t the ability to p rovid e a satisf actory or thod ont ic s trategy 10 red uce the impactio n is poo r. This is becaus e the high buccal canine tooth must be brough t inferiorly and bu ccally , in a manner that

152 _ _---'

THE ORTHODONTIC TREATMEN T OF IMPACTED TEETH ---'::...:--'--:.:.::-=-:::.::.---'--'--=----'--'----'--.::.:.:=-=~

,.,

lb)

(d

(d '

Figu re 7.1 (<1, b) Clinica l views show ing an over-re tained deciduous ri ght m a xillar y ca nine. Noll' the labi al a nd dis tal tipping of thl:'

right latera l incb or crown a nd pa lal,,1 root pos ition. (c) Ante rior occlusal view sho w ing s u perimposition of c
OTHER SINGLE TEETH (Figure 7.1

((Jlrtin llt"d)

(1.')

'.'

(hl

circumvents the roo t of th e adjacen t incisor. This wou ld involve its being d raw n in a sem icircular flan king movement, a round the lateral incisor root, in an area w her e the alveolar bone is too nar row to allow one root to pass by another. As the canine is moved labially, the labial plate of bone thickens and also remodels lab ially. However, it does so to a lesser exten t than the den tal movement, until the root of the tooth no longer has a labial pla te a nd is covered only with g ingiva l soft tissu e. The prospec ts for mu co-gingival su rgery, per formed at the time of exposure, are very limited for the high bu ccal can ine,

and so we mus t expect to see a lon g clinical crown and a poor p rog nosis for the tooth in this po sition (Kohavi et al, 1984). As a general rule, the mo re seriously d isplaced buccal canines of this type arc best extracted and , as far as possible, the d ecidu ous canine left in place, pre ferably with its crown prosth etically enlarged . If the deci d uous canine has a poo r prognosis, an earl y decision regarding space closure shou ld be mad e. Where ap prop riate, con troll ed orthodontic space closure may then be carried out, with or without a compensating extraction on the oppo site sid e (Fig. 7.1).

THE ORTHODONTIC TRE ATMENT OF IMPACTED TEETH

~::..:::~======~==='__

154

MANDIBULAR CA NINES Since the y ar c very infreq uent, little may be found in the den ial lite ra tur e abou t the impaction of mand ibul ar permanent canines, aside from the od d case report. They seem to occur mainly in associ ation with an u nreso rbed deciduous pred ecessor; however, they are sometimes st't' n lon g a fter the d ecid uous tooth has shed norm ally a nd there is a relalive shor tage of space in the im mediat e area. They may also be foun d to be prese nt as the TI.'SUIt of an obstruction, suc h as a supernumerary tooth or odontome . Often located on the lingu al side of the alveolar process , they will appear as ,'I palpable hard swelling u nder the lingual mucosa, although they may equally be found buccally ectopic or in the genera lline of the arch . The periapical rad iograph will most often p rovide adequa te qualitative information regardi ng the ma ndibular cani ne, un less it is very deeply displaced . This is because it ma y not be possible to insert the film suffic iently deeply into the lingua l s ulcus. In these cases, an anteriorly rota ted lateral obliqu e film ma y pr ovide a better view of the too th. Since these two views are tak en close to the horizo ntal plane, a tr ue occlusal view will be need ed to accu ratel y localize the too th. Just occasionally, a single mandibular canine ma y be grossly di sp laced , mesially an d dee p in the basa l area of the mand ible. Its axial or ient ation is hori zon tal, with the crown close to or actu ally crossing the mid line sym physis (Fig. 7.2). In this type of cas e, extraction will be the only pra ctical line of treatment available. Gi ven the presence of the roo ts of adj acent teeth lrnmcdi atcly superior to it and the narrow dimensions of the mand ible, th ere is no room for su ccessful orthodontic ma noevre, unlike a similar a nom aly occu rring in the maxilla ry arch. For mo st impacted mandibular canines, however, a carefu l radiographic evaluation \v iIl indi cate a reaso na ble p rospect for alignment (Fig. 7.3). In line w ith the ge ne ral principlcs tha t were sot ou t in Ch apter 4, an or thod ontic applia nce is placed an d s pace is prepared in the ar ch 10 accomodate the tooth before its expos ure is undertaken (Fig. 7.4).

Figure 7.2 The crown of the horizontally im pacted right man d ibula r can ine ove rlies the rooe of the erupte-d ma ndibular canine of the opposi te side. (Co urtt.'Sy of Dr T Wei nlx-rgc r->

The initial levelling and space-opening archwires are rep laced by a heavier base arch , which will provide the ancho rage for the des ired traction. A measu red piece of stainless steel tubing is thread ed ove r the arc hwire and liga ted between the first p remo lar an d lateral inciso r to actas a spac e mainta iner. A lingually d isp laced canine is usu ally best exposed , an attach ment bonded to its buccal aspect an d the wound fully closed with th e resuturcd flap , un less the tooth is very su per~ ficial. In this way , traction fro m th e attachment d irect to th e labial archwire may provid e the two directiona l components of force, i.c. bu ccal and extrusive, that are needed to bri ng it to its place. The wire liga ture pigtail, which was tied to the bonded attachmen t at the time of surgery, is rolled downwards to furm a loo p, close to the rcsutured gingival tissues. A ll clastic chain is p laced across the span bet we en first p remolar and lateral incisor, an d its midd le portion is stretched downwards wit h a hac mostat or ligature d irec tor and ensnared in the ro lled down p igta il. This p rov ides an eas ily mea surable, light and ver tically d irected force on the impacted too th, with a wide ra nge o f action.

OTHER SINGLE TEETH

C,)

lb)

Cd

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Figure 7.3 (a) The left mandibula r canine h,lS o.... -n gwssly d is rl ,Kl'l.i di stall y a nd in fer iorl y, because o f an od on tomc, an d ts in clos e ,1sSilCiation w ith the low er bord er o f th e ma ndible. (h) A true occlu sal v iew o f th e Cil n ine/ p r('molar ar ea. (c) After alig nment ,111d space opening, surg ical re mova l o f ove r-reta ined d eciduo us tooth a nd od on tom c has pt'nn ilt l'd attach ment p lacement. (d) Ra p id im p rov eme nt in positiun h,lS occu rr ed. Note the deleterious d flx ts o n a rch for m a nd m id line d ue to use of base arch o f ina d equate siz e. (e) A pe riapica l \';ew in the latter stages of resolu tio n. (Cou rtesy o f Dr R Rcmano.)

I,)

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

156

(b )

(.J

Fig ure 7.4 (a) Expos ure of rig ht man d ibular ca nine w ith dentigero us cyst. Eyelet attachmen t in place. (b) Fully closed an d healed tissue. xote the use of ve rtical elasti c in latter stages, to pr event bite opening. (c) Fina l d etai ling of roo t positi on .

'd Transposition A spe cia l case ma y be made for the buccally d isplaced mand ib ular ca nine, transposed mesially to the lat eral incisor. This is no t a n uncommon form of transposition. The crow n of the canine will need to be moved buccal lv, in order to sidestep the la tera l incisor root, before being moved towards the archwirc.

As with the parallel situation in relation to the buccall y displaced maxillary canine, tha t w e hove described abov e, the orthodontic and periodontic p rognoses of treatment for these teet h dete riora tes in inverse relation to the amount an d type of mechanothe rapy us ed . For thes e tee th. the re re ma in three altern a-

tive lines of treatment for the non-crowded The clinician may

C,1St'.

(a) extra ct the ca nine, lea vi ng the deciduous ca nin e in its place, provided its root is of reasonabl e length and progn osis; (b ) extract the lat era l incisor and align the ca nine in its place, leaving the de ciduous canine in p lace; (c) de libera tely align the two teeth in a tr a nsposed rela tions hip, which, in the mandibular arch, may offer the op timal solution (Bre zn lak et al, 1993). In the eve nt of cro w d ing, ex tra ction o f the deciduous ca nine and th e perma ne nt cani ne, or of the d eciduous ca nine a nd the adjacen t pe rmanen t incisor, is us ually most approp ria te. The space provid ed may then be used for the relief of crow d ing, as pa rt o f an orthod ontic trea tme nt programme for other aspects of the malocclu sion .

157

OTHERSINGLE TEETH

MAN DIBULAR SECOND PREMOLA RS

Crowding and space loss Perhaps the most common cause of impaction of the second mand ibular premolar is the ea rly extraction of its deciduous predecessor, although this has become less frequent with the d ecline of caries in the weste rn world. U this loss occurs in the very young patient, u p to the ea rly mixed dentition stage, there will be consid era ble tipping and d rifting of the first mola r in a mesial direction. Add itionally, there will be a degree of distal dri fting of the first d ecid uous mola r of the sam e side, such that the space for the second premolar may be totally elimin ated, before it has the chance to eru p t. The resu lt will be that . this successional tooth will be blocked from erupting into th e dental arch. Its early developmental pos ition being slightly lingual to the line of the arch and its being prevent ed from develo ping superiorly in the no rm al man ner, it will either move mor e lingually and eru p t on the lingual side, or it may remain impa cted and beneath th e 'pitched roof ' formed by the two ad jacen t erupted an d tilted teeth. The radio graphic method for these cases is very sim ilar to that described for mand ibu lar cani ne teeth. The periapical film is used to p rovide d etail, bu t is also a true horizon tal view in this area. Therefore it may be su pplemented by an OCc1US.ll view , to ena ble accurate localiz ation . Space has to be pro vid ed for this tooth, whi ch is us ually achieved by the extraction of the ad jacent prem olar, wit hin th e context of an overa ll extraction pro gramme aimed at reso lving existing cro wd ing in the entire de ntition. Alternatively, the drifted teeth must be reslted in their ideal positions, using a fixed orthodo ntic app liance, wit h a coil spring com pressed between the first molar an d first p remola r bracket s. Th is may require that the an cho rage be supported by an extra-oral headgear in the opposing jaw, throu gh the agency of interm axilla ry (Class Ill) elastics, to prevent mesial migra tion of an terior tee th. By w hichever method spa ce is made, the tooth will normally erupt with consid erable speed , witho ut fur ther assistance.

A third alternati ve, of course, is to extra ct the impacted toot h and align the others into wha tever space rema ins, usually together with ext raction s made in each of the other d ent al qu ad rants. From the pe riodontal po int of view, excision of un erupt ed mand ibular second p rem olar s may leave a marked bony defect in the area, even afte r the adjacent tee th have been fu lly u prtghted .

Abnormal premolar orientation The second deciduous mola r of the lo wer jaw has much to answer for in relat ion to the noneru pti on of its permanent successo r, not merely w hen it is prematurely lost owing to the ravages of caries, but also when there is a p rolonged p resence. The second premolar tooth germ is not always in its ideal developmental pos ition , d irectly between the mesial and di stal roots o f the d ecid uous molar. Ind eed . an abnorm al angula tion or location seems to be quile freq uen t. The premolar may often be tip ped more d istally and initiating resor ption of only the d istal roo t, leaving the mes ial roo t of the deciduous molar largely unrcsorbcd. This w ill lead to over- reten tion of the d eciduous tooth - often d espi te the comp lete d isappearance of th e d istal roo t and much of the d entine from within the cro wn. A periapic al rad iograph will show the p rem olar very superiorly positioned , alm ost inside the d istal part of the cro wn of the deciduous tooth , bu t a long and thin spicu le of the mesial root remains, gr imly resistin g exfoliation. A peralIel scenar io may occur with a resorption of th e mesial root d ue tomesial tilt of the second premolar from early on in its d evelopment, although it seems to enjoy a lower frequency. In either of these cases. for as long as the degree of tilti ng is rela tively slight and the tooth is relatively high up in th e alveolu s, the extrac tion o f the deciduous tooth will usually suffice to achieve the rap id and trou blefree eruption of the p remolar too th. Space is nev er a problem in these cases, since the second p remolar has a sma ller mes io-d istal crown width than its healthy pred ec essor.

158

-

-

- - - - --

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- --

A premolar too th that has a st ronger distal tilt is usually situated more apically. and the

d istal-occl usal aspect of its crown is in close relation with the mes ial as pect of the mesial root of the first permanent molar
---'--

-

-

---'----'--

classically a buccal and lingu al bar may be soldered to two bands to form a simplified fixed brid ge, which is then cemented to these teeth. A sing le rig id bar, with a mesh p ad a t each extre mity, may be bonded to the buccal surfa ce of first molar and first pre molar. and is a fairly good alterna tive, provided that it is well clear of the occlus ion, althou gh, even in th is situation, it may still be disp laced by occlusa l forces transferred by bu lky and hard food s. At s urgery, the impacted premolar tooth is exposed in its mesial and occlusal aspects only, and , wh ere possible, an eyelet should be

",

Figure 7.S

(.1) A late d eveloping left second premolar, horizontally orie nted. (b) A year lat er, the tooth has moved distally to OVt·rl.lp the mesia l root of the first pe rm.l 0t'n t molar. (c) Extra rtion reveals some resorption of the mesial roo t of the molar. (Cou rtesy of Profes so r Y Zilbt.-ml
,
OTHERSINGLE TEETH

hand ed to this area o f the cro wn of the tooth. Since the toot h is fairly dee p d own , the flap is comp letely su tured hack in to its pl ace, and the stainless steel liga tu re wire pigtail, tied to the bonded eyelet, becomes the means o f applying force to the un erupted tooth. This is app lied from an elas tic module stretched between a hook on the fixed hand o f each of the two erupted teeth, parallel to and overlying the rigid bar. The greater the d egree of movem ent req uired , the more su bstantia l mu st be the a nchor base, and, in thes e instances, a fixed ling ual arch to the oppos ite molar is preferable. This area d oes not pro vid e easy access to permit acid-e tch bonding
(,)

(bJ

(d

Infraoccluded second dec iduous molars

Fig ure 7.6

These ar e a relatively common occu rrence, and are know n to shed q uite normally in

Seria l pe riap ica l vi.,w s n f ,1 f,l il•-d attem pt to bon d a n Ed ge wise br acket to an ina dequately develo ped sec on d mandibula r premola r. (Co ur tesy of Dr D U,lr.Hy .l

160

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - - - - -- -- - - - - - - - - - - - - -

Ibl

'd

'd)

Figure 7.7 (.ll Panoramic view of a case co m plicated by maxillary im pa cted canines, I'lll.~d c\'cl"ping man dibul,tr M'Cund pr",mOlil f5 MId total ~ p,lce loss on till' It'ft skit'. (b) A periapical view show s bon ding uf an attac hment tu the right second pr emola r W,I, achieved only aftt'T wid e t' XpOSUTl' , (c) A similar follow -up r,ldiugr,lph show s improv emen t in till' position of the tooth, but rr estal bone height is deficient. (J ) A pa nora mic view Llf the final slages of treatme nt clearly shows the

reduced periodon tal prognosis of th e r ig h t mandi bu lar sec ond premolar. (Courtesy of D r L Rothst ein.)

most cast's, w ith only a relatively minor delay in the ir ex folia tion time (Kurol, 1984; Kurol an d Thil a nd er, 1984). Neve r theless, w hen the infraocclu sion is very marked , a n extre me verti cal d is placem en t of the a pically p laced successor w ill be present. Indeed, the apex of the roo t of this developing tooth may even

ca use a pa lpa ble prominence in the othe rwise smooth profile of the lowe r border of the ma nd ible (Bec ker a nd Sh ocha t, 1982). In these cases, it is qu ite im p ractical to atte m p t to bo nd a n a tta chment to th ese grossly di splaced premolar too th. Fortunately, with infraocduded tee th,

OTHER SINGLE TEETH

actual spa ce loss within the mandi bu lar de ntal arch is very minima l Wecker and KarneiR'em , 1992a,b; Becker et al, 1992) an d this rarel y pro vides a p roblem within the ort hod on tic strategy. However, once the infraooelu ded too th has been rem oved , space loss may be q uite rapid, a nd a space maintainer should be placed . No atte m pt shou ld be ma de in the firs t ins tance to uncover the very d eeply p laced p remolar, but , following the removal of the d ecid uous too th, the pa tien t shou ld be followed u p over a long pe riod of time, with an occasional pe riapical ra di og raph ta ken to check for eruption progress (Fig. 7.8). Few clinicians have record ed the ir experience with these ext reme cases in the literature, and opinions are strongly influenced by single case treatmen ts. Howeve r, there would appear to be some merit to a 'walt-and -see' policy and some reason for optimism in these very special circumstances. lnfraocclu ded deciduou s teeth are associated with a lack of alveolar bo ne height in the immed iate area. The height from the inferior bord er of the mandible to the occlusal table is significantly reduced when co mpa red with a nor mal unaffected opposit e side (Becker and Karnei R'em, 1992b). Extrac tion of the infracccluded too th initially leads to healing and bone reo rganiza tion, which, in the ab sence of permanent teeth , will not increase the vertical heigh t of the body of the mand ible in that area. If a permanent tooth is present and the n begins to erupt, al veola r bon e d evelopmen t occurs before an d im med iately following the eruption , and the ver tical bony d eficiency is eve ntually mad e good . However. this m ay be pa rtial only, and a lateral open bite may sometimes p ersist (Fig. 7.9).

MAXILL A RY SECOND PREMOLARS The m ost common reason w hy these teeth become impacted , as with the mand ibular second prem olar, is related to s pace loss in the d en tal ar ch, follo wing the early extr action

of the deciduous secon d mo lar an d the drifting of the two adja cent tee th, particularly th e first p erm an en t molar. It is also tru e that mesial movemen t of the first permane nt molar in the maxill a is mo re rapid than in the ma ndible, it more completely closes off the space, and it does so even in the late m ixed dentition s tage. Therefore , when s pace has been lost, the maxilla ry second pr em olar is mos t o ften to be see n develop ing with its roo t in the line of the arch, and with its crown deflected palatally and pa lpable on the palatal side o f the alveolar process. Infraocclusio n so metimes affec ts the maxillary deciduous second molar too, and , when thi s is in its severest fonn (Fig . 7.10), the successi onal seco nd premola r seems frequen tly to be d isp laced both palatally and more m esially th an usual. It is ofte n ro tated and located high in the maxilla, beyond the area ,... he re it may be expected to be palpable. Because of the oblique angle of the X-ray tube in periapical radiog raphy o f this area, the palatally tip ped an d unerupted second prem olar w ill be viewed almost throug h the long axis, and will be depicted on the film as an ellipse. Thi s bein g the case, it is probab le tha t fu rthe r Xcray films are unnecessa ry, par ticu larly if the too th is palpab le in . the palata l area. Wh ile the con ve nt iona l (oblique) occlusa l film or a second , laterall y shi fted , pe riapical film will offer the opportunity to ad d three-d imensional infor mati on, the true ve rtex view would be more d ec isive. In gene ral, and quit e regard less of the aetiolog y, second pr emolars in the max illary arch will erupt spontaneo us ly, and, as this hap pen s, th ey also sp ont an eously resolve their palatal d isplacement. The only essent ial requirement is that there be ad equate space in the arch and that this s pace be maintained (Fig. 7.lOb). Most often, the second premolar does not need to hav e an attachmen t on it, nor is it usu all y necessary to eve n expose it. Unlike othe r teeth, the re a ppears to be littl e benefit in go ing through the elabora te or thodontic and su rgica l prepara tions that we hav e descri bed in relation to incisor an d canine tee th . Little harm will be inflicted by the exposu re and bonding of a n attachme nt, but the exercise will almost a lways be sh own to

162

THE ORTHODONTIC TAEATMENT OF IMPACTED TEETH

(bl

(d

f igu re 7.8

A ",eTit'S of peri a pical views of an imp..KI..'\1 ",,,·a'n<.l premo lar, displaced in feriorly by an inlraocclu d..-d d eci d uous second mo lar. (a) the initial vi..,w; (h) after SP.l("(, reopening: (c) after extr actio n a nd Sp.1U' maintainer plac..-men f Id ) s po ntaneous imprt'\'em"'nl; (e) the eru pted tee thNo other Orlhochmlic prtlO.-dun... Worn.' initiated. (Court..""y of Professor Y Zilberman.)

Ie)

OTHER SINGLE TEETH

(01)

163

(b )

Fig u re 7.9 (a,b) Intra..... ral vie ws o f a case in which the left mand ibula r first dnd second d ecid u ous mo lars h'ld been infraoc.. elud ed an d we re extracted 18 months earlier. Eruption W ilS initi a lly r,l pid, bu t inmm plele a nd furt he r cru pnon has not occurred. (c) Pa noramic view of ca....•. (Cou rt....y of Dr M Barvcl.)

(d

(,)

(b)

Fig ur e 7.10

(a) Characteristic extreme tipping ...f the teeth .1dj.:lCt'nt to a n infraoccludcd maxillary d ecid uous seco nd molar. The St.'C. o nd p remola r is displaced su peri o rly an d mt'Si.llly, exh ibiting d ma rked distal ...ric nta tio n. Ib) Spare r~l!>,l i ning and main tena nce , with extracti o n o f the infraooduded d eci d uou s mo la r. h..1S res ulted in s p...n taeeous conccnon of tooth posinon. Eruption is im minent.

-.::.:::..:=:.::==-.::.=======-=::.:

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

164

(., (bl

(01

(d '

Fig ure 7.11 (a) Incomplete eru ptio n of the ma xillar y first per manen t molar. due to a bnormal angulation of its lo ng a xis. It has become impacted bClll"llh the di stal bulbosily of the d ecid uous second molar. (b) The removable appliance ca rries flvc retention clasp s a nd a palatal 'fing er' spring that trave rses th.. occlusal surface ()f the partially eru pted firs t mol a r. An ac rylic bllll nn is placed on thai portio n of

the spring that cernes into contact with the occlusal SUTface of the first mola r. (c) The incom plet ely sea ted app liance s hows the s pring in its p assiv e mode, d ista l to the molar. (d) The patie nt has brought the spri ng mesially, prior to fu lly sealing the applia nce. (e) The molar is disimpacted and in fu ll (Class II) occlusion . (I, g) Lateral oblique extra-oral films before and after treatment show the ad vanced resorpti on of the second decid uous molar. (e

OTHER SINGLE TEETH

165

(Figur e 7.11 cOlrlimlrd J

(g )

have been su perfluous, excep t in the most excep tion al di sp lacements.

MAXILLARY FIRST MOLARS In the early mixed dentition, one may occasionally see the erupting ma xillary molars become cau ght by the d istal bulbosity of the ad jacent deciduou s second molar (Fig. 7.11). This is usually an ea rly sign of crowd in g of the dentition, although it may simply be due to an abno rmal mesial tilt of the first molar. Clinically, the essential d iagnostic criterion is that the margin al ridg es of th e two adjacent teeth arc at different levels, with tha t of the decid uous tooth being more ocd usally p laced . In the more severe cases, the mesial marginal ridge of the perm anent mola r is unseen, benea th the area of the di stal e Ej of the deciduous too th. At best, the di sta l cusps may be in occlusion w ith the mand ibular mola rs, bu t usu ally th e imp action prevents adequa te eruption for this to occu r. Occasionally, the perma nent mola r is cornpletely prevented from eru pting, and d oes no t break through the mu cosa.

A peria pical or pa noramic radiograph of the area will usually show mo st or all of the d istal roo t o f th e d ecid uous second mo lar to have been reso rbed and the general long axis and pa th of eruption of the permanent tooth to be tipped too far mesially (Fig. 7.11). To leave a partially erupted molar tooth without treatment is to invite caries in the large stagnation area th at has been creat ed between it and the dec iduou s mola r, which serves to compound the existing po ten tial gingival/p ulpal p rob lem in the area of contact. In general, the mesial root of th e decid uou s secon d molar remains in tact, to retain this too th in its p lace. If the deciduous second molar is shed prematurely or extracted , the permanent molar w ill move rapidly forwards, significantly closing off the space vacated by the lost tooth. within a few sho rt months. The tooth also erupts occlusally at the sam e time, and its moveme nt has a significan t forwa rd translalion component, in ad d ition to its mesial tipp ing component. This being so, orthodontic treatment, whose aim is to tip the tooth back to its ideal pos ition after full eruption, wiII generate an excessive d istal tip to the molar . which will leave the roots too far mesially. Secondly,

166

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - - - - -- - - - - -- -- - - - -- - the achieved space w ill require to be maintained for around 5 years, until all the succcssional teeth have erupted. Regardless of how well designed and constructed the proposed spacc-ma tntatrung device may be. its placement in a 7- Of 8-year-old patien t must provid e some concern vi s-a-vis its deleterious effect on the lon g-ter m prognosis of the first molar. Man y original ideas a nd gadgets ha ve been s uggested to d isim pac t the ectopic firs t mola r

from beneath the distal bulbosity of the d eciduous second molar, the sim p lest of

which has been to use an elastic separating ring or othe r form of orthodontic separator, whic h are nor mally USl..U to create spaces prior 10 b anding molars. These may be successful in some of the very mild cases, although what frequently ha ppens is that a space between the tee th is prod uced w ithin a week or so a fter placemen t of the ring. The clas tic ring is then rem oved to allow the per ma nent tooth to eru pt occlusally. In many cases, the molar tips r ight back in to its p re viously im p acted position, an d no thing will have been ach ieved. This type of rela pse may occu r \v-ith any method that is only concerned w ith tip ping the tooth d istally, w ithout p rovid ing for ,1 retentio n pe riod. The ret en tion period is in tended to permit ad ditional eruption of th e tooth, while preventing rclmpactton . A fixed de vice has se ver al apparent inherent ad va nta ges , bu t it mu st be remembered that the patient is a young chil d, who may be relati vely unwilling to cooperate in its con struction. Additionally, most orthodontis ts do not hav e a selec tion of preformed deciduou s secon d molar bands, a nd the placem ent of a band on the perma nent molar is im possible in all bu t th e sim plest of cases. Suitable condition s for com po site bon ding a rc also e xce ption ally d ifficu lt to a ttain in th e mo lar area of such a young child, and results a re u nr eliable. Nevertheless, appliances have been designN based on a fixed band on the deciduous second molar only, or o n an add itional fixed ba nd on the second d ecid uou s molar of the opposite s ide, through the ag en cy of a sol d er ed palatal ar ch. A sold ered sp ring is formed on a model. w h ich fits in to the mo st conven ien t and deepe st occlusa l pit o f the

ec topic mola r and is activa ted prior to cementa tion of th e applia nce (Proffit, 1992). It is quite difficult to read ju st this spring in the mou th, which mi'ly make this a one-time-activati on app liance, unless the w ho le cementatio n process is repeated . At first gla nce , a removable appliance seems ina ppro p ria te, since there aplX'ars to be no ''''ay o f passing a cantilever spring across the in ter proximal a rea , mesial to the too th, to apply the necesS
OTHER SINGLE TEETH

view . to ext raction a nd re place me nt by a n a rt ificia l sp ace main tainer. To find the parallel s itua tion in the mand ibular arch is very ra re. Ho w ever. management wou ld be very similar to w hat has been described for the maxillary first molar.

MANDIBULAR SECOND MOLARS Im pa ction of the ma nd ibu la r second mo lar is uncommon, but, when it occu rs, it is very sim ilar in its appearance to that so ffl..-quently . associated wi th third mo la rs. Almost inva riably, the Im paction is du e to a mes ial inclination o f the tooth, w hich bri ngs it in to con tact with the d istill side of the firs t molar , below its bulbosi cy an d d ose to the cervical a rea. Th is, too, is p roba bly a sig n of a sho rt arch leng th an d retromola r cro wd ing. Unlike the maxillary first molar , the mesially im pac ted ma nd ibu lar second molar is frequ en tly unerupted. a nd us ua lly comes to lig ht in a rou tine dental examination, when it shows up on the bite-wing rad iographs. Ho w ever, this view cannot replace the periapical film, a lateral obliq ue extra -oral view or a panoramic scan, w hich will s ho w d etails of the tooth, from cro w n to apex, a nd its relations hip w ith the unerupted third mola r. The too th ma y also ha ve a bu ccal or ling ua l tilt, wh ich will ge ne rally be revealed by palpatio n, alt hough a n occl usal view w ill ser ve to co nfir m.

Local treatment If treatment is to be pe rfo rm ed on ,1 local bas is only. in the absence of any other form of concurrent malocclus ion, then the firs t part of the trea tme nt in volves the s urgica l removal o f the overlying m UCOS
jus t tw o or three teeth. w hich may serious ly undermine the an chorage. Id eally, teeth o n bo th sides of the mandibular den tal a rch should be included in the anchorage unit tMa joura u a nd Norton, ]995), in order to prevent u nwanted movement of other tl,t..th in the a rch , pa rt icularly to eliminat e the possib le occu rre nce of lower inciso r cr owding . A min imum suggested a nchorage unit s hou ld includ e fixed ba nd s on bo th first molars, joined by a sold e red lingu al a rch, a nd orthodontic bracke ts on the p remola rs of the a ffected sid e. The active element may be constructe..d in one of fou r way s: (a) A free-slid ing sectional w ire is s lotted into the bracket s a nd the mol ar tu be on the affecte d side, activa ted by an elastic modu le, w ith its d istal end la tching o n to a s ma ll a ttachme nt on the buccal or occlusal sid e of the im pacted tooth . (b) A s imila r method is used , em ploying ,1 compressed coil s pring (Fig. 7.12). (c) A la rge and stiff open loop o f rec ta ngu la r wire is placed in the d istal end o f a bu ccal tube or wide Sia mese bracket on the mo la r and designed to widely e ncircle the impacted tooth. w ith a small heli x a t its ex tremity. By tying a stain less steel ligature be tween a bo nded evclet o r button on the OCd US.1l of this too th an d the small ter m inal loo p, d istal p ressure is brought to bea r on the im pacted mo lar (Ma joura u a nd Norton , 19(5). (d) A co mplete ro und w ire loo p w ith a d is tal helix may be slott ed int o buccal and lin gual horizontal tu bes on the mo la r band. Activa tion is made as for (c ) by tying a s teel ligat ure be tween th e helix an d a n attachment on the tooth (Fig. 7.13).

Treatment as part of a comp rehensive orthodontic treatment p lan For most cases, some form of overal l ma locclu sion is presen t, for which trea tme nt needs to be prescribed . The resolution of the impacted tooth shou ld be in tegra ted in to the general trea tmen t plan .

'68

THE ORTHODO NTIC TREATMENT OF IMPACTED TEETH

- - - - - - - - -- - -- - - -- - - - - -

i,'

ib'

ie)

(dl

Figu re 7.12 (a,b ) A roil ~pring ts threilJt...J on to ... sectional arc hwjTt', w hich is slottt.'d inlo th e distalend of a buccal tube on the first mol ar band. The d b l,11 end of th e w in.' carries a we ld ed stop o r cross-piece, wh ich permits com p ression or the roil s pring .1g,li nst ,I hutto" o r eyele t attachment on the second molar. A lingual arch ,In ,l fully bracketed appliance is present fur additional anchorage. (c.d) Panoramic views before and ...Iter trealmen\.

OTHER SINGLE TEETH

If th e overall malocclusio n requ ires extraction, considera tion should be given to the ex traction of this im pa cted too th, toget her with appropria te ba la ncing an d co m pcnsating extrac tions in the othe r quad ra nts of th e mouth (Wilson, 1966; Staggers, 1990; Richa rdson an d Richardson , 1993). This is not a frequent extraction of choice, but, under the circu mstances of a very d ifficu lt im paction, it should be considered . Th is ena bles the d ispersa l of m ild cro w d ing to be effected w ith grea t facility, w ithout the need for the extens ive root u prighting mo vem e n ts tha t a rc seen w ith p re molar extract ions. HO\\'ever, the o rt ho dontist will be countin g on the fa vou rab le eruption of the third molars (w hic h w iII be sig n ifican tly ea rlie r in these cases) and thei r spontaneous alignment. Shou ld th is not occur, a fu rth er pe riod of trea tment w ill need to be init ia ted in th e young adult stag e, ai med a t u prigh ting the mesial ly li pped th ird mo lars, from a pos ition tha t ma y be reminiscen t o f the initial pos itio n of the ex trac ted second molar! In this s itua tion, the a bo ve proced ures ma y be a p p lied to bring about third -m ola r uprighting, in exactly the sa me wa y as w ith seco nd mo la rs . Perhaps th e best wa y to visualize the po te nti al influence of the extra ction of d iffere nt groups of teeth , is on the panora mic rad iog ra p h. With a mesially tip ped second mola r in a n ex tracti on case, the loss of a first or second prem ola r e nd the mes ial move me nt o f the first mo la r may ofte n free the too th to er upt, but th e tipping will re main, an d may even bec ome worse, w ith the toot h a p pea ring to 'fall (J ilt on its face' . Uprighting will th en need to be u nd erta ken , using the existing m ulti bracketed a ppliances . Where the mandibula r a rch is well alig ned or sligh tly cro wd ed, me sial to the fir st mola rs, bu t the re is a Cla ss 11 rela tion sh ip or crowd ing of the maxilla ry de n tit ion, all the uppe r an d the pos te rior lo wer teeth w ill proba bly need d is tal mo veme nt, ra the r tha n ext rac tio n. This w ill genera lly be pe rformed w ith the use o f a n ext ra-oral hea dgea r, to move the maxillary tee th d istall y a nd thus to provide the s pace necessa ry for the alignment of the max illa ry teeth. If Class III

in te rma xilla ry elastics, su pported by the head gea r, a rc used aga inst a lo we r applia nce, whose purpose is to mo ve the ma ndibular mo lars distall y, the force w ill be tra nsfer red through in ter proximal contacts to the second mola rs, which wiII initially resist the movement. H owever, if the seco nd molar is tilted less tha n 45° a nd is in con tac t w ith the d ista l of the first molar crown, a bove the eEl a rea, the tooth will ultim a telv t ip d ist all y a nd uprig h t, w hile the first mola r w ill itself be tipped dis ta lly. O nce the secon d molars ha ve erupted, the d ts talizin g force is d iscon tinued , an d the first mola r w ill the n spontaneou sly tip forward until residu al space has been closed off.

IMPAC TION AN D CROW N RESORPTION In teet h tha t a rc u nerupted over ma ny yea rs, the ou te r e na mel epitheliu m ma y occ asionally brea k down, a nd d irect co ntac t between bone a nd e na mel occu rs. In time, th is mav lead to resorption o f the e na mel, often wit h the la ying d own of bone in the resorption lacunae. Any tooth may be affec ted, although it te nds to occu r in adu lts whose d en titi on is established and w he re the une ru pted too th m ay ha ve been re placed p rosthe tically. Ra rely, it may occ ur in a yo u ng pe rson, for whom there is a relat ively greate r im po rta nce in b ringing the tooth in to the d en tal a rc h. The firs t clue to its ex istence is seen rad iog ra phicall y, w ith d ifficulty in d is ting uis hing the outline of the dental follicle on a radiograph . Thi s usua lly s ig nifies the init ia tion of a replaceme nt resor p tion p rocess of the en a mel, w ith bone bein g la id d own in tho area. In its more ndvnnccd stages, th e radiogra phic appearance of the tooth shows a loss of the s ha rp outlin e of the crown a nd , la ter s till, a reductio n in the radiopacity of the crown (Fig . 6.11), associated w ith a s tea dy decalcifica tion of the e na mel (Blackw oo d , 1958; Azaz an d Shtcycr. 1978). In order to move thi s too th or thodontica llv, the e ntire crown a rea m u s t be dissec ted free of the bone and a pack inserted to p revent the heali ng bone fro m again coming

170

THEORTHODONTIC TREATMENTOF IMPACTED TEETH

- - - - -- - - -- - -- - - - - - - - --

(,)

(b)

Fig u re 7.13 Butto n attachmen ts pon ded buccally a nd lingually to Impacted second molar. (b) A wire !lX1P carrying a J ist,!! lwlix is slott<XI into bu ccal and ling ua l tube s un till' m"I.H band . The wi re loo p is compressed by tying :-lct'l ligatu n'S between the butt on s a nd dista l helix. (c) The fina l result.

(,1)

(el

in to con tact w ith the ena mel surface . A p refor med crown wou ld be n better altern ativ e, bu t access to the tooth is too co mp ro mised to

allow its proper adap tation and cementation. At the same tim e, ortho d ont ic force sh ould be applied 10 the too th and its activity maintai ucd by frequ en t re-Iige tlon .

INFRAOCCLUS ION OF PERMANENT TEETH Ea rlier in thi s cha p ter, we discussed infr aoceluded deciduous tee th. In the permane nt

d entition (Fig. 7.14), the same clinica l p icture is u sua lly referred to as 'pri mary failure of eruption' (Pro ffit and vig. 19H1) Of as 'se condary ret ention' (Raghocbar ct al. 1992), and, in this cond ition, the teeth are sometimes comp letely co vered and no t visible intraora lly. This co nd ition is due to an kylosis (Raghoeba r et .11, 1992). a nd the infrnocclu dcd teeth do not respond to orthod on tic force. It is ge ne rall y believed that the teeth had originally eru p ted and subsequent ly become an kylosed. an d the ir ve rtical developmen t had stopped at that po int. Some o f the more se vere cases may exhibit Intraocclud cd teeth that are situat ed so vertically d istan t fro m the

OTHER SINGLE TEETH

I"

Ib'

Ie)

Fig ure 7.14 (al A normal occlusion of th c posterior teeth is present on thc right sid c. (bl A SC\'L'Te lateral upt'n bite has d eveloped o n till' left sid c, due to primary failure of erupt io n. (e) Thc panoramic radiograph s ho ws n 'lJ' ma rked infr"..cclusion of tIll' left mandibular first molar " nd, to a lesser L'xtL'n t, .11"., n f the [,'fl maxilla ry ",,-'Cun d premolar and firs t molar.

occlusal p lane that it is ha rd to imagine them ever having rea ched the oral cavit y. pa rticularly in the pe rma ne nt d en tition . With continued ver tical g rowth of the ad jace nt teeth a nd alveolar bo ne, the ankyloscd tee th become relatively lowe r a nd lower in the .a lveolus, until they become hidden by the g ing ival tissue and, sometimes , even by bo ne . Giv en tha t these tee th cann ot be orthod onticall y moved , their 'absolu te' a nchorage po tenti al may be exp lo ited to o rt hodontically al ter the position of ne ig hbou ring teeth (Fig. 7.15). Pro ffit a nd Vig (1981) list the cha racteristics of p rimary failu re of e ru p tion as follows: (a) posterior tee th on ly, exclud ing incisors; (b) some erupt and then undergo submer gence as in infrnoc clud cd teeth, others are uneru pted teeth w ith a la rge follicle; (c d eciduous a nd permanent teeth involved; (d ) usually unilatera l a nd asymmetric; (e) tend ency fo r ankylosis, alth ough not ini tia lly an d no res po nSt' to o rthodontic forces; (0 or thodontic treatment leads to ankylos is; (g) no fa mily history. Their conclusion is tha t orthod ontic treat men t for these pa tients is not advised. Contra ry to the vie w o f Proffit a nd Vig (981), howeve r, the re mav be a fam ilial p red ilection (Rag hoebar c t ~l, 1992). Figur e 7.16 shows pa noram ic rad iograp hs of three child ren in one fa mily, toget he r wit h tha t of th e fa ther and the pa te rna l gra nd mothe r, to show the d iffer ing e xp ress ion of the ph cn omenon for each of these af fected F't'r sons. O r thod ont ic e xtru sive forces will hav e no effect on the infrnoccludcd teet h, an d w ill tend to intrud e the adja cen t tee th towar ds the le vel of the infra occluded teet h . By seiz ing the infraocclud ed teet h with extraction forceps and ap ply ing minim al pressure, just sufficien t to obtain a very mino r degree of mob ility of the tee th, one ma y effectively brea k the a nkylot ic ju nction. Howeve r, healing is ra pid, a nd the e nkvlosis w ill soo n become re-csta blish ed . For this reason. orthodontic correction is not u sua lly a tte m pted . Neve rtheless, if a single central incisor tooth is a ffect ed in a yo u ng pa tient, the

172

_ _ _ _ _ __

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ______::..::.....-.--.::..::..c ~~"__________'=__=

~

(b)

Fjgu re 7.15

(a) An in fraoccluded It'll ma xillary

inci~lr. (b)

A peria pi-

cal radiog raph of the tooth to !Ohow absence of lamina d ura over much of the root surface. eel Exp loiting simple levelling a nd align ing a rchwires has also eliminated the deepened ove rbite, by d r,l wi n~ the other tl>cth to the .1nkyluSI..,j tuo th, (Cou rtesy of I'ru fl'Sst ,r Y Zilberrna n.) (el

or thod on tist lll,'y not be p repared to accept the 'no trea tme nt' verdict. 1£ the paren ts und erstand the poor progn os is, treatment may be att empted , provided that attendance for freq ue nt activa tion is assured . Beyond the treatment of these isolated and accessible teet h, attempts to resolved the impac tion of most other tccthwbose roots have undergone ankylosis o r external res or p tion are usually very d isa ppointing . Aside from naturally occu rring ankylosis, there mi' Y be rea son 10 sus pec t the possibility of an ia trogenic va riety . In the past, it was

common to find an oral su rgeon widely expo sin g th e crown of the im pacted tooth, dow n to the ccrn cn to-cnamcl ju nction and bey ond , with consequent ins tru men tation of the root surface of th e tooth . It mi'ly be that some of the blame for the rela tive ly infrequent anky losis of exp osed imp acted teeth is d ue to this type o f unnecessa rily aggressive surgical p roced u re. Extern al root resor p tion that has led to a merging o f the period ontal a nd p upal tiss ues is a rare condition tha t may cause a nonankyloti c infraocclu sion. Treatmen t req u ires

OTHER SINGLE TEETH

(b'

(d

(dl

Fig ure 7.16 A fanuly includ ing (a) grand mother (b ) father and (c-c) thre-e• sib lings sho w ing varyi ng exp ression of p rimary failu re of eru pt ion.

te

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

174

surgical expos ure of the resorp tion defect, its debridement and elimina tion with an ama lgam filling. At the same time , roo t canal therapy mu st be initi aled . After healing, the too th ma y he ali gned u sing convention al or thodon tic methods (Fig. 7.17).

DENTIGEROUS CYST Cysts of any sou rce tha t a rise in close p rox imity to teeth will displace thos e teeth ah ead of the expanding cyst (Sha fer e t .11. 1983). Professional intervention may influence the future o f the d isp laced tooth, depending

upon the type of treatment employed to resolve the cyst. Th e cyst ma y be ope ned. a nd its lin ing completely shelled ou t, in a procedure called e nuclea tio n, with the s urgical flap

replaced 10 com pletel y close off the expos ed bone. The cavity th a t wa s formerly occupied by the Cys t is now scaled off from the ex terior once ag'ain. It will fill w ith blood clot. a nd healing is by prim a ry intention. Th e unerupted too th be comes deeply buried in the newly form ing ho ne, a nd it will need to erupt th ro ugh this repairing tissu e. The p rog nosis for its eruption would a ppear to be in inverse p roportion to its di sta nce from the su rface. Nevertheless. th is a pp roach is pa rticularly su itab le if the cyst is due to chro nic pe riapica l in flam mati o n of the dec id uou s too th, in w hich case it is termed a radicul ar cyst. A de ntigerous cyst a rises from the ou ter en a mel epit heliu m of the develop ing too th, after crow n development has been comp leted , and the cro w n of the tooth is located wi thin the cyst. Th e lin e of tre atment tha t is us ually offe red is referred to as marsupializatio n. Th is inv olves ope ni ng the cys t into the ora l cavity at its most su pe rficial poin t, and maintain ing the pa tency of thi s ori fice over a lon g pe riod of time. Th e cut lin ings of the cyst and the oral mucosa fu se to become con tinuous w ith one a nother. In tim e, tilt' lined cavity becomes smalle r a nd s ma lle r, as bony regeneration occur s, to fill in fro m the bottom up. As it d oc s so, the too th gc nc raly progresses, in the va ngua rd of the reg enera tion . Sponta neous resolution of the impaction

may be expected to occur to a significa nt degree when the cyst is marsupialized , and several truly rema rka ble cases ha ve been reported in the lite ratu re (Fea m e and Lee, 19t18; Sai n c t a t 1992). Treatment by enuclea tion will resu lt in inco mplete removal o f the e pith el ium, a ro und the neck of the too th crown, or accid en tal d islo dgemen t of the too th during the cu rettage p rocess. It would be naive to su ppose that all cases w ill be correct ed so completely, without ve ry con siderable a nd ex tensive additional mecha nothera py. The crown of the too th is full y ex po sed w ithin the cystic cavity. and its surro un ding pe riodontal attach me nt is ve ry ru d im enta ry an d wea k. In la rger cysts, ma rsup ialization will slowly allow the bo ne to regenerat e an d to re pair the lar ge d efect th at the cyst has created . Th e repair occurs slowly, an d the too th will be in the va nguard of thi s progress. Any a ttempt to ,lp pl y orthodontic traction to the too th at this time w ill extrude it ahead of the ad va ncing bone, thereby w eake ni ng its bo ny an d period ont al sup port a nd p rejud icing its longevity. It must be concluded that the cyst must be treated first a nd that it is then importa nt to foll ow up the hea ling p rocess until the ho ne has comple ted the reparati ve fill-in of the bony d efec t. O nly a t tha t point, w h ich w ill be ma ny mon ths la ter , sho uld an assessment be mad e of how mu ch im prove me nt has occu rred nat urally, ho w mu ch more may be expected, a nd how mu ch orthodontic treatment is needed to im pro ve the p ositions of the teeth . It is unl ikely tha t such tr eatmen t will ma ke u p fo r any residual bo ny defect, an d, for thi s reason , pa tience is ad vised, in order to take advantage of the max im um nat ura l poten tial for alveolar bone repair. The re is therefore no value in bonding an a ttachment to the too th a t the time tha t the marsup ialization is u nd ertaken initially . Wh en enucleation, ra the r than marsupializa tion, of the cys t has bee n perfo rmed, the healing process will lea ve the affected tooth where it is - o ften gros sly disp laced fro m its proper pla ce in the arch. Fu r thermore, w ith the lini ng of the cyst re mo ved, th e la rge bony defect w ill fill wit h blood clo t, w ho se undistu rbcd rco rga ntzanon will brin g about hea l-

OTHER SINGLE TEETH

Ia)

Cd l

175

Cd

(bj

' el

(fI

Fig ur e 7.17 (a-cJ Maxillary first premola rs had been e xtrac ted by anot her pr actitioner ', to ,111,,", S1',K1.' for eruption of the u nerupted rightlateral incisor' . Note the relative lack of ve rt ical d evelopmen t and tipping of ,l(1~l ""l1 t tooth , rt'mi I1i.~ ..en t uf an assooatton with lnfruocclu siun. (dl ThO;' pr e-su rgica l peria pical ra di ographic v ie w. (O;') Fo llo w ing or th odon tic s pace R'g" i nin~, s ur~ ical expo"ure reveals the ce rvical resorption defect. Soft resorption-replaceme nt tiss uO;' h"d pre vent ed the uruphon. ({) The re-or phon area was debrided , an d the exposed pulp e xti rp a t,'d an d ro..rt-filled ternporartly w ith calcium hydro xide. Aftc r ,111\,llg.1m restora tion place men t, an eyelet was bo nd c
(Imtjllln, /)

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

176 (Figu re 1.17

co" f irmedl

(h ,

(jl

(i)

(k'

(I)

Ing, by primary intention. To ac hieve this goal. a comple te and herme tic closure o f the surgical fla p w ill be at tempted . to p ro tect the wound fro m in fectio n . The surgeon will p refer not to run the risk of in trod ucing infection, w hich could track alo ng a s tai nless s teel ligatur e wire tha t is liga ted to an atta chment on the im pa cted tooth, when the wound is a relatively large one. It wou ld be preferable to w ait for hea ling to occu r and then to reexpose the too th on a m uch sm aller an d more localized sca le. However, foll owing this sur g tcal p roced ure, s pontaneous im pro veme nt a fter its position h,15 im pro ved may be slig ht , a nd ,1 too th, grossly d isplaced by s uch a cyst, may remain in an u ntenable position, following filling-in of the sur rou nd ing tissues . From the point of vie w of the oral a nd max illofacial surgeon, treatment of this cyst is a priority - often for no reaso n other tha n to

confirm the relatively innoce nt diagnosis. It m ust be re me m be red that, u ntil a biopsy and pathological inves tigation ar e pe rform ed , the d iagnosis is on ly tentative. While the more sinister alt erna tive dia gnoses arc fortunat ely rare, the surgeon cann ot take the chance involved in delay ing th e performan ce of the necessary d iagnostic procedures u ntil the pa tien t is read y to acce p t or thod ontic trea tment. From the orthodontic p oin t of view, the pa tien t sho u ld be prepared for tr ea tmen t, with an un d erstand ing of the demands o f oral hygiene, the need to wear a ppliances a nd the need to expose the im pa cted teeth. These requirements may of ten be fulfil led quite qu ickly, bu t it is u nfair to coerce pa tien ts in to a hu rried decision before they a rc read y, and it is usually counterproductive. It w ould be logical to infer from this discussion that, although the orthodontist h.15 much

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OTHER SINGLE TEETH

to con tribu te to the outcome of the treatment, this contribu tion relates to the latter s tages and not to the immed iate prospects. It wou ld therefore be wise to include the orthod on tist in the decision-making team, bu t inap prop riate for him or her to beco me involved in the ea rly s tages of treatment in any active manne r, u ntil much of the bo ny fillin g-in has occu rred and the too th has migrated down ahead of this.

REFERENCES Azaz B, Sh teye r A (1978) Resorp tion of the crown in im pacted maxill ar y canine. A clinical, rad iographic and histologic stu dy. lilt] Oml Sltrg 7; 167- 71. Becke r, A (1977) The correction o f mesially angula ted semi-impacted mola r tee t h by simp le orthodontic me an s. lsr ] Dent M l.'d 26(2), 17-22.

Becker A, Kamct-R'em RM (1992a) The effects of infraocclu sion: part 1 - tilting of the adjacen t tee th and space loss. Am / Orthod 102: 257-64 . Becker A, Kamei-R'em RM (1992b) The effects of infraocclusion: part 2 - the type of moveme nt of the ad jacent teeth and th eir vertical develo pment. A m / Orthod 102; 302-9. Becker A, Karnei-R'em RM, Steigma n 5 (1992c) The effects of in fraocclusion : part 3 d ental arch leng th and the m id lin e. A lii ! Orthmi 210: 427-33. Becker A, Shochat 5 (1982) Submergence of a d eciduou s tooth, its ramifications on th e d entition and treat ment of the res ulting malocclu sion. Am ! Ort/lOd 81; 240-4. Blackwood HlJ (1958) Resorp tion of enamel and d en tine in the unerupted tooth. Oral SlIrg Oral Ml'd Oral Patl, 11: 79--85. Breznia k N , bcn-Yehuda A, Sha plra Y (1993) Un usua l mand ibu lar canine trans position: a case report. Am / Orthod De1Itofae Orthop 104: 91-4. Fca rnc 1. Lee RT (1988) Fav ourable spontaneous eru ption of severely d isp laced maxil-

lary canines with associated follicu lar d isturba nce. Br / Orthoa 15: 93-8. Kohavi D, Zilbe rman Y, Becker A (1984) Period on ta l status following the alignment o f buccall y ecto pic maxillary canine teeth. Am / Ortl/Od 85: 78-82. Ku rol J (1984) Infraocelusion o f primary molars. An epidemiological, famili al, long itud inal, clin ical and his tological stud y. Steed Dent J 21 (SII/'l1l): 1-67. Kur ol I, Th iland er B (1984) Infraocelu sion of primary ma IMS and the effect on occlus al d evelopmen t, a long itu d ina l s tu dy . Eur / Orthod 6: 277- 93. Majourau A, Norton LA (1995) Upr igh ting impacted seco nd mola rs with segmen ted sp ri ngs. Am / Or/hod Dm tofa e Or/hop 107: 235-8. Pro ffit WR (1992) Contemporary Ortlwdolltics. Mosby Year Book , S1. Lou is. Proffit WR, Vig KWL (1981) Primary fail ure of eru ptio n: ,1 possible cause of posteri or open bite. Am / Ort1lt~t 80: 173-90.

Raghocbar, Jansen HW, Iongcblocd WL, Boering G. Vissink A (1992) Secondary reten tion of perman ent mo lars: an assessment of ankylosis by scanning elec tron and light microscopy . 8r / Oral Maxillafae SlIrX30: 50-5. Richa rd son ME, Richa rdso n A 0 9(3) Lo wer third molar d evelopm ent subsequent to second mola r extraction . Am J Orthod Dl·"tofae OrtllOp 104: 566-74. Sain DR, Hollis WA, Togrye A I~ (1992) Correction of su periorly d ispla ced impacted canine du e to a large d en tigero us cys t. Am ] Grmod Delltofne OrtllOp 102; 270- 6. Sha fer WG, Hine MK, Levy BM (lY H3) A Tl.'xtlltltJk of Oml PatlJo!oxy, 4th ed n . WB Sau nders, Philad elphia. Stag ge rs JA 09Y 0) A comp aris on of result s of second molar and first prem olar extraction trea tmen t. Am / Ortnod Dt'1Itafae Ortllo,' 98; 430-6.

Wilso n HE (1966) The extraction o f second .permane nt mola rs as a th erapeutic mea su re. Trans Enr Ort//Od Soc 42; 141- 5.

8 IMPACTED TEETH IN TH E ADULT PATIENT

CONTENTS • Neglect and di sg ui se • Management • The need for temporary pr o sthe ses during tre atm ent • Supp lementary clin ical c oncerns • Temporary prosthetic rep lacement and tooth tr anspo sition • The un erupted th ird mol ar as a potential br idg e abutment • Implant anchorage

NEGLECT AND DISGUISE A sma ll bu l significan t numbe r of u ntreated impacted teeth will eventu ally find some way of erupting in to the mou th - ,..-ithou t trea tment - although this may be ma ny yea rs after thei r normal eruption time , and then o ften into a n ectopic eru ption site. Th is is par ticu larly true of maxillary canines (Thtl and er and Jacobson, 1968), an d in d irect contrad iction of the po pular view that eruption po tential is los t w hen the root apex d oses (Kokich and Ma thews, 1993). Nevertheless, a good proportion will remain unerupted and as ym ptomatic for many yea rs. Pros thetis ts ar e all aware of the occasional p atient com plain ing of the eru ption of a tooth und er a den tu re, often many years after the pa tie nt had becom e o the rw ise ed entul ous. For the most par t, d uri ng the childhoo d of the pa rtic ula r adult pa tient concerned , ad vice was proba bly sough t and rejected , with the reasons fo r this being very varied . The patien t may have been an orth od ontically u nm anageable child at the appropri ate age; perhaps the dentist or orthod on tist was ins uf ficientlv convinci ng in the task of infonning th e pa ren t of the consequences o f non-treatment ; or the

parents' leve l o f denta l a war en ess was inad equ ate, the id ea tha t surgery wou ld be needed was possibly ab horrent to the paren ts, or simply the cos t and d ur ation of the proposed trea tment were unacceptable. Ju st occasionally, a surgical ex posure p rocedu re will ha ve bee n carried out a t the app rop riate time , have failed to elicit eruption an d was not the n followed up. Some impacted teeth, particu la rly maxillary canines , may sim p ly never have been d iagnosed . O ne fu rther poss ibility tha t is not u nfamilia r is that a dentis t succumbed to the plead ings of the parent to 'd o so mething tem porar y to make-it-look-good'. u ntil they wo u ld be ready for th e de finiti ve treatment - a tim e that never arrived! It may be diffic ult for the orthod ontist to imagine the sit ua tion wh ere a pa tient has reached ad u lthood with a central incisor still impa cted . Th is will have bee n obvio us fro m around the age of 7 yea rs, bu t the pa tient on ly sought treatment in his / he r twenties o r, possibly, ev enla ter. This type of neglect is indeed unusu al, and its p revalen ce seems likely to vary from cou ntry to country, in inverse p roportion to the leve l of dental awareness in the po pu lation. A cou ntry that offers its citizens some fonn of national d en tal insu rance may

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

180

- - - - - -- - - - - - - - - - - - -- - -

(.,

(b,

Figure 8.1

Impacted right m.lKilla ry central inciso r (al repla ced by poorly matched arti ficial tooth on 'flippe r' (spoon) dentur e (b).

Fig ure 8.2 Im pacted right ma xillary central incisor . The rig ht lateral incisor cro wn has been enlarged by a com posite buildup.

be expected to have a lower prevalence among its adults, sin ce one woul d hope that treatment would hav e been car ried ou t at the appropria te time, given the relative freedom from financial constrai nts in a welfare state. Cost, however, is not the only fact or and probably not ev en the d ominant one. Whatever the reason, however, the adult pa tient will usually pr esent with the incisor an omaly un su ccessfu lly d isgui sed in one of three way s.

2

3 1

A retained d eciduous tooth may hav e bee n enlarged with the ad d ition of composite mate rial, althou gh this w ill prob-

ably have improved only its len g th. Any increase in its width will be lim ited by th e red uced mesio-d ista l space availab le to the tooth, the res ult of the marked mesi al tip ping of th e adj acen t lateral incisor and the cen tra l incisor of the opposite side. This reduced space may hav e been main tained wi th a 'flip per' (spoo n ) partial denture, carrying a sin gle and po orly matched small tooth (Fig. 8.O. The latera l incisor ma y have been enlarged, with the u se of compos ite material in an attem pt to simulate the shape of the impact ed cen tra l inciso r
'"

IMPACTED TEETH IN THE ADU LT PATIENT

There arc serio us d rawbacks with each of these treatm ent alterna tives, which focu s p rincipally o n the ve ry poor appeara nce o f the resu lts. The abse nce or red uction in size o f a cen tral inciso r is always ob vious, as too is an y significant shift in a max illa ry dental mid line, ev en to the casua l observ er. The tipp ing of the two teet h adjacent to the im pacted incisor is too severe to esca pe notice, an d the angle o f the latera l incisor is too acu te for its long ax is to be visu ally ' realig ned ' by co mposite additio ns or by reshaping. The narrowness o f the neck of the too th makes an aes the tically co nvincing reco nstruction as a cen tral incisor im possible.

MANAGEMENT It is quite clea r tha t, under these circums tances, the first an d mos t important prerequ isite to any form of trea tme n t for the missing too th is to p rovide the maxilla ry dent al ar ch with an id eal shape in each of the three planes of space. In practical terms, this means the followin g. 1

2

3

lr1.'t'//iIlK and alignillg li't' entire dell tal orcti .

All ectopi cally p laced teeth will need to be brought in to an ideal ar ch form, teeth will need to be aligned in a single, un iform occlus al pla ne an d all rot ations d ealt with. Reopen ing a space of euitabtc II/csio-dista/ width iu order to occowoda te the impacted tootlt ill t!le arch. Co rrecting the pala tal inclin ati on of the canine and tipping the latera l inciso r of the same sid e an d the cen tra l an d lateral incisor of the opposite side will usually provid e adequate space, although d ista l movem en t, extraction or int erp roximal enamel st ripp ing may need to be considered. Correcting lI,e dt'lltal midline to be continuOIlS with tilt' touxr 111/11 with fil e midline of the face. Th is is normally ach ieved as a res ult of the reopening of space, but it m ay req uire the usc o f coil sp rings or an terior, obliqu e, in termax illary clas tics as pa rt of

a. more com prehen sive orthod ontic applian ce p rogram me. 4

Closing dowll all anterior O/'t'll bitt' and brillgillS tilt' tedll into oc clusion, This is p roba bly bes t achie ved by properly aligning the molar tubes a nd by altering br acket height on the anterior tee th, th ereby b ringing abo ut the desir ed extru sion of the tee th. However, a nteri or ve rtical elas tics are of ma terial help in this situ ation .

Once these ai ms ha ve been achieved , the patien t is read y for that stage in treatment when all reso urces w ill need to be concentrat ed on the im pacted too th . The en tire dental arch must be consolidated into a compound and united anc horage u nit, to which the unerup ted too th will be d rawn . In Chapters 6 and 7, we mentioned that teeth tha t ha ve been impa cted for many years someti mes undergo pa thological cha nge that prevents their eru p tion (AZ.1Z and Shtcy cr. 1978), even whe n all other factors are favo urable. It is by no me ans al ways possible to d iagnose pa thol ogical change from a rad iograph, u nless there is a loss o f the follicu lar sac and actual ename l resorpt ion has become ev ident over wide areas of the su rface of the un erupted tooth. It is the refo re true to say that, whenever an adult pa tien t presen ts for the trea tme nt of an im pac ted tooth, a calcu late d risk is taken in offering th is kind of treatment to resolve the impaction. In the most ad ve rse of circum stan ces, the central incisor too th w ill have to be extracted an d perhaps su rgically reimpla nted . In tha t event. the preparation of the d ent al ar ch d escribed abov e will hav e pro vid ed optimal clinical condition s to accept the implant or other form of artificial res tora tion of the space. An ideal po ntic width is pres ent, all other teeth arc alig ned and the occlusi on is goo d . However, the su rgical remova l of a grossly displaced im pacted too th, high above its no rmal position , will leav e a. cons iderable and unsightly bony defect. This will be d ifficu lt to conceal in the g ing ival area around a fixed p ros thesis, a nd will not lend itself to the placin g of an Impla nt withou t suit ab le an d pri or oss eo us rid ge rec onstruction

182

________ _ ____=-=----=

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THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(Sailer, 1989; Richardson and Cawood, 1991; Sim ion ct al, I1J92; Lus tma nn and Lcwins tein, 1995). The pa tie nt m ust be brought into the d ecision-ma klng p rocess from the outset and s ho uld be infor med of the po ten tial ad van -

tages of each of the stages of the treatment. Prognosis for the s uccess of the pre-s ur gical st ages of the trea tme nt is excellen t, but it is not so certain for the alignme nt of the im pacted too th . O ffe ring the treatment pla n to the pa tient is therefo re p robably bes t acco m plish ed if it is based on explaining the benefits of the limited objectives. i.e. ali gning the teeth for the pu rposes of achieving Improved cond itions for the co nstruction of a convent ional prosthod ontic o r im p la nt-bo rn e replace ment. The added bo nus that will be d eri ved from success in the resolution of the im paction may then be properly brough t in to pe rs pec tive to provid e the d es irable add ed incentive. By w ha tever mean s the value of the tr ea tmen t is ex plai ned. ca re sho u ld be taken to fu lly inform the pa tient tha t the possibility of failu re to bring the im pacted tooth into the arch is rea l. bu t that contingency p la ns a rc a vailable in thi s d is ap poin ting eventu ality.

THE NEED FOR TEMPORARY PROSTHESES DURING TREATMENT For the ad ult patient , planne d orthodontic space -open in g for an uneru p ted a nter ior tooth is a dau nting prospect. A ll central a nd la teral incisors a nd ma ny ma xilla ry can ines requ ire some form of im med ia te temporary prosthetic replacement until such time as the perma nen t tooth comes in to its place. With so me pa tient s. particularly those more concerned wit h th eir appl'aran ce, or tho se who ha ve a broader s mile or a wider dental disp la y that is evident in facial expression an d social inter cou rse, there may be a need to artificia lly rep lace even p remolar teeth . If the a rtificial res tora tion ta kes the form of a re movable pla te carryi ng a sing le tooth, a 'flip pe r' (spoon) dentur e, the pa tie nt ma y ha ve consid e rab le d ifficu lty becoming accu s-

tomcd to it, eve n if its retention is ini tia lly adequa te. O f great er con cern , ho cvever , is th e fact tha t the ad jace nt teet h a nd ma ny othe rs need to be moved d ur in g the or thod ontic trea tme nt, w hic h w ill ra pid ly make t his a rtificial dentu re ill-fittin g. Fu rthe rmore, its adapta tion to the con to ur of the othe r teeth in the jaw may actually inte rfe re w ith the p la nne d or thodontic move me nt. For thi s type of a rt ificial replacement to be successful, Ad ams' clas ps ma y ha ve to be used o n the second mo lars, or, altern a tively, a modified circumferential clas p ma y hoo k over the bu ccal tubes of the first mo la rs. These tee th are often excl ud ed from the pla nn ed dental movements, and ma y so metim es be helpful in reta ining such a pla te, alt ho ugh the d ista nce between the clasps an d an incisor pon tic may be th e cause of an unaccep table degree of ins tability. Clearly, more sa tisfactory alterna tiv e met hods of artificial re placement a re essential to the successful pursuit of treatm en t for the adult pa tient, an d these mu s t provide a n a nsw er to the several sho rtco mings of the 'flipper' de ntu re . Indeed , given a little thought in their d es ign a nd ra the r tha n their pla yi ng the role of the villain of the piece, assistan ce ma y be d er ived from the met hod of artificial replacem e nt, w hich ma y contribu te to the ope ra tion of the active orthod ontic app lia nce.

The active removab le plate If a rem ov ab le p la te is to be w orn to hold th e artificial too th in pla ce, it makes good se nse to au gment tha t pla te w ith active elements that w ill als o produce tooth movement. Looked at in a d iffe re nt way, this mea ns the designing of a sim p le removable or tho dontic ap pliance, ca rrying sp rings of one sort or another tha t a rc ai med a t realign ing the teeth to reopen the ant er ior space an d , at the same time, to fill that space w ith an art ificial too th. This me thod has so me im porta n t ad va ntag es . The act ive p la te is s tra tgh forw ard an d easy to use, requ iring very limited ex pe rtise

IMPACTED TEETH IN THE ADULT PATIENT

in its adj ustment o f the forces applied and in their d irection. The artificial tooth may be easily altered in size as space-opening occurs, to main tain appea rance. However, the active removable appliance is un ab le o f producing more than tipp ing movemen ts of the ad jacent tee th. Methods ha ve been described where a removable app liance has been used to p roduce the extrusive movements needed to reso lve the impaction of teeth
The solde red palatal arch In the ad ult patient, the sco pe of or thod ontic correction that is planned tends to be more localized and less comp rehensive, particula rly when a single and gro ssly di sp laced tooth is present. Accordingly, the first maxillary molar teeth are most com monly used as anc ho r teeth for the fixed appliance, and their orthodon tic m ovem ent is not usually requ ired . Th is being so, the buccal as pect s of these teeth and bu ccal/ labial aspects of the teeth mo re anteriorly placed will be used to carry the orthodo ntic brackets, archwires and au xiliary. This leaves the pa latal side of the teeth and the palate area free and available to serve the int erests of the patient' s ap pea ra nce.

The missing central incisor A soldered pa latal arch, based on the molar bands, can provi de a n orthod ontic a ppliance with a n excellen t anchorage base, a t the same

time as actin g as the vehicle for a sa tisfactory p rosthetic replacemen t. Several approaches are avail able, and they depend on the ada p tation o f well-fitting p re formed ort hod ontic bands to the molar tee th a nd their accurate transference to a plas ter working model of the jaw. On the working mod el, a palatal arch is fabricated and soldered on the pal atal side of the molar band s. A small wire extension may then be soldered or bent into the anterior por tion of the palatal arch, extendi ng towards the space in the arch and terminating immed iately palatal to the position of the missing too th, with a configuration that will mechanically retain an ar tificial acry lic tooth. The exact location of the artificial tooth should be deci ded in accordance with the projected treatment goal s of the case and not ncccsse rBy in line with the adja cent nat ural teeth. Thus, if an overjet is to be closed or a crossbit e treated, th e siting of the artificial tooth should be mad e according to the intend ed final, post-treatment, position of the adjacent tee th. An occluded plaster cas t of the opposite jaw is therefore necessary to assist in its accurate p lacemen t. This is the Simples t app roa ch of th is type and it offers the pa tient a good artificial replacement, which is well tolera ted (Figs 8.3a,b). It also allo ws the ad jacent tee th to be aligned withou t hind rance, while act ually enh ancing the anchorage value of the molars du ring ret raction of a pro cumbent labial seg m erit. The anchor molars cannot be rotated or tip ped easily wh en using ho rizontal , in tramaxillary, elastics, ow ing to the stabilizing effect of the rigid soldered pa latal arch. A sig nificant and valuable refi nement of this appro ach involves bonding o conventional bracket to the artificial tooth, as with the o ther teeth . This makes the artificial tooth aesthetica lly compro mised to a sim ilar d egree as th e other teeth an d th erefore less recogn tzable as other than a part of the natura l d en tition. Since this too th is rigid ly a ttached to the molar teeth and at a fixed d istance fro m them, this method has m uch mo re to offer . Its integrati on in to the appliance sys tem ma kes alignm ent and levelling mo re accurate and more rapid . Ad diti ona lly, the need for elas tic 4

THE ORTHODONTIC TREA TMENT OF IMPACT ED TEETH

184

----------------------

(.J

Figure 8.3

(a) Same patil'nl as in Fig. 8.2. to show initial stages of al igomeot and ..pan- opening. The com posite buildup of the maxillary rightlatera l incisor is still in place. (b) Space has been reopened. the composite build-u p of the lateral incisor has been removed, and the artificial cent ra l incisor is in place, at tach ed to the soldered pala ta l arc h. (bJ

traction to reduce the ove rjet will be eliminated, since the use of the init ial fine- gauge and ideal archforms in the early weeks of treatment will perform this without any fur-

ther modi fication . The distance and relationship bet ween mola rs and the artificial incisor is fixed to the Ideal length and position by the palatal arch . Thu s a progression of id eal wire arch for ms will align all other teet h with in that a rch. Essen tially, by lin king the ar chw ire to the fixed pontic, in its no rma l ove rjet and ov erbite location, the firs t stage of mechan-

otherapy. which generally deals with initial levelling an d alig nment onl y, now comes to

includ e aut om at ic overjet an d ov erbite reduction . The ov erall length of the heavy palat al arch p rovides it with a de gr ee of ela sticity, d esp ite its heav y gauge. Thus, wh ile carrying a temporary prosthet ic replacement, it may be us ed to widen or co ns trict the den tal arch . In the present con text, however, it has one other possib le function, wh ich is less obviou s, bu t most helpful. The palatal arch has the potential to p rovide the vertical componen t o f force that is needed to close a n anterior open bite and subseq uently the ve rtical tr action needed to resolve the incisor impaction (Fig. 8.4).

IMPACTED TEETH IN THE ADULT PATIENT

Fig u re 8.4

Cd

Cd '

Closi ng the an teri or open b ite, in the sa me pa tient as in Fig. 8.2. (al The so ld ered arch has been d eflected s lightly verticall y d ownward s to elongate the a rtificial tooth. (b J Placement o f th e archwire shows the d eg ree of vertical displacement. The artificial toot h is now full y engaged in the archwire. (e) The e xtrusive force of the pala ta l archwire clUM'S o ff th e o pe n bile. (d ) Th e peria pica l vie w sho ws the im pact ed too th to be dil aa:rated. The palatal arch Is clear ly seen, wit h the Iorward-poinung loop used to carry the radiolucen t arti ficia l tooth. An o rthodon tic b rack et is also attached to th is rad io log icall y invisible too th , (e ) pre-treatment tangenitia l radiograph. (0 Bondin g of an eye tetto the a na to m ica lly pala ta l aspect o f the incisor cro w n, (g) Th e elas tic chain is gen tly raised a nd ensnared in the pigta il to provide immediate and co ntroll ed vertica l traction . (h) Pos t-surgica l peri a p ical view to show the bonded ey elet and p ig ta ils ligat u re , (i) The tangenti al view pos t-surge ry. ,.,h owing the leng th of the unseen part of the ligature an d the relative heights of th e tooth, the ligature ext remity and the occlu sa l plane. (j) The im pact ed tooth has e ru pted 5 mo n ths lntcr : note the red u ction uf the cervical po rtion vI the artificialtooth to all ow fo r furthe r progres s. Tra ctio n was mode to a newly placed labia l a ttach ment a t th is ju ncture. (k ) Pe riapica l vie w o f the dila ccratc incisor a t the completi o n o f treatment. (J) Th e orth odon tic res u lt : no te th e gingi val appearan ce of the tre ated and untrea ted ma xillary cen tra l inciso rs . (Figu re 8.4 am lillllrd l

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

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IMPACTED TEETH IN THE ADULT PATIENT

187

(Figu re 8.4 COl lf i ,med )

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The missing maxillary canine Aside from third molars and in com mon with the youn ger pa tient. the too th most frequ ently fou nd to be imp acted in the ad ult is the maxill ary cani ne. The principles of d iagnosis, treatment planni ng and appliance th erapy in the adult arc no different from those o f the ch ild, although certain demands are made by the adul t pa tien t, wh ich may make trea tment met hod s less rou tine and more individualized . However, the du ration of such trea tmen t in the ovcr-zy-ycar-old age grou p is likely to be sign ificantl y longer than for the child pa tien t (Herzer et al, 19(4). In a case wit h Impac ted incisor teet h, the

presence of a palatal arch does not encroach on th e area where surgical exposure and postsurgical swe lling arc likely to occur, pro vided that th e anterior po rtion of the palatal arch is not brought too far forwa rd . A 'cut-back' des ign is usually mos t appropriate. In order to expose a palatally dis p laced maxillary can ine, a wide area of pala tal mucosa may need to be reflected back, and this, toge ther wi th the possib le sequel of even a m inimal degree of po st-su rgical oedema, effectively d isqualifies the usc of a rigid pala tal arch in these circumsta nces. A trans-palatal bar, such as a Coshgar ian or a simple 'across-the-p alate' soldered arc h, are usually sufficien tly di stan t from the su rgical

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ...::..:=-=-...::..:::.::..:' -----=----=:::.::..:...::..:=--'-----'--'' '---

188

site to be used in these circu ms tances. They ca nno t be used for prosthetic replacement , and their only function is to enha nce the an chorage. However, in combina tion with a buccal arm, they may be very useful and hav e definite indications. In the cast' illustra ted in Fig. 8.5, the adapted mola r band s are transferred to a p laster wo rking model an d a transpalatal arc h is soldered to the palatal side of the bands . Molar tubes are welded to the buccal side of the ba nds, and , gingival to these tubes , a heavy bucca l arm is so lde red, ex tending vertically upwards into the sulcus. The arm is then fabricated to follow the depth of the sul cus anteriorly until it reaches the canine area, where it aga in dips inferiorly, to term inate in a loo p in the canine site. An artificial acry lic tooth is cured. into this retention loop, in th e place of the missing permanent canine. Immediately after extraction of the natural dec iduous tooth. the unit. which comprises two molar bands, a palatal arch an d a buccal arm, is cemented into p lace, followed by appropriate o rthodontic attachments on the ot her teeth. After initial alig nment and space opening, the imp acted canine is exposed su rgically, from the buccal or palatal side, as approp riate to the case. Traction may then be applied in the normal way, bu t carried ou t beh ind the facade of the buccally retained artificial toot h. As with the placem ent of a bracket on the artificial cent ra l incisor, d escribed above, it is ad vantageous to design the integ ration of these prost hetic exped ients into the orthodontic appliance sys tem in su ch a way th at the y may contribu te materially to the efficiency of the ap pliance. Thu s, a fter cemen tation of the bands carrying these ad d itions, the buccal arm is d isp laced fu rther buccally, so th at its passive po sition is a few millimetres bu ccal to its original location . If it is now tied d irectly to th e impacted canine, using a steel liga ture, th is w ill rea lign the di sp laced buccal arm an d artificial too th. Th e ene rgy sto red by this long a nd elastic bu ccal arm will now pro vide the trac tion needed to draw the impact ed too th towards its p lace in the arch.

SUPPLEMENTARY CLINICAL CONCERNS The basic p remise for the use of these palatal and buccal ar ches has been that the first molar tooth d oes not requ ire to be or thodontically moved . Ne edless to say, there are cases in wh ich movement o f the firs t molars is an essentia l pa rt o f the orthodontic stra tegy of the treatment of a particular adult. These ma y include cases where the re is a pronou nced rotation or a palatal or buccal d isplacement of this tooth, bu t they may also include the p remolar extraction cases where closure of excess space fro m the distal will be needed . In these cases, several options are still available to allow the smooth pursuit of orthodontic treatment In the first place , a single buccally or palatally displaced molar tooth, w hich it is p lanned to u se as an anchor u nit, may be tip ped into its place using a removable applia nce . This appliance will need to carry some form o f buccal or palata l spring, which will be used to mov e the too th in th e appropriate direction, su ita ble clas ps to retain the applia nce firm ly in posi tion, an d , possibly, an artificial tooth to replace the impacted incisor tooth in the interim. Alternatively, an existing 'flippe r' denture may be aug men ted to inco rpo rate the same clasp an d s pr ing elements. When more extensive moveme nt of the anchor tee th is req uired, th is is us ually enacted in a prepara tory orthodonti c trea tmen t pha se, w hich is aime d at producing good alignmen t by uprighting, ro tating and torq u ein g th e teeth, whil e lim iting the applian ce work and movem en t of the anterior teeth to levelling and aligni ng. Du rin g this proced ure, it is importan t to en able the patien t who has bee n wea rin g an artificial denture to continue to do so un til s uch time as the alignmen t stage is complete. Similar ly, an over-re tained de ciduous inciso r too th shou ld be allowed to remain un til the planned tempora ry pros thetic rehabilitation becomes p ractical. With the sa tisfactory completio n of the prep ara tory orthod ontic treatment phase and the tee th having been brou ght into good alignment. the precise

IMPACTED TEETH IN THE ADULT PATIENT

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(b )

(d

(d)

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Figure 8.5 (a-e) A 47-yt'ar-old female has a maxillary left canine tha t is impa cted adjolCt'nt 10 ,1 pvg-Sh,l f....-d latcru l inciso r. The eru pted rig ht ca nine is in the place of the congen ilillly abst'nt lat",rill in6",,'r. (d) The p,lt il'nt Wl'.1I'" ,1 removable pa rtial plate to fill the canine sill'S on each side, (e-g) The molar bands arc in\l'rc on nl'C!I'l.I by ,1 soldered 'ac ross-the-pala tal' heavy arch (nol Sl.'l'n). A high buccal ar m is sold ered on each molar ba nd, car rymg an artificial canine too th, to replace the disc arded pout i"l plat e. (h) A small hook is cured into the left artificial can ine, and the buccal ar m is deflec ted buccally and inferiorly at the time of su rgicalexposure of the impacted canine. (i) Ligating the impacted tooth 10 the ar tificialtou th a p plil~ extrusive and buccalt raction. (j-I) The left cilnine has been brought into its place, an d a fixed pa rtial (l'igure 8.5 CQll ti ll Ul'd 1 prost hesis fills the golp on the ri~ht side.

190

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(Figure 11.5 cpu/;m/l·,/j

( i)

lp

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191

IMPACTED TEETH IN THE ADULTPATIENT

reope ning o f the space for the missing too th is under tak en . At this poin t, the palatal arch is const ru cted on a plas ter mod el, into which the molar ba nds have been accu rately seated and th e art ificial too th s ited, as d escribed above. The patient' s dent ur e is no w d isca rd ed or the over-retained d eciduous too th is extracted, an d the palatal arc h ca rrying the arti ficial incisor too th is inserted by rece rnenti ng the molar bands to their form er place. When moving tee th mesic-distally along an archwi re with a multibrncketcd fixed appliance, the establishment of interproximal contac ts between the teeth ena bles a hig h d egree of co ntrol of ind ivid ual tooth position . Once this has been achieved, uprighting and torqucing movements may be carried out , wi th care being taken to see th at the spaces d o not reo pen. The d esired treatment result includes dosed contacts. In the situation whe re a tooth is uneru p ted and space must be made for it , the orthod on tis t should err on the side of reo pen ing excess space an d then ma intaining it until the too th reaches its p lace. However , to d o so, the spa ce needs to be maintained du ring the ma ny fu rthe r months of treatment, when the adjacent teeth will be alterin g their relationships to one ano ther. Wh ile atte ntio n is d iverted to the details o f the treatme nt in these other areas, chang es may inadverte ntly alter the space. The orig inal co il spring , whic h may have ope ned the space, must be de-activated , since it will otherwise con tinue to inc rea se the d imensions of the space. However, th e p lacement of acti ve root-upright ing springs will tend to close th e spncc by compress ing the spr ing . The size of the artificial incisor tooth and its mesio-d ist al siting mny be very usefu l in hold ing the ach iev ed space and in ideall y placing the adja cen t teeth, reg ard less of their locations and wit ho u t the need for the coil spr ing or the ligation o f grou ps of teeth . The natural teeth nrc s wif tly broug ht into interproxim al co ntacts with the artificial too th and wit h each other, and this status is the n simple to mai ntain.

TEMPORARY PROSTHETIC REPLACEMENT AND TOOTH TRANSPOSITION Rarely, on e or more of the im pacted tee th is also trans posed. For the most pa r t. it is preferable to align the teeth in thei r transposed. positions, rather than to try to retranspose them to the ir ideal po sitions, for reaso ns already d iscussed in Chap ter 6. Nevertheless, there are situations in whic h th is may be the p referred line o f treatment. Given the hig h fn..' quency of m issing lateral incisors in cases of trans posi tion of maxillary canine/ first premolar transpos ition (Peck et at 1993), treatment of the tr ansposition may have to consider the artificial replacemen t of the missing teeth during the ap pliance therapy. The use of a pa latal arch to augment th e anchorage value of the mo lar teeth an d to provide the vehicle for the artificial replaceme nt teet h is an effecti ve way to d eal with this problem (Fig. 8.6). By tying in a lab ial archwire from mol ar to molar, p assi ng through a bracket on each of the ar tificial lateral incisors, these strategic points on the perim eter of the arch are defined in relation to one ano the r, since the incisor po n tics are also rigid ly fixed to the molar ba nds on the lingual side. The sma ll sectio n o f lab ial arc h wi re tha t intervenes betw een mo la r tube an d incisor bracke t is therefore we ll supported in ter ms of anchorag e, an d may be used to slide the mo re bu ccal of the tr an sp osed teet h (usuall y the canine) in the mesio-di stal p lan e. At th e same time , the more lingua l of th e transp osed teeth must be moved fu rther lingually to allow its partner to pass by. Finally. it mu st be moved in the opposite m esio-d is tal d irection and back in the line of the arch . To achieve this, the mo re lingual tooth may be liga ted to several di fferen t and strateg icall y plan ned loops and cross-p ieces, which will hav e been p rep ared on the pal atal arc h ahead of time, using clastic threa d . Once again, positive usc is mad e of the palatal arch as an int eg ral part of the ortho donti c appl tan ce svs tem, and it is nut merel y a means of su pporting an ar tificial too th. .

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ~:..::.~==__=____=_~=__=__~__=_=_='__

192

(a

(bl

(d

'dl

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Figu re 8.6 (a-c) A 27.yt"lT-1l1d (('m,llt' with congenitally absent max illary lat eral ind sllN and maxilla ry canine/first premol ar bilat-

eral tran spos ition . The d ecid uous cani nes and right late ra l incisor art' still presen t. (dl Occlusal view of rnoxillary ;:m:h. Intra -ora l views after extraction of decid uou s teet h. (h-jl Treatment progress. !>O.'CII from th.. right side. (k,D U~ uf palatal
(e- h )

IMPACTED TEETH IN THE ADULT PATIENT (Fig ure 8.6

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THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

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THE UNERUPTED THIRD MOLAR AS A POTENTIAL BRIDGE ABUTMENT OR AS AN ANTAGONIST FOR AN UNOPPOSED TOOTH

in providi ng the vertical traction that is ai med at enhancing the eruptive po ten tial of an u neru pted third mola r. Elastic traction of the too th to the opposing jaw is a useful meth od , an d has bee n referred to above (O rton et al. 1995), bu t the use of removable appliances in the ad ult patient is unreliabl e. Adu lts have far greater di fficulty becoming accu stomed to the bulk of the remo vable pla te and its interference wit h ma sticatory and articu lar function . The use of a fixed ma ndibula r a ppliance offers a mu ch more 5..1ttsfac tory and d im ensionally mod est alternative, w hich interferes ne ither with eating nor with speec h . Fur thermore, if the mandibu lar ap pliance is to be used onlv as a source of anc horage, brackets and arch\ vircs may be d ispe nsed with, making it very inconspicuous indeed . A n unopposed seco nd mo lar in the opposite arch is the tooth that faces the poten tial

In th e previous chapter, we d iscussed the uprighttng of molar teeth tha t were preven ted from er u p ting, partially or fu lly, by th eir relation ship with an imm edi ate mes ial neigh bour. It is pertinen t in the con text of the presen t chap ter to d iscu ss a di fferent scenario

tha t commonly presents. Followi ng the extraction of poste rior tee th in the ad u lt p atient , the estab lishment of a 'free- end edentulous saddle' makes or al rehabilitation problemat ic. Th is ma y sometimes find a potentia lly convenient so lu tion in the di scovery of an uneru pted third molar. However, the absence of standing posterior teeth creates mechanotherapeutic d ifficul ties

,I

IMPACTED TEETH IN THE ADULT PATIENT

•

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Figu re 8.1 (a) A 54-ye,u-old male pa tient, showing unopposed ma nd ibular right second mo la r. (b) C lose-up views of buccally displaced an d pa rtially erupted third mola r. (e) A 0.024" round wi re has been ada pted to buccal surfaces of the pre molar and mola r teeth on the man di bular mod el. Note the reten tion loops an d welded mesh pads. The d istal extremity is in the s hape of a hoo k, w hich has been covered w ith solder for patien t com fort. ld ) The Lsbaped elastic co nfigu ra tion for ease of place men t an d wide ran ge of act ion . (e) Following eruption , a pa rtially bonded a ppliance is used to upright the thi rd mo lar . Additional anchorage is derived from a soldered palatal arch from first molar to first mola r. (0 The final stage of treatmen t.

196

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

- - - - - - - -- - -- - - - - - - - - - -

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(b'

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(d Figu re 8.8

Ia.b) An osseo-inl...grak.J impl,]nl h,l S b een placed in the ma\iJIary left second prem olar site. A partially l'ru pil'd and di ..ta lly lip ped th ird molar shows o nly ils mesi al surface and mesia l occlusal cu sps. « l An elast o me ric c hain module apphcs fo rce 10 the implan t post, \';.1 the bo nd ed eyelet o n the mola r. (d) Vertical force is a pplied tu ,1 mandibula r bo nded bucca l ba r, to achieve occlusal con tact. (e) Fully occludi ng third mola r . Noll' the use of three bu tto n a ttac hm e nts to p n wi d e vertical force wi th buccal o r lingual vect ors. as needed. The mesial bu tto n is to prevent the ela..tic fro m im pinging on the- gingiva. If, g) Pre- an d pos t-trea tment rad iogra phs . (h) Late ra l vicw of IIw prost hodon\ic reconstruclion . (Fig ure 8.8 amtil/IIN )

197

IMPACTEDTEETH IN THE ADULT PATIENT

(Figu re 8.8

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erup tion site and pro posed final position o f the un erupted tooth, while pr emo lars may be occlud ing further for ward . Vertical extru sion o f tee th requi res relatively low fo rce va lues; neve rtheless, it is importan t to include several 1I..-cth in the a nchor u nit and to rigid ly link them together, to preve nt or limit the ir reactive extr us ion. Using a plas ter model of th e patient' s opposing jaw, a len gt h of 0.024" <0.6 mm) s tainless sIL-e1 w ire is adapted to the gen eral fonn of the buccal surfaces of the teeth, from second molar to the first or second prem olar (Fig. 8.7). The wire extend s very slig h tly mesiall y to the first prem olar and a few millimeters d istally to the second mo lar, wh ere it is bent into a hook. Those parts of the wire immed iately overlying the too th sur faces should als o includ e sma ll ret en tion loops, to which shou ld be weld ed sma ll patches of stainless s teel mesh. These mesh pa d s are adapted to th e sha pe of the tooth s urface. Returning to the p atient, the buccal sur faces o f the teeth are etched and the wire bonded to them, using a composite ma terial. Un filled res in, s uch as Poly-C or Directon (TP Labo ra tories ), is p robably the ea siest to use, is ad equate for the task, and is easy to rem ove at the conclu sion of the treatmen t. A small custom-mad e hoo k or button is p repa red and bond ed to the une rupted too th, following its exposure. At the sa me visit as these prcce-

dures are pe rform ed , the patient is taug ht to p lace a s mall latex ela stic 0 / 8" med iu m or 5/ 16" light gauge) on the hoo k an d to d raw it round the wire exten sion d istally to the opposing seco nd mo lar an d then forward to engage the small protrusion of the wi re mesial to the first premolar. This for ms an L shaped con figu rat ion to the elas tic, which has a dual p urpose. The overall length p rovid es for a light force of excellent ra nge, while, at the same tim e, making the manipulation of the elastic very easy for the pa tie nt. The vertical traction that is ap plied to the too th may be altered to incl ude a horizontal com po nen t, by altering the po sition of the d istal end of the bond ed wire, thereby also d irecting th e too th mesially, d istally, lingu ally or bu ccally.

IMPLANT ANCHORAGE A successfu l im plant can be used to p rovid e 'absolute' an chorage, since it forms an osseointeg ra ted u nio n with the bone, an d , like an a nkyloscd too th, will no t respond 10 orthod ontic forces (Fig. 8.8). The u se o f implan ts in this manner wou ld ap pear 10 offer co nsiderable promise for the fu ture, par ticul arly for pa rtially denta te ad u lts, and for replacing extra -oral an chorage in non-growing patients (Roberts et al, 1984).

198

THE ORTHO DONTIC TREATMENT OF IMPACTED TEETH

- -- - -- - - - - - -- -- - - - - - - REFERENCES Azaz B, Shteye r A (1 978) Resorption of the crown in impacted maxill ary ca nine . A clinical, radiographic and his tologic st udy. lil t I Gml Sf/rg 7: 167- 71. Fournier A, Turcotte J, Bernard C (1982) O rthod on tic considera tions in the treatme nt of maxillary im pacted canines. A m I Orthod 81: 236-9. Herzer W, Seifert 0, Mahdi Y (1994) Die

kieferorthopadtsche einordnung rctiruertcr eckzahne un ter bcsondcrcr bcruckstch tigu ng des beha ndlungsalters, der angu lation und d er dynamischen okklusion. Fortscnr Kieierort!lop 55: 47-53. Kokich ve, Mathevvs Dr (1993) Surgical and orthodontic managem ent of Impa cted tee th . Dellt eli" N Am 37: 181- 204. Lustmann J, Lewinstein ( 995) In terpositional bo ne g rafting technique to wid en narrow maxillary ridge. 11It J Oral Maxillo/ac Implallts 10: 568-77. Orton H5, Garvey MT, Pea rson MH ( 995) Extrusion of the ectop ic maxillary canine using a lower removabl e applian ce. Alii J Ortlwd 107: 349- 59.

Peck L, Peck 5, At tia Y (1993) Maxillary canine-fi rst premolar transposition, ass ociated den tal anomalies and genetic basis. Angle Grtnod 63: 99-1 09. Richard son 0, Cawood JI ( 991) An terior maxillar y os teop lasty to broade n the narrow maxillary ridge. lilt ] Oral Maxillo/ac Surg 20: 342-8. Roberts WE, Smith RK, Zilberman Y et al (1984) Osseous adaptation to continuous loading o f rigid endosseo us implants. A m J Orthod 86: 95-111. Sailer HF (1989) Two new met hod s co mbi n-

ing osteotomies and cndosseous tita niu m screw impl an ts for the narrow maxillary ridge and the atrophic lat eral mandi ble. In: Proceedings 0/ Third International Congress 011

Preprostnetic Surgery, 'Tile edeniuicus jaw', A rnnem, The Netherlands, 1989, 62-3 (abstl. Simian M, Baldoni M, za ffe D (1992) Jaw bone enlargem ent u sing immed iat e implant pla cement associated with a s plit-erest techn ique and guided tissue regen eration. lilt J Periodent Restor Delli 12: 463-73. Thilandcr B, Jacobson SO ( 968) Local factor s in impaction of maxillary canines. Acta Odont Scand 26: 145-68 .

9 CLEIDOCRANIAL DYSPLASI A

CONTENTS • Clin ic al features and dent al ch aract eri st ic s • Treat ment mo dal ities • Dental c rowdi ng • Retention • The rel at ive merits o f th e di ffer ent ap proaches • Met ho do logy o f t he Jerusalem apcroech • Tr eat me nt exp eri en ce • Pat ient var iat io n

CLINICAL FEATU RES AND DENTAL CHARAC TERISTICS Th e cleidocranial d ysplasia pa tient is typ ically of short stature, wi th a b rachycephalic sku ll a nd bossing of the parietal and frontal bo nes. There is hy poplasia o f the m td face. giving the misleadi ng appeara nce o f mandibula r p rogna thism . The s ku ll su tu res and fonta nelles ex hibit dela yed clos ure and seconda ry centres of ossificatio n occu r in these ar eas, with the formation of worm ia n bo ne s. The development of the clavicl es is defective, and mngcs from a sm all med ial ga p to total ab se nce in se ver e cases (Kallia la and Tasktn en . 1962; Bixler, 1976; Cohen, 1976; Zegnrclli ct al, 1978; Shafe r et nl, 19H3; Tachdjian, 1990; God in et al, 1990). The pa tient usu ally has a narrow ches t and slo ping shou lders . Accord ing to Stewart a nd Presco tt (1976), more th a n 100 other e nomalies ha ve been asso cia ted with these major clin ica l features in the con di tion. The pa late is na rrow a nd occas ionally hig h, an d there is no r mal eruption and nu mber of the d ecid u ou s tee th. Th e permanent molars usually e ru pt la te. but spontaneously, while the re ma ind er of the pe rma nent dentition, i.e.

the successional teet h, exh ibits vc rv dclavcd or non -eru pt ion. Additiona lly , su pe rn u merary teeth develop in the successional teet h areas in numbers tha t typically vary from none to around 12 in general, although the hig hest reco rd ed number ever found wa s 63 (Ya ma mo to et ,11, 1989 ). Apart from barrels haped teeth and the ra re occurrence of pegshaped tee th in the maxillary inci sor a rea only, the supernumerary teeth ta ke the form of premolars in the premola r a rea, canines ill the canine area a nd incis ors in the incisor a rea. They may therefore be more a p propri at ely refe rred to as supp lemental tooth . Cleid ocra nia l dysplasia has an inhe ri tance pa tte rn that is au tosomal domina nt (Zeg arellt et al, 1978), w ith a high incid ence of new m ut a tions a t a rou nd 20-40% of all cases (Shafer PI al, 1983). Se veral of the cases that ha ve been under our care come from families w here a pa ren t was affected, and thu s d iagnosis was usually (but not al wa ys ) mad e at birth . For mo st of the ot he r c.1St.'S, a ten ta tive or init ial d iagnosis was suspected only se veral years la ter, by the child's pocdiatrician or orthopaedist. altho ugh the d iscovery was sometimes mad e a t a dental examtnatio n. Corroborative evidence from a clin ica l

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

~=~=~=======C'_

2OO

examination and a wider radiological examination was then ob tained to es tablish the defin itive di agnosis . During the p hysical examina tion, the clinicia n sho uld set ou t to confirm as many of the featu res described abo ve as poss ible. ' In par· ticula r, the pa tient sho uld be asked to app roximate the shoulders, to confirm the clavi cle anomaly (Fig. 9.1). Palpa tion s hou ld also be mad e of the area be tween the pari etal bones on the crown of the skull an d be tween the frontal bOIlI.'S ,11 the up per forehead/ hairline

region. In both of these midline areas, a smooth and wide hollo w, co ncavity or fu rro w (Fig. 9.2) may be clearly felt, in contrast to the convex contour o f the sku ll of " nor ma l ch ild . Rad iologica l exa mina tion should include views of the clavicles (Fig. 9.3), the fontanelles w hich may be seen on (Figs. 9.4, 9.5), latera l an d postero-a nterior cephalometric films (Fig. 9.5 ), and an initia l pan oramic film of the jaw s (Fig. 9.6). The sig ns and sy mp toms o f the cond ition arc very d istinct, but entirely benign. The y

Figu re 9.1 (a. bl The appro ximated s hou lders o f a cleid ocr an ial d ys plasia pa nent .

Figu re 9.3

Fig u re 9.2 Fron tal midlin e fu rrow

p.lssin~

through th e hair lin e.

Ches t rildi llgr,1ph til show inct,m pll,tl' clavicles.

CLEIDOCRANIAL DYSPLASIA

Figll res 9.4 IlefU and 9.5 (righ t) Th e p..."te rn-a nl~·rior (Idl ) and 1~I c ra l (rig ht) cc phalograms s how abnorma l cra nia l fonn. open fontan elles a nd n u me rous worrn ian bo nes (arrowed).

(a)

(b)

Fig u re 9.6 (a) A I-t-year-old fem ale cleidocra nia l dys plasia pa tien t wi th a fu ll d eciduous d entition an d two ad ditional m,jxill,jry d ecid u ou s incisors. Only one ~'ru pkd (deeply carious) pl'r Illilnen l molar is pr~":".·nl . Th ...rc a rc 23 u neru pted sUJX'rnume rary te...th. in ad di tion 10 l h~' 32 un e ru pted pl'rm
THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

202

- - - - - - - - - - - - - - - - "-------- - - ar c in no way debilitating or progr ess ive, th e patient is not physically or me ntally handi-

ca pped and other body systems are not adversely affected . Treatm en t of the overall medical con d ition is therefore no t advised (Shafer et .11, 1983; Tachd jian, 1990), and its d iag nosis does little more than label the ch ild asa n oddity, The dental aspects o f the condition pa int a wry different pic ture of the se rious ness of the ramifica tions of cleidocra nial dysp lasia, since they affect the face a nd oral structu res . From s tudent to experienced practitioner in the denial profession , an d out o f all p roportion to the rarity of the condition , its clinical featu res are surprisingly well known, again reflect ing its curiosity value rat her than any abili ty on the pa rt of the profession to promote change and co rrection. For ma ny deca des, the profession has stood in awe at the enorrnirv of the dental problems tha t th ese cases p resent, unable to offer sa tisfac tory ans we rs. The denta l characteris tics includ e overretention of the d eciduous d entiti on, noneruption of the pe rmane n t dentition an d the p r('S('nce of many su pe rnumerary tee th. Nevertheless, there is no dental d isco mfort or disturbance. unless the d ecid uous tee th become dec ayed . These tee th arc sma ll relative to the growing face, an d arc not visible below the u pper lip, pa rticula rly when an often-seen an terior o pe n bite is present. The vertical growth of the alveolar proccss cs is genernlly deficien t. w hich leaves the pa tien t w ith a ve ry shallow lab ial and ling ual sulcus in both j.1 W S. Taken toget her, these feat ur es give the patien t an ed entulous ap pcaf<1 nce, which may often be th e pr esen ting symp tom. Given that (a) the child with cleid ocranial d ysplasia has little by way of a ta ngible comp lain t (no pai n, no swelling, no d ifficulty in fun ctioning), ye t (b ) the dentis t has d iag nosed a benign con d ition of ex traordi nary therap eu tic magnitude, (c) the d entist 11<15 no ava ilable gu idel ines on ho w to even begi n to approach the resolution of the enormity of the p roblem,

(d) trea tmen t resu lts are im possib le to pred ict for someone who has never before seen such a case, and (e) the d egr ee o f facial d eformity is usua lly of ins u fficient consequence to demand surg ical mod ifica tion, it is entirely understanda ble that a respons ible clinician will hesitate before undertaking treatme nt. The alternati ves arc (a) not to offer treatment at all, (b) to suggest the more rad ical approach of ext raction of many teeth. followed by prosthetic replacement, or (c) to advise an orthodontic-surgical treatment procedure, with an unknown level of confidence in its result. However, non-treatment becomes less of an option as the patient grows older. Because of considerable occlusal attri tion and caries, there is .1 progressive mo rbidi ty of the decid uous den titio n, which sta rts in the early teen s and ga thers momentum over just a few years. Roo t canal treat ment is often need ed , and res toration becomes di fficu lt. The patient's ap pea rance su ffers still furt he r. with a red uced lower face height (Smylski et al. 1974), impaired masticatory func tion, and con tinuing facial growth contributing to the increasing cverclosed appearance. Treatment is needed to provid e a n efficient masticatory appara tu s, and imp rovem ent s in the den tal appear ance and the facia l proportions.

TREATMENT MODALITI ES These go als may be realized in several wa ys. The recommen ded meth ods that have been propose d o ver the period of many ye,l rs have m ost ofte n reflected the particu lar area of dentistry in whic h the treating de ntis t has specialized. The refor e, to a d egr ee. the mode of treatment may depend u pon wh ose d oor the pa tien t first knocks!

CL EIDOCR ANIAL DYSPLAS IA

Removable prostheses The most popular a pproach ha s been to p rovid e th e patien t w ith removable pa rtia l or full prostheses , w hich fu lfils all the im m ediate needs of the pat ient. Th is approach has been sugges ted by m a ny only af te r th e re moval of all the d ec iduous tee th and the uneru pted supe rn um er a ry and perma nent teeth (Winther a nd Kha n, 1972; Kellv and Nakamoto, 1974; Yam ..r moto c t al , 1989f Give n th at the alveo la r bone height in these cases is very lim ited, w ith s hallow sulci, the dentist s hould ponde r th e construction of replacement tissue-borne pros th eses 10 yea rs la te r. after ad di tiona l a nd ia troge nic ridge resorption has occurred . The absen ce of alve ola r bon e and th e thi nness of th e mandible itself w ill ru le o u t the use of implan ts. Others have ad vised ret aining the standing teet h an d the constru ction of p ros theses around th em (Fro m m er and Lal'eyrolerie, 1964; H ilch in a nd Fairley, 1974; Ke lly and Nakamoto, 1974; Ste wa r t a nd Pres cott, 1976). A fu rthe r refinemen t recom m en d s th e e xploita tion of any standing tee th. togethe r w ith the su rgical exposure of unerupted tee th , to se rve as su pports for an overdentu re (H itchin and Fa irley. 1974; Weintra ub and Yasilove, 1978; Probs ter et al, 1991). By m a king it tooth -bo rn e, th e de nture is less likely to cause fur the r rid ge res o rption, but the sup-porting tee th w ill d ete riora te q uickly under th ese circumsta nces, both from ca ries o f the crown and th e root sur faces and from loss of pe riod on ta l a ttac hm e nt.

Surgical relocation In the search for a no n- prosthetic m et hod tha t utilizes the e xisting teeth, su rgical re moval of the s upe rn u me ra ry teeth, follo wed by ca reful dissection of th e une ru pted tee th a nd thei r repositioning or tra nsplanta tion in to artificially pre pa red sockets , has been p roposed (M uller, 1967; Oksala and Fa gerstrom, 1971; Shafer e t al , 1983). H owe ver, these stud ies do not appear to have been reported o n following lo ng-te rm o bserva tion, and one is left to

pres ume th at the tr ans posed teeth will , in tim e, und ergo fairly rapid pa thologic root resorption, as seen with other tra nsplant ed tee th. These methods all suffer one serious drawback, namely tha t the results thus achieved deterio rate in time a nd thei r p rognosis is re latively poo r. When one considers th at treatment for the co ndi tion is requ ired in the pa tie nt' s sec o nd or thi rd d ecade of life, these m oda lities m ust be co ns ide red to be of lim ited value a nd essentia lly inad eq ua te to the task.

Orthodontics and surgery Befo re the mid -1960s, w hile som e limited positive res ults we re obtained with o rthodontics, th e id ea W ,1 5 co nsi d e red to be impract ica l and fanciful, and was w id ely d erided . Ne vertheless, it caught the im agi na tio n of several clinicia ns, and , pa rticul a rly in the lat e 197Q:.; and ea rly 1980s, several publica tions appeared advocating a surgical a nd o rt hodontic m ethod . The meth od used to bring about th e eruption of the tee th was to ex tract th e dcciduous teeth . su rgically remove the u nerupted supemumer.1ry tee th and ex pose the buried pe rmanent tee th, w ith or w itho ut the use of a su rgica l pack. depend ing o n the depth of the ind ivid ual tee th w ithin the ti ssues (Eloma a and Elornaa, 1967; Smylski et al. 1974; H a ll and Hvland, 1978; Frn rnc a nd Eva ns, 1989). • The pa tient wa s th e n seen in routine follow-up visits. until th e teeth erupted o r ha d reached a su fficie ntly accessible po sition. occl usa l to tilt' he ele d gingiva l tissues, for th e a pplication of o rthod on tic ba nd s or bon d ed attachments. In othe r words. assisted t.'rup4 tio n w as o nly p rov id ed for tho se teet h th at had already pa r tia lly e ru p ted. Fo r these cases, char..actenzcd as they a rc by a lesse ned p<)\,,' er of eru pt io n, ma ny mon ths w ill pa ss befo re teeth a p pe ar, a nd so me of the more deeply sited tee th m a y never erupt. Ad d itional su rgical expos ure is needed for some of these, but still with no guarantee of success. Im med ia te bond ing and ligatio n a t the time

204

THE ORTHODONTIC TREATMEN T OF IMPACTED TEETH

- - - - - - - - - - - - - - - - - - - - -of surgery for th ese cases w as introd uced in the litera tu re in the 19805, wh en Tr imble et al (1982) and Dav ies et al (1987) each she w ed a single case in which th is was done. The

advantage of being able to ap ply forces to the most intractably im pacted teeth is well illustra ted in these two cast'S. The results a nd p rogno sis tha t ma y be ach ieved by a method involving su rgical removal of the unwa nted decid uou s a nd su pe rn u me ra ry tee th, follow ed by the orthod onticall y assisted eruption and a lignment of the na tu ral pe rmanen t tee th, m ust be viewed as w arra nting exploitat ion. Wha t, after all, cou ld be better than to res tore the de nt ition w ith the pa tien t' s own tee th a nd with no rma l alveo lar bone su ppor t, through the med iu m o f a healthy pe rtodoutal Hgem ent? Since the orthod ont ic literatu re records few a tte m pts to s tandard ize orthodon tic trea tme nt stra tegy, be yond the a bov e-me ntio ned single case reports, it m us t be conclud ed. tha t the orthod ontic option is not exercis ed for ma ny cases a nd tha t ther e sccrn to be few centres aro und the w orld w here a significa nt grou p of pa tients of a ny size has been trea ted . For these reaso ns, the present sta te of opinion regard ing recommend ed or approp ria te p roced ure is diffi cult to asses s nccu ratelv. Nevertheless, within this mod ality, three d ifferen t courses of action ha ve been s ug ges ted o ver the past few years, each based on the experience of the trea tment of several cases an d each w ith its own rela tive merits. These w ill be refe rr ed to as : • the To ronto-Melbo u rn e ap proach; • the Belfast-H amburg approach: • the Jerusalem ap proach .

degree o f root de velopment of the pe rma nent tee th d ictat ing the timing of eac h s tage. Thus, initially, the d eciduous inciso r tee th a re extracted a t 6 yea rs of age, followed by the deciduous ca nines an d molars at 9-10 years. Supernumerary teeth overlying the crypts of the u ne ru pted pe rm a ne nt tee th a re removed together wi th 'subs ta ntial amou nts of bo ne to uncover the crowns (of the pe rma* nent tee th) to their ma ximum d ia mete r' . The tee th a rc left w id ely exp osed . The Melbourn e tea m prefe rs to expose the incisors a t a se pare te an d add itional su rgi cal episode, an d this is don e after the first m ola r bands a re placed , followi ng th e late eruption of these tee th, which may reach full expression only a t about the age of 10- 11 years. Su rgical pa cks are used to maintain the pa tency of th e surgical e xposur e and to safegu ard access for eventual bo nd ing of the teeth. The e xpecta tio n is that , follow ing the re moval of the obstructive elements, i.e. the decid uo us a nd su pe rn u mera ry tee th, together with a liberal amount of bo ne a nd so ft tissu e, the teeth w ill then eru pt 'und er their own stea m' to a varying d egree an d ove r a n extended time frame. Whe n convenient, orthodontic brackets a re bo nded to in d ividual tee th, a nd these a re d raw n to a light a rchw ire, which s pa ns the unsupported premola r / ca nine a reas, from the ba nded mola rs to one or mo re a nte riorly erupted inciso rs . Teeth are then d rawn to the a rch wire, de pen d in g on thei r becoming accessible to bracket bond in g. Smy lski et al (1974) a nd H all a nd Hyland (1978) d o no t propose a ny specia l o r purposed esigned a ppliances to deal w ith the ver tical traction that is nee d ed in every Mea of the mouth, bu t ap pear to rely on the employ ment of conv en tional method s used in routine orthod on tic trea tment.

THETORONTO-MELBOURNE APPROACH This me thod was origbw ted by a tea m from Toronto tSrnvlski et al. 1974) an d w as la te r furt her de veloped in Melbourne (Hall and Hyla nd , 1978). Surgical p rocedures a re perfo rmed in a stage-by-stage se ries, under endotrachea l general a naesthesia, w ith the

Limitations In this method, the pa tien t is under trea tment for man y years, beginning a t a very ea rly age and requiring several recom me nded a nd fairl y exte ns ive surgi cal in te rve nt ions, f01 -

CLEIDOCRANIAL DYSPLASIA

lowed bv several smaller ones for ind ividual tee th. The ag e of the pa tient in the ea rly stag es a nd the 5COPC of the su rgery are the major deter minants as to wh et he r these need to be ca rried ou t und er ge ne ra l an aest heti c. The decid uous anter ior te..-eth ar e removed at an early s tage, in ord er to encou rage the eru ptio n of pe rma nent inciso rs. Nevertheless, in their subseq uent reco mmen da tion to fu lly expose the pe rm anent incisor teeth in a di stinct an d separate surgical s tage. Smylski et al (974) and I iall and Hyland (978) recognize that s po ntaneous eru ption does not always occ u r. This mea ns that the patient is anteriorly ed en tul ou s for some consi derable time. Th is wo uld see m a high price to pay for what ma y be undue optimis m rega rding the po tential in cleidocranial d ysplasia for norm al erupti on. In two of the three cases d escribed in Smy lski ct al (974), unerupted supern umerary teeth were not prese nt in the anterior seg me nts, and th e pe rm anen t inciso r tee th responded to sim p le exposure an d pa cking. Ho we ver, there arc ma ny caSC5 w here spontancous eruption docs not occu r, this being one of the d iag nostic crite ria of the cond ition, w hich ma y be associ ated specifically with the frequent pr esence of su pe rnu me rary tee th in this region . The placement of attachme nts to the dee ply sited perma nen t teeth is not perform ed at the lime of surgery, but only so me time later , after fu ll healing (by secondary intent ion) has occurred and the su rg ical pack s have been removed . Thu s, at each su rgical stage, valu able time is lost between the exposure an d the force application needed to encourage th e eruption of the teet h .

THE BELFAST-HAMBURG APPROACH Simul taneo usly, bu t qui te independen tly. Richardson and Swinson (1987) of Belfast and Bchlfelt (1987) o f Ham bur g p roposed. a d iametr icall y opposite method of treatm en t of cleid ocranial d ys pla sia . They recognized that, w hile there is the need for ex tensive surgery in th ese cases, th is cou ld a ll be com pleted at one time, includ ing the extract ion of all decid-

uous and supernumerar y teeth and the exposure of all u neru pt ed pe rmane nt teet h . This is carried ou t un d er general anaesthesia, u nd er opcrntmg theatre cond itions and with surgical packs p laced over the remaining teeth to encou rage epithe lializa tion of the exposed tissue, which is the ess ence of healing by second ary inten tion. Du ring the succeed ing weeks, these s urgical packs rema in in p lace an d pe rha ps changed over a further s hortish pe riod , un til brackets ma y be co nve nie ntly bond ed to the exposed teeth-This ca n the n be done under what the proponents consider to be mo re reliable cond itions for bonding than those p resent during the surgical proced ure. Wheth er or not eruption of these teeth occurs witho ut assist ance is the subject of so me d eba te, with one source insisting that, while th ere is apparent improvemen t, this is due to the radi cal lov, of surround ing soft and hard tissu e during the surgical procedure, ra ther than actu al vertical d en tal change (Miller et al, 1978). Nevertheless. even with the most favou rable an d optimistic ass essment, the re can be no doubt that the erup tion \..-ill be ne ithe r suf ficien t no r reliab le en ou g h to eliminate the need for extr usive mechanics. As w ith the Toron to-Melbou rne ap pro ach, appliances con sist of mo lar bands an d bond ed br ackets, with long Sp.l0S of u nsu pported and relati vely fine nrr hwi re used to vertically develop the pa rtiall y erupted teeth.

Limitations By recommen d ing all extrnctton s and exposures at one time, the Belfast- Hamburg surgical policy has clear adva ntages from the patient's point o f view, although a balance has to be s tru ck in terms of timing this prnce~ dure. The earlier-developing pe rmanen t teeth (particu larly the inciso rs) shou ld not be exposed too late in their develo pment to lost' ,my eru p tive po tential tha t they may hove, wh ile th e later-d evelo pin g teeth shou ld not be exposed too ea rly wh ile thei r roo ts are insufficien tly d eveloped . Acco rd ing ly, the Belfast team (Richards on and Swinson , 1987)

206

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

- - -- - - - - - - - - - - - - - -- - - reco mme nds tha t the one- time, comprehen sive, su rg ical interven tion be performe d at age 12-14 years. The immed iate ad van tage of this po licy is \'Cry clea r and encourag ing. although its drawba cks Me of cons ide rable consequence .101.1 not so obvi ou s. By d elaying treatmen t until this I.He age, the teet h of the normal se ries will ha ve bee n held d eep dow n in basa l bo ne by the supernumerary tee th, partirularlv in the latera l incisor/ can ine/premolar area, for an extended period of time . Their roo ts will have reached an ad vanced stag e of develop me n t in these cram ped circumstances, which is likely to exaggerate the existing tendcncv for ,1 st u nted. tortuous and d istorted root morpho logy (becker and Shoc hat, 1982). Remova l of the unwanted ext ra tee th at this late stage will relie ve the impac tion of the pe rmanent teeth o f the normal series, but it will do ~l at ,1 time when thev exhibit even less potentia l for sponta neo us 'eru p tion, pa rticularly in th e incisor region, since th e roo t apio.-s . will already have been com pleted. Du rin g growth in a normal child and with the eru ption of perma ne nt tee th, the vertical developmen t of the alveola r processes that occu rs makes .1 signi fican t con tribu tion to the heig ht of 11ll' lower face. It also leads to the es tablish me nt of d eep ves tibular and lingual sulci, with a clear d ifferentiation o f wid e zo nes of or al m ucosa and a ttached g ingiva . In the un treated cleid ocranial d ysplasia patient, ve rtica l grow th of the alveol ar bone ap pears to be mar ked ly d im inished . Th is brings about the typ icall y red uced hei ght of the low er th ird of the face that is so freq ue ntly a feature o f the cond ition. Thu s, with the late remova l o f the un wan ted d eciduous and supernumerar y teet h at ,1 time when most of the patient' s gro wth has already occu rr ed, the ultima te ver tical al veola r growth that accompanies th e erupti ng pe rmanen t teeth will be cor res pondingly less, leavi ng a shallower su lcus, an absence or red uced w id th o f attached gingiva and an inco mpletely vertically devel oped lower th ird of the face. in the final an alysis. Furthermore, and in add ition to removing the un wa nted supernu mera ry teeth, it is neeess.uy h i g,lin access to the cani ne and premolar teeth of the no rmal series an d to expose

them widely. Wh en the proced ure is p erfor med at this late stage, these target teeth are very d ee ply si tua ted, often with their d eveloping root apices close to the lower border of the mand ible. Th is necess itates the removal of con side rable quant ities o f bo ne (Smylski et al, 1974) an d , as reco mme nded by seve ral au thors, the placement o f a surgical pack over and aroun d the crowns an d necks o f the teeth to prevent bon y healing-over and to en courage spontaneous eruption. This packing p rocedure w ill ma rkedly delay heali ng, an d is desig ned to prevent the reparat ive filling-in of bone. It is d ifficu lt u nd er these circumstances to avoi d pushing the pack into the area of the eEJ, whic h will inevi tably lead to a poo r periodonta l prognos is for the finally erupted tooth, with an exposed eEj and lessened bone sup port IKohav i ct at 1984). The frequ en t need to cha nge packs ove r a long period incurs pain, d iscomfort an d nu isance, d ifficu lty in maintainin g oral hyg iene, and a lim itation of nor mal function, with a long-term bad tast e an d od our in the mou th due to the unhygien ic circumstances. From the su rgeo n's point of view , thi s entails see ing the pa tient for many time-con su ming appointments. There is no active encourag ement of eruption un til bra ckets may be success fully bon ded an d traction ap plied. in a case alread y afflicted by slow or nun-eruption as a characteris tic of the disease. Thu s, at an age whe n facial appei'ITalKC is very important , the pa tient will s pend an una ccep tably long time w ithout tee th. Fur ther more, bon e regen eration will have been slowed down by the u se of a method involving heali ng by second ary intention (Ho we, 1971). Eru pt ion is thu s de layed and a gro wing ove r of the soft tissues, to re-cover the deeper and newly exposed teeth, mily still occur. It becomes clea r that su rg ical policy is gov erned by the w illingness of the operators to place at tachmen ts at the time of surgery. Witho ut them , access to the unerupted teeth must be guaran teed by the s urgeo n performing wide opening and rad ical bone resection, with the placement o f surgical pecks. With them, a co nservative s u rgical policy is po ss ible - on ly enou g h bo ne is rem oved to allo w access for till' placement of a smal l eyelet

r

CLEIDOC RAN IAL DYSPLASIA

attachm ent on the minimall y exposed too th surfa ce. The surge ry may then be a imed at p n..-scrving ra ther than removing bone, since the prese nce of bo ne docs not seem to hi nd er mechanically enco u raged eruption of the tee th in these cases. Its lac k wou ld be a greater drav v ba ck in ter ms of the even tual degree of bo ne s upport and th us of the periodont al prog nos is o f the e ru pted teeth

(d) a ttending to the p at ien t's psych ological well-being by focu sing the earliest s tages of trea tment to the resol ution of the inciso r im pa ctions.

(Ka h ilvi ('I a l, 19$-1). It has bee n reported (Srnyls ki e t al, 197-1-)

Cleid ocranial dysplasia pa tients ex hibit each of the follow in g fea tu res to a va ria ble degree:

that denser alveolar bo ne is p res en t in cleidocranial dysp las ia. We have not fou nd abnormal bo ne in any of the cases in our care, although the observer could understandably be mi sled bv the fact tha t cortica l bone is found, to the relative excl usion of spongiosu m . It should be remembered that th e impaction of many tee th within the ~lWS takes u p m uch of the volume within the body of the ma nd ible w he re spongiosum wo uld normally be p rese n t. Thus, while cortical bone encompasses all these tee th an d is p resent in norm al amou nts, sponglos u m is s parse.

THE JERUSALEM APPROAC H This method Wec ker ct al. 1997a,b) was presented for the firs t time at the sa me forum as the Belf ast-Hambu rg a p proach, d escribed a bove (Becke r an d Shteye r, 1987). Its mod us ope ra ndi is quite d ifferent from either of the two earlier a pproaches. The Jeru salem approach is based on a rationale tha t is rela ted to the abnor mal d ental de velo pmen t of the pa tient a nd on the factors that produc e it. Th is cornprchc nsive ap p roach to treat men t ad dresses the follow ing po ints: (a) a recogni tion of the clin ical feat ures of the

facia l, oral and dento-alveo lar s tr uctures in the d isease; (b) the s urgical measu res that are required to provide access to the areas con cern ed; (c) the need for a n or thod ontic stra tegy to enable the applica tion of extrusi ve mech a n ics to the buri e-ci teeth in a n efficient a nd reliab le ma nn er:

Clinical features

(a) non-resorption of deciduou s tee th roots; (b) presence of su pe rn u me ra ry tee th. ma r kedly d isplacing the d eve loping pt.. rmancnt teeth a nd providing a physical barrier to their eruption; (c) lesse ned eruptive fo rce, altho ugh eruptive movements arc e vid ent; (d ) poor vertical d evel opment of alveolar bo ne , as w itnessed by a shallow sulcus, ,1 red uced heig ht o f the lower Ieee an d a Class III skeleta l tendency, due to an und erdeveloped maxilla and to a counterclockwise ma nd ib ula r rota tio n; (e) lat e bu t normal and un hi nd ered eru ption of first a nd , so metimes, second permanent mola rs in bot h a rches : (0 . la te d enta l devel opm e nt, as jud ged by the roo t d evelop me nt of the pe rma nent tee th, w hether erupted or u ne rup ted - a 12yea r-old patien t will typically show a d e ntal ag e m or e a pprop ria te to that of a 9 year old (H all a nd H yla nd, 1975; Becke r et al , 1997b; Scow a nd H ertzber g. 1995).

Surg ical therap eutic measures The timing regard ing the actual exposu re of the perm anen t teet h is critical, a nd only tw o in ter ventio ns a re plan ned a t d is tin ct po int s in time, dependin g u pon the exten t of roo t d evelop ment, as follows. Inte rve ntion 1 A t the de ntal ag e of 7-8 years, the anterior deciduou s tee th, toge ther w ith all the supe r· nu mcra ry teeth, in both the a nte rior an d

2D8

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ~====:..::::===_===_=::_:

posterior ar eas, arc ext ract ed . The anterior pe rmanent tee th, w ho se roots a rc su fficiently developed (two-thirds th eir expected len gth) a rt' su rgically e xposed. a ttachmen ts are

closure (Bec ke r a nd Zi lbcrma n, 1978; Becker e t .11, 1983; Koh avi e t at 1984; Vermette c t al , 1995).

placed immedi ately and flaps fully d osed .

Immed iately following the first int er vention, it becomes necessary to supplement the eruptive force of the incisors. In this way, the vertical migration of the tee th tha t rapid ly occ u rs brings w ith it a p ronoun ced vertical d e velopmen t of the alveola r bo ne (Smylskt et .11, 1974). Thi s is all planned w he n mot d e velop me nt is be tw ee n half a nd thn..ee-quartcrs, w hich corr esponds to the stage o f de velopment a t w hich teeth norm ally eru pt (Cron, 1962), Simi la rly, occlusally directed forces are appli ed to the p osterior teet h im media tely following the secon d intervention.

Give n the usua l lat enes s in develo pment of the de nti tion in these cases, the chrono logical age o f the pa tient a t this stage is u sually around 10-12 years. At this time, the pos terior pe rmanent tee th a rc ,11 an early sta ge of develop ment, with their root s less tha n half their e xpec ted fina l le ngth. The su rgica l intervcnt ion in the p rem olar/ cani ne region is therefore lim ited to remov al of su pern u mera ry tee th . Ac tual exposu re of the developme ntally immature posteri or teeth of the per ma nen t series is not und ert ak en, and their den ta l follicles are left in ta ct until a la te r time. Intervention 2

Th e d ental age of 10- 11 ye.us (chron ological ag e 13+ years) is the most a pp ropria te time for the second interve ntion , because the roo t d evelopment o f th e poster ior successional tee th w ill be sufflclentlv we ll advanced. a nd eruption a nd alignment of the in ciso r teeth will have been achieved. Thi s intervention Involves the e xposu re of the teet h in the can ine /premolar reg ions a nd the im mediate placement of ort hod ontic a ttac hments. The s pecial req u irements of the su rgical proc edure rela te to the conservati on of bone in gcnc ml a nd of the co rtical port of the bone in pa rticula r. Remova l o f the unerup ted supernumera ry teeth with a mi nim u m o f buccal pla te of bo ne crea tes e nough space around the crowns of the im pa cted pe r ma nent tee th of the normal ser ies to allo w the im medi a te bon d ing of attachments. The ling ual plate is left in ta ct and at its orig inal hei gh t. Max illary secon d p remolars milY req uire a pala ta l a pproach, in \...hich case the buccal p late is left intact. Libe ral soft tissue e xpo su re of the surgical field is advised, to enable good vision and access and to help in maintaining the con se r vatwc a ttit u de to the removal of bone. The muco-periosteal flaps a re finally re placed inta ct an d sutured bac k, withou t the use of packs, in the ma nne r of p rimary soft-tis sue

Orthodontic requirements In the broad overvie w, the prov ision o f space w ithi n th e arch is made by appliancege nerated an tero-posterior expa nsion of postenor-versus-a nte rior erupted teeth (Elomaa a nd Elornaa . 1967), w hile th e re moval of deciduous and supernumerary teet h provides space in the ve rtical pla ne. In this way. and w hile s pace is bei ng pro vided, se lf-re alizatio n of any eruptive po te ntial that the pe rm a ne nt teeth may possess is pe rmitted , to present the opportu nity fo r them to mi grat e towa rds the occlus al pla ne an d to ta ke u p a more norm al de velopmenta l position wi thin the alveolus. This seems to occur to a varying d egree, to allow the roots to develop in un cr amped circu msta nces a nd thereby lead to the acqu isition o f a more normal root mo rp ho logy (Becker an d Shocha r, 1982). Ho wev er, it is im portan t to em p hasize that no reliance is placed on s ponta neous eruptio n of these tee th (Sm ylski e t al, 1974) althou gh. sho uld th is occu r, it is on ly to be wel comed an d w ill simplify the trea tm en t p lan . Howe ver, the Je ru sa lem approach has been form ula ted to com bat the wors t eventuality, i.e. noneru p tion. From the point of view of the orthodontic mechanothera py, achieving efficient force application in an appro p ria te di rection for

• C LEIDOCRA NIAL DYSPLASIA

ea ch too th requires examination of the follow Ing poin ts. (a) There mu st be a su fficient number of erupted an cho r teeth in th e mou th to act as a base fro m w h ich forces m ay be

generated . As we have already pointed o u t, the pe rmane nt m olars usually e ru p t

without help, e nd one or two incisors may also be visible. (b) One has to design a rigid app liance frame th a t w ill e ndure chewing and ot her functional and parafu nctio nal m oveme nts tha t may be ex pected to occur during everyday o ral fu nction. considering the long spans o f free. unattached and un protected archwire, mesial to the few erupted anchor molar teeth. (c) Ind ivid ua l a nd groups of u neru pted tee th must be subjected to ligh t continuous forces. (d ) Appliance d es ign has to feature su fficien t versatility to enable it (1 ) to app ly ve rtical e xtru sive forces to e ru pt the impa cted tee th ra p id ly; (2) to open s paces between recently eru pted tee th, to p rov ide room for oth e r unerup ted tee th a nd to es ta blish interpro ximal co ntacts and a rch form; (3) to bri ng these tee th into occl u sion a nd to u p righ t th e ir roots a nd all th is w ith only m inor alter ati ons!

The pa tient's psycholog ical well-being In Cha p te r 5, we poin ted out th at it is inadmi ssible to leave e ven th e yo ungest pa tient w ithou t fron t teeth for an exte nd ed pe riod of tim e, a nd that it is im portant to make th e child aw are tha t effor ts a rc bei ng m ad e to rectify suc h a situa tion speedily . The physical obst acles to er up tio n (i.c. th e d ecid uous a nd su pernu m era ry teeth) must be re m oved, in orde r to faci lita te th e eruptio n of the a nter ior teeth. Proper tim ing is crit ica l. This s ho uld only be done a t th e age when the perma nen t incisor tee th indica te adequa te roo t d e velop-

rnent fo r er u pti o n and only when an a ppliance is in p lace, to actively sup p lem ent their lim ited e ruptio n .

DENTAL C ROWDING Whe n st udying the radiographs of a n u ntr eated cleidocran ial dys plas ia pa tie nt, one is im media tely stru ck by the Intra-bony crowding p rovid ed by the la rge nu mber of unerupted pe rmane nt tee th (those of the normal se ries a nd the su per n u m er ar ies). During surgery and after all o f th e superfluou s d eciduous and su pe rnu m era ry teeth have been re m oved, the surgeon a nd th e o rthodontist will view the open su rgica l field , and . given the rel ati vely un der-d eveloped a lveolar p rocesses, w ill find it d ifficu lt to sec how it is possible to fit all the rem a in in g permanent tee th in to the d e nt al arch a nd in fu ll alignment. On th e basis of th is 's po t' d iagnos is, th e o rthodont ist w ill be tempted to advise the o ral surgeon to ta ke adva n tage of th e p revailing general a naest hetic to re move a p re mola r tooth in each q uadrant of th e mo uth, in w hat would appear to be a log ica l step neces sa ry to red uce th e appare nt crowding. Ho we ver, for most cas es, this step wou ld be regre tted la ter w he n th e subseq uent s ize and fo rm of the alveo lar proc ..-sscs, w hich m ay be d eveloped as a by- produ ct of the m echa ni cal eruptio n of the tee th, become ev id en t. Initi ally, th e ap plia nce-generated eru p tion of the anteri or teeth b rings the teet h int o the mouth, with a p ro nounced lingua l tipp in g of their lo ng axes. Th is is due to th e influence of purely vertica l forces th at will have been bro ugh t to bear on th e per manent incisors, whose d evelopmental po sition is very much lin gua lly p laced and apica l to the recently ex tracted d eciduous inciso rs. Fo r this reason, th e pe r ma ne nt incisors must be tipped labi a lly, to crea te a no rmal arch for m and to provide a m o re procumbent su pport fo r th e lip s. This w ill contribute much ad d itio nal space in the dent a l a rches for th e prem ola r a nd ca nine teeth, a nd will be instru me nt a l in s ignifica ntly elimina ting th e

210

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-

-

denta l crowd ing and the pa tien t's ed entulous ap pearance. It is only after comple te or almost comp lete eru ption has occurred that a decision shoul d be mad e as to whether extractions ar e need ed . Our limited experience h..as shown tha i, in thes e younger pa tients. extractions are not needed in the final analysis a nd that ad equa te spa ce for alignme nt o f ,111 the teeth a nterior to the first molars ma y easily be provided .

RETENTION OF THE TREATED RESULT Once the permanent teeth have all reac hed their fina l posi tions in the arch , the removal of the fixed appliances will not u su ally be accompanied by a los s of ve rtica l heig ht of these teeth, desp ite the fact tha t their ver tical positions will have cha nged. so d rastically over the trea tme nt period . Th e lat eral w idth of the two arches w ill have been se t initia lly by the first perma nent mola rs an d the overretained d ec id uou s teeth. Th e usc of fixed lingual a rches d u ring trea tmen t will have allowed goo d co ntrol aga ins t any cha nge in this d imension. The refore the orthod on tist ma y con fidently expe ct no na tural po sttrea tme nt alterati on of the a rch w idth. The on ly d ilemma s of a ny conseque nce in the co ntext of ret e ntion relate to the la biolingual post-trea tme nt posit ion of the in cisors of both ja ws an d to those teeth tha t ha ve u nde rgon e rota tion al orthodontic mov ement during trea tme nt. It is a xiomatic to sa y that proper lab iolingual po sitionin g o f the a nterior teeth in any pa tient is de pe nde nt on the m uscula r balance betwee n th e lips an d the tongue. Tee th placed too far labially or lingually w ill inev ita bly be push ed by the lips o r to ng ue in the opposite direction, when all retaining d evi ces a rc remo ved . Du ring the o rthod ontic trea tment of the nor ma l pa tie nt and in the interests of stab ility, the po sition s of ad jace nt teet h are often used as a yardstick to w hich the d isplaced tee th sho uld be mo ved to achieve the desired alignment. A lternatively, ce phalometric sta nda rds m.1Y be p referred aga inst w hich to com pa re the d ent ition, such as the lowe r

-

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

"-'------'--'-----'-----'-------

in cisal edges vis-a-vis the A-Po line (Ricketts, 1981). Wi th the cleidocra nial dysplasia pa tie nt, there is no scientific w ay to judge the 'biologically correct' a nd theref ore s table position of the incisors. No r a re the re an y pu blished cephalometric d a ta on a la rge gro up of tr ea ted an d po st-re ten tion clei docrania l d ysp lasia pa tients, to hel p es tablish s uch 'n orms'. By no mea ns ma y the ce phalometric va lues of these pa tie nts be co m pa red w ith the a verage val ues found in the various growth s tud ies that have bee n carried out w it h samples of no rmal pa tients. Consequently , the use of H old a wa y or Ricke tts analysis an d a growth p red iction analysis, as p roposed elsewher e (Hall and Hyla nd , 1978). is complete ly in valid an d highly misleading. The orthodontist ca n never be sure of the stability of th e final res ult in this as pect of the tr ea tmen t, and some form of lo ng- term retention will us ua lly be ad vis-

able. Th is be ing so, w e ha ve adopted th e view tha t the incisors should be brought well forward, extruded below the u ppe r lip, to slig h tly over-com pe nsa te to some degree for the years that the pa tie nt has lived w ith very shor t and la rg ely invisible teeth. Wh en only deciduous tee th we re p rese nt, or in the initial stages of trea tment, the pa tien t's so cial interreaction w ith othe rs w ill have bee n d icta ted by a des ire to ma sk the missin g an te rior tee th, a nd he or sh e ma y ha ve ad opted un na tu ral and unsmili ng facial expressions a nd a re tiring a ttitude. O nce the teeth align me nt ha s bee n comple ted and ap pliances rem oved, a posi tive a nd dram atic ps ycholog ical change in pa tients' a ttitud e to life see ms to occur, an d, from then on, many seem to wa lk around w ith a per manen t smi le on their faces, conscious ly an d delibe rat ely d isp lay ing their new -fou nd teet h! After a short period of time w ith con ve ntion al remova ble ret ainers, ou r p ractice has been to p repa rl' a nd ap ply fixed m ultistra nded bon d ed re tainers to the max illary and mandi bular six an ter ior tee th (Z achrisso n, 1977; Bec ker a nd Goultsch in, 19R4; Becker, 1987). These will then hold the labio- lingue l positio ns of all the a nterior teeth, as well as p re ven ting rota tio nal rela pse. The conven-

CLEIDOCRANIAL DYSPLASIA

tiona ! re mo va ble re taine rs m,1y the n be discarded .

THE JERUSALEM APPROA CH IN CLI NICAL PRACTICE Pa tien ts who a re suspected to be suffering from cle id ocranial dysplasia a rc refe rred to u s through d iffere nt ag e ncies, includ ing the various medical s peci alties an d general dental p ractitione rs or d ental specialists. A small p ropor tio n also a rr ive on their own initia tive, requesti ng advice a nd help in the search for a sol u tion to the presence of 'w ry small tee th' or to their 'toothless' appear<1 1l(l' . ln order to firs t confirm that the pati ent docs indeed su ffer from cle idocranial dysplasia, ou r d iagn ostic rou tine has come to include (<1) a clinical exa mina tion in sea rch of the ge ne ral cha racteris tics of the con d itio n, w hich ta kes in the form of the craniu m, the face an d the cla vicles, includ ing the mob ility of the shou lders; (b) a n intra-or al examinati on to rela te the e ru ptio n sta tu s of the d entition vis-a-vis the patient' s chr onologie age; (c) a rad iogra phic evalua tion, w hich p lays a critical role in the con firmat ion of the clinical diagnosis, inclu des a ches t X-ra y a nd a ntero- po ste rior a nd la teral sku ll rad iog ra phs, w hich a rc pe rfor med in a

cephalost at. A t the same time, a panoramic radi ogra ph is stu d ied and su pp lemented with pe riap ical a nd occl usa l views, as required . Once the d iagnos is has been confirmed , genetic counse lling is offered to the parents regarding their own fut ur e o ffsp ring, but more particularly rega rding offspring of the a ffect ed ch ild. A n im po rtant pa r t of the gene ticist's exa m inati on will includ e ga the ring informati on a bout rela tives an d the poss ibility tha t othe r, mo re d ist a nt, fa mily members may be simila rlv affected . Trea tme nt of the con d itio n will [m'olve the ta lents of a team o f three dental specialists. wo rking in close co llabo ra tio n, an d the firs t stage may begin immediately.

Stag e 1: Assuring the health of the dentition Treatment of the cleid ocra nial d ysplasia patient w ill necessita te the wearing of orthodontic applian ces for se veral yea rs. Th erefore an essential requirement in all cases is tha t the health of the d entition be guaran teed by proper oral hygiene ins truc tion, w ith followup to check tha t an ad equate le vel of com plia nce is a ttained . A ppropriate use of fissu re sealants a nd fluoride a p plica tions is recommended . Cariou s teeth w ill need to be trea ted , but , in order for the pa ed odon tist to be in a position to decide on the type of restora tion in dicated . the timin g of the extraction of the rema ining deciduou s teeth w ill need to be d etermi ned a t the ou tset.

Stage 2: Vertical co rrection in the incisor region For most cleidocra nial d ysplasia cases, a t d ental age 7-8 yea rs, a ll firs t permanent mola rs will have erupted . Some times, one or more of the permanent incisors w ill also have eru pted , but the followin g description o f the tech niqu e will assume the lea st fav oura ble ini tial scena rio. Orthodontics

Plain orthodontic band s arc fitted on the eru pted first mola rs (Fig. 9.7), a nd a compound im p ression is ta ken of eac h d ent al arch. The ba nds ar e then ca refully sea ted in the im p ress ion s, and a model Is cas t. Hea vy sold er ed palatal a nd ling ual arche s are prepared on the tw o models, a nd single soldered bu cca l tubes (0.036" round ) a re loca ted running mesially, close tothe buccal s id e o f the decid uo us tee th, parallel to th e occl usal p la ne. A mi sp laced firs t pe rmane nt mo la r may need to be aligned w ith a re mo va ble app lia nce first, in orde r to be ab le to align the bu ccal tu bes accura tely as d esc ribed, since the efficien t wo rking of the a p pli ance d epends on this.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH ~::..::.~==_=__=~=_=__~==_=__

212. Fig u re 9.7

(a) Plain ba nds ha ve been ada pted til the maxillary left seco nd d eciduous molar an d the firs t pt'rm,lnt'nl molars in tbc other th ree <\u,IJ r,m t'i. (b) An upper (shown he re) an d lower compound im pn.."sio ns ,UI' ma de. (el The ba nd s a re remo ved from the mouth a nd carefully Tl.' P1,lCOO in the impression. Th e bands iln" the n p.lrtially filkJ with wax, be fore a mod e l is poured. Cd) The cast model with accurately tocat..-d and stabilized molar bands. Ie! The occlu sal view of the man d ibular model shows right ilnd It'll tubes converging in the mid line and the lingua l ilrch in place. (f) The heavy 'incisorerupting' archwire is slotted intu the molar tubes, "loll' the Seshapcd hoo k soldered in the canine area and the anteriorly soldered fioewi re fra me. (g) Disassembled mandibula r applia nce ready for intra-ora l placement. ( h, i) The appliances cemented in the mouth.

,,)

(b)

'e)

'dl

Ie)

• CLEIDOCRANIAL DYSPLASIA

(Fig u re 9.7

COlll illll,'l1)

Igi

Ihl

(i)

A hea vy 'inciso r-e ru pting' a rchwirc is prepa red for each nrch in ad va nce (Fig. 9.7f), an d its fun ction is to achieve a correction in the ver tical plant'. This archwirc is made of 0.036" rou nd wire, which slots into the buccal molar tub es up to a pr ed ete rmined bayonet bend Oil ea ch side. Th is ho lds the w ire 2- 3 mm labial to the anterior teeth a nd 3-4 mm g ingiv al to the occlusal plane. In the canine area, ,10 Scsha ped hoo k is sold ered , wi th its mcsi..'I Uy pointing extremity on the occlusal side an d the d istally pointing ex trem ity gtngival. In the midline are a, ,1 small fine wire fra me is also sold ered, a nd po ints towa rds the sulc us d ep th . An ' inciso r-alig ning' a rch wire is also prepa red in advance, although it will not be pu t

to usc u nt il all the pe rmane nt incisors ha ve been full y er u p ted . This consists of 0.020" internal-di ameter tube sid e pieces, which free ly slide accu rately into the 0.036" bucc al tubes, without allowing la teral 'p lay ' . The tubes
THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

Surgery The patient is now read y for the first surgical inte rve ntion (Fig. 9.8), a t the completion of w hich the patient will hav e lost all of the anterior d eciduou s tee th a nd w ill also have had the un eru pted supem umerary teeth removed . Fine p igtail ligatur es w ill have been pla ce-t in the eyelet a ttachments bo nded to the inci sor tee th, a nd these w ill be the only link betwee n the invis ible unerupted permanent tee th a nd the exterior (Fig. 9.9). Deciduous tee th not associa ted w ith su pe rn u me rary teeth arc ge ne rally left u ntil the ne xt. su rg ical

stage. Th e s ur gica l flap s are fu lly sutured bac k. Orthodontics Still under the e ndotracheal an aesthesia, in the operating theatre, the p re pared 'inciso rerupting' a rchwtre is p laced in the buccal tubes a nd secu red by dra wing a chain elast ic mod ule be tween the d istal of the bu ccal tu bes to the mesially pointing extre mity of the 5-hook. The a rc hwire is raised with lig ht finge r pressure, an d engag ed by loo p ing the pig-

'bi

en

,
1 .J.y~·.lr ....,ld r.lti~'nt.

(,1-<) In tr.1.....r.l[ views o f initial condition. (Jl

Ant~'rior in tra-ora l

view o f appliances in place.

CLEIDOCRANIAL DYSPLASIA

215

mand ibular archwircs. This 'box elastic' pro vides an intermaxillary vertical force to each archwire. If the midline portion of the stretched elastic is laid over the solde red vertical frame, tissue impingement may be avoided (Fig. 9.10).

tail liga tures around it . Since these pigtails are tied d irectly to the bur ied incisor teeth, this displacement of the archwtre elicits a vertical extruding force on the unerupted teeth (Fig. 9.9c). This force generates a rapid response of the teeth, as witnessed by elonga tion of the pigtail liga tures, over a pe riod of a few weeks. By disp lacing the archwire apically an d then 'rolling up' the pigtail around it, extrusive pressure may be rea pp lied over seve ral visits, until eruption occurs. To support the orthodontic anchorage, a large fine-gauge elastic should be used to engage the distal pointing hooks on each side of the maxillary and

The incisors eru pt relatively quickly and with a strong lingu al inclination , in general. At that

(,)

(h)

Stage 3: Horizontal correction in the incisor region Orthodontics

f igur e 9.9 The same patient as in Fig. ':I,ll. (fl) Four maxillary i ncisors have been expos ed and attachm ents bonded. (bl Six mand ibular anterior teeth haw been expos ed and attachments bonded. The exposed chin bu tton and the lingual arch indicate the depth of these teeth. (c) The 'incisoreru pting' archwirc is repla ced when full-Hap suturing is comple ted, a nd the steel ligatu re pigta il~ Me made to ensna re the arc hwire, w hich h,lSbee n dis placed superiorly by ligh t finger pressu re. (c)

216

THE ORTHODONTIC TREATMEN T OF IMPACTED TEETH

(ill

(b'

Figu re 9.10 The !O<1 me pat ie nt as in Figs. 9.8 an d 9.9. (a) AI 5 weeks post-surgery, d wry light an terior 'boll elastic' is placed on the d ist ally poi nti ng ele ment of th e 5-hooks in the canine a reas to en hance the anchorage. Note the U~ of th e mid line frames to prevent tissue impingeme nt. Cb) Al <;I weeks post-surgery, five incisors have e rupted , an d the arc hwinos have ","-en disengag,"CI to increa-e their deflection. Cd Re-engag ing the a rchwires illu s trat es th eir ra nge o f effectiveness. (0'

point, their eye lets should be replaced by the orthodontic bracket of the or thodontist's choke, w hich should be sit ed in the routine manner (Fig. 9.11). The prepared 'incisor-

aligning' archwire is then tied or pinned into pla ce, whe re its first tas k will be to undertake

the levelling phase of treatment, i.e. incisor height , ro tati on an d , in the edgewise techniques, u prigh ting. With proper buccal tube or ientation at the outset, the long buccal tube side pieces ma in tain the achieved. vertical extru sion, while p roviding resistance to d istortion and stab ility. The light 'box' elas tics

may be attached to the latera l incisor brac kets, to conti nue the vertical extrusive force, if and wh en necessary . As levelling proceeds, the mid d le portion of the 'in cisor-aligning' archwire may be sub stitu ted for heavier and thic ke r wires (Fig. 9.12) until an 0.018/1 or 0.020" w ire is in place, using the sa me side p ieces . At this poi nt , an expand ed coil spring is placed on Ihe side p ieces, which now have a 's top' placed on their mes ial end. When the side pieces are replaced in the bu ccal tubes, the coil sp ring is co mp ressed between the buccal tu be and the

CLEIDOCRANIAL DYSPLASIA

'b)

Figure 9.11 The sa me pa tien t as in Figs 9.8-9.10. Ia-c) At 6.5 mo nths post-sur gery , all inciso rs ha ve eru pted . Con ve ntiona l brackets nave been s ubs titu ted for the eyelet attachments . and the 'inciso r -ali gning archwires are in place. NOll' the extru si ve component genera ted by these a rchw i rl~.

'd

mesial sto p, whic h d isplaces th e ar chwire forward s. The arch wire is tied into th e anterior bracket s under p ressu re. The co mp ressed coil spring is now prod ucing an antero-posterior expansion force, acting between the first molars a nd the incisors . This rapid ly tips the incisors to a more normal labial inclination , enlarging the space for th e unerupted cani ne and prem olar teet h. Archfonn will be greatly enhanced an d the patient' s appearance will , for the first time, beg in to markedly Im prove.

An estima te of treatment time u p to th is poin t (stages 2 and 3), wou ld be between 9 and 18 mo n ths . New rad iogr aphs shou ld now be taken of the u nerupted can ines and p rem olars (Fig. 9.13) to determine the state o f th eir root d evelopmen t and to reassess thei r vertical locatio n w ithin the alveolu s. The absen ce or ea rlier removal of supern umerary teeth in this area, together ,v-ith an increase o f space in the arch and the pa ssage of time, m ay have led to an im provement in their po sition, wh ich should be record ed .

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

218

- - -- - - - - - ----::..::.. -. --=..:. ::-------=-----=------------'------

(b)

(c)

Cd)

Figure 9.12 Th e same pa tivnt as in Figs 9.1'1 -9.11. (a.b) Ail S mont hs post-surgery, 11"" incisor s 1MV<' been moved labially, aligned. and n positive overbite /overjet rela tion s hip has

been establis hed. In th i~ parttrnlar ( "S(', the mand ibular canines were included in this stage of treatment. Noll' the severe mesial mot displa cemen t of these teeth . « ) The occlu sa l vtcw of th e mandibular an terio r teeth indicates

gross labio-Iingua l disp lacement of the roots of the lateral inciso rs and can ines . (d.e) Following 4 months of further trea tm en t, the roo l displacements have bee n corr ected. Thi s was done during a wa iling period for adeq ua te premo la r d evelo p ment, 10 allow the initia tio n of the secon d surgical int ..rvc ntion . Co)

CLEIDOCRAN IAL DYSPLASI A

'bl

Figu re 9.13 The sa me pati e nt as in Figs 9.8-9.12. (a) A pan o ramic view taken 10 mo nt hs P re-surg ery - (b) A sim ilar view 6 months post-surg...ry . (e) A similar view 21 mo nt hs post s urgery. ,oj

Stage 4: Vertica l correction in the posterior reg ion Surge ry

The seco nd s urgical int ervention (Fig. 9.14a) is performed at dent al age 10-11, and it will leave the pa tient devoid of the rem ain ing decid uous teeth. The su rgical f la ps will have been replaced to completely cover the eyel et attachments bonded to the u nerupted pe rm anent teeth , and stainless steel pig tail liga tu res will be visible em anating through the sutured edges of the wound .

Stric tly spea king , the sco pe of this surg ical procedure, poten tially involving 12 tee th (8 p remolars and 4 canines in the fou r quadran ts) is large enough to warra nt endotrachea l anaes thesia and operating theatre cond itions. However, in the more favourable cases, much imp rovement will have occu rre d over the pe riod of tim e since treatm ent wa s origina lly in itiated , and severa l tee t h may have pa rtially erupted. This ma y en courage the oral su rgeon to pr efer to perform the rema ining expos ures under loca l anaes thetic, one or two qu ad rants at a time.

220

_ _

_

_

_

_

_ __

,.J

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

---'--:c==---'--~.:=:_~_'..:.:.:.:::..._.::=

(b J

Figure 9.14

(a) In this pa tien t, the second su rgical interven tion is typically aimed ill exposing and bonding the camnes and premolars in aU fou r q uadrams, Note that onl y a mi nima l ex ~u re of the buccal surfaces v f th tl'Cth is performed. The alveola r bone superior to the te h is left untou ched , as are the e ntire lingu al bo ne a nd th e gin gival a ttachme nts of the extracted decld ueus mola r a nd ca nine teeth. (b,d The bucc al s urgica l flaps ha ve bee n su tured across the ridge to th e lingu al arc h. Elastic thread draws the un e rupted teeth to the ri~id buccal a rms of the 'incisoraligning' a rch wire.

,oJ

Orthodontics

The bu ccal stde pieces are now used as a rigid beam, from which clastic thread may be tied (Figs 9.14b,c) under pressure to the 'rolled up' p igtail ligatures of the un eru pted premolar and canine teeth. Rc-Hgetion will be needed at freq uent int erv als, becau se of the relatively poor range of action of the elastic thread .

Alterna tively, the Johnson-type archwire may be discarded in favo ur of a plain 0.018" or 0.020" arch wi rc, stretchi ng from molar to molar. Its long span, between lateral inc isor an d first molar, is flexible in the ve rtical plane, and the p igta il liga tures may be turn ed

over, to en gage the wir e un der ligh t extrusive tens ion (Figs 9.15a,b). Stage 4 is expected to be completed within 9- 15 mon ths (Fig. 9.16).

Stag e 5: Correction of the axial orientation of the roots of the teeth Orthod ontics

Mesio-distal up righting of the anterior teeth will have already occurred, if ed gewise brackets have been used initially, althoug h roottorqucing moveme n ts will usu ally need to

• CLEIDOCRANIALDYSPLASIA

(il)

(bl

Ftgure 9.15 Ia.b) The same pa tient as in Fig , 9.14: stages in the resol ution of the im paction of the left side carunos a nd premolars, using variou s types of mechanics.

(al

(bl

fi gure 9.16 The same pa tient as in Figs 9.14 a nd 9.15. (a) Panoramic view im mediately prior to second su rgical i n t~'rv~'nli
222

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

- - - - - - - - - - - -- -- -'----- '----- - aw ait the usc of a full rectangu lar arch . With the u sc of Begg brackets, levelling and torqueing au xilia ries may be used du ring stag e 4, once the hea vier w ires arc bein g used in the latter st ages. How eve r. gi ven th e a mou nt of roo l d is placeme nt seen in these cases, it is most likely that stage 5 of the treat me n t will see these movements still being ap plied to the anterio r teeth, while u prighting an d rotating mov em en ts w ill need to be initiated in the premola r/canine regions, following the repl aceme nt o f the eyelets wi th brac kets (Fig. 9_17)_

At this stage, the palatal and lingual heavy arches are no longer needed, an d may be cut off with a high-speed d iamond bur. In the va rious edgewise methods, the mo lar bands \....ill now hav e to be removed in any case, and new bands adapted . with rectangular tubes. Molar expansion or rotation may now be performed , if desired .

TREATMENT EXPERIENCE To date, 16 cleidocrani a l dysplasia patien ts have been treated or are still in the various stages of com prehe nsive orthod on tic /surgical treatment at ou r centre (Figs 9.18 and 9.19) (Becker ct 01 1. 1997b). It is from their trea tment that the Jerusalem approach (Becker et al, 199701 ) has bee n form ulated and refined over the years. Of these cases, th ree had a total absence of supe rn umerary teeth, one of whom had a congenitally missing p rem ola r. Seve n patients ha d fou r supern u me ra ry teeth or less and fou r other s ha d 6, 8, 10 and 23 respectively. Treatment of the rem aining case was initia ted elsewh ere, a nd infor ma tion was not av ailable for him. With th e excep tion of those found in the incisor region, all oth er su pern u merary teet h arc recognizable sup plemen tal teeth, similar to those adjacent to them. Thus su pern um erary teeth in the cani ne and pr emolar regions Me canin ifor m or p remolariform. Barrel-shaped s upern u merary teeth have been the only exception in our sample, and these have all bec-n found in the ma xillary cen tral incisor region . The presence of supple-

me ntal teeth has been help ful in our choice of teeth for extraction, since a d isp laced tooth may be removed an d the be tter-placed ad jacen t tooth aligned in its p lace, without regard to d istinguish ing wh ich is the abnormal too th. Withou t exception, the dent al age of our cases ranged fro m 2.5 to 4 years be hind the chronological age. Spontaneo usly erupted first pe rm anent mol ars have bee n seen in all but two cases, and these exh ibited su pernu merary molar tee th. Unlike other tee th, the pe rm anent molars appear to eru pt spontaneo usly in cleid ocranial d ysplasia, and it seemed reasonable to assume that , in the absence of these obstructions, the molars of these two patients would also have erupted normally. Follow ing the removal of the supernumerary teeth, in both of these cases the unerupted molars were exposed and a su rgical pack pla ced , to encourage hea ling by seco ndary in tention and to maint ain th e pa ten cy of the exposure. The teeth erupted spontaneously after this p repa ratory surgical procedu re, and bo th pa tients were th en tr eated as per the above p rotocol. A single eru pted maxillary firs t p remol ar was present in three pa tients wh ose decid uous p redecessor had ha d an apical abscess . The sh ape of the well-developed permanen t teeth, while clearly recogni zable and classifiable in to their d ifferent too th types, show ed lab ial concavities in the inciso rs, broad mesial an d d istal rid ges on the labi al an d lingual aspect s of both canines and inc isors, an d mesio-d istally excessive and bu cco-lingu ally na rrow p roportions of the lower second p remolars. Th e roots of the successi onal teeth were relatively short, and their axial inclinations were not ne cessarily continuous w ith that of the cro wn , in both th e mesio-d istal an d b ucco-llngua l plan es. This created the need for pe riapica l X-r'1Y monitor ing of the u prigh ting and torque tng movements o f these teet h. In the abov e treat ment p rotocol, th e ability to use interm axillary vertical elas tics on the p rev iously impacted teeth was emphasized. Their valu e is seen in the enhancement o f the eruptive forces to improve ancho rage an d to enco urage vertical alveola r growth. Th erefore

CLEIDOCRANIAL DYSPLASIA

(0)

' d)

(b)

(e)

(0)

(()

Figure 9. 17 (a-d A pat ient in the early part of ~1.lJi:C 5. :\'01" the severe buc(O-li ngu.l] a nd nw"io..d ista l displacement of roots of individ ual teeth . Cd-O St,IJi:C 5 close to completion .

224 _ _ _ _ _ __

_

_

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

----'---::...:...----.::..::..c----'---~="__"__=___=::...:.::::._..

(, )

(d)

(b)

(e )

k)

Figure 9.18 The Mml' ",' t il' nl ,1S in Fig 9.17. Ia-c) At the start (>f treatment. (d-f) At the completion of treatment. Note the tooth size d i«rcp,lncy between the jaws.

225

CLEIDOCRANIAL DYSPLASIA

c.,

eb'

Cd

Figur e 9.19

(a-c) A patien t before lrt'atml'l'll. (<.'1 -0 At 1 year I"lsl-rdl'l'ltiol'l.

226

efficie ncy is no t serv ed by treatin g the mandibular anterior tee th before the maxilla ry a nterio r teeth, merely I:ltX<1USC there is a tim e lapse of a year o r so be tw ee n th e normal eruption times of th ese tee th . The treatment of the an te rior a reas of both ~lWS should beg in at the same time. Neverthe less, it is essential tha t the forces produced by these ve rtica l 'u p-a nd -dow n' clast ics be kept w ithin very mi ni mal values, since the tem ptati on ex ists to use elastics thai a re too s mall an d too thick. Excessive ext rus ive fo rces will br ing a bout ra p id eruption , bu t the clin ical crown length of the erup tin g teeth will be la rge, owing to rela tiv ely lesse r ge nera tion of elveo1M bo ne. The teeth will be ve ry mobile, an d lllay lose their vitality, In the firs t sur gi cal in te rven tion . the ai m is to remove all the supernuml'rary teet h, since these see m to be the principal facto r in the d lsp l..ic crncn t of the ad jacent pe rmane nt teeth more deeply in to basa l bone, The con tinued presence of these extra tee th w ill p reve nt the tee th of the normal series fro m exp ressing w ha t litt le e ru ptive potential they ma y have, a nd hence im portance is a ttached to ea rly re moval . Th is is not felt to be th e sa me for the deciduous tee th , O ur experience has been that, w hen su pernumerary tee th a rc not present in certain areas, the norm al perma nen t tee th in those areas a rc not severelv d isplaced. and, w hile they may still not- erupt spontaneous ly. their de velop me nt is fai rly no rmal. Occasiona lly, their p resence may stim ula te the shedding of the d eciduous predecessor, and they m..ay. in time , erupt. For this reason, in those areas w he re su pern u merary teeth Me not found , d ecid uous tee th arc not remo ved in the first surg ical interven tion . Trauma to d eveloping teet h has been shovvn to cause damage to bo th d evel opin g roo ts an d the enamel of their com p leted crowns (Bnn et al. 19R4; Be n Bassa t e t al , 1985; Zilbcrm a n et al. 1986), Norma l d evelop ment and ma ximum eruption po te ntial a re probably bes t realized w hen the integrity of the dental follicles is maintained , until two-thirds to three-quarter s of the root length has developed . For th ese reaso ns, the cani ne and p remolar tee th a re not exposed w hen the supernumt:'rary teeth art' removed in the firs t

THE O RTHO DO NTIC TREATMENT O F IMPACTED TEETH

surgical p hase of the trea tment. Both in thi s tex t an d elsewhere (Becker et al , 1983; Koha vi e t al, 1984), we have been at pa ins to point out our opposition to the acce pted an d es ta blish ed practice of wide su rgical exposure of uneru p ted teeth in nonnal caSE'S wi th iso la ted im pacted tee th (La p pin, 1951; Le wis , 1971; vo n dc r Hevd t, 1975). G iven the underdevelopment of the ma xilla in the an te ro-posterio r pla ne and of both jaws in the vertica l plan e in cleidocra nial d ys pla sia (Kalliala an d Tas kin en, 1962; Zegarellt et al, 1978; Shafer et al, 1983), a nd the fac t tha t " ve ry lar ge nu m ber of unerupt ed teet h are presen t within th e bone and la rgely eliminating the sponglos um, the w ide remova l of the cortical plate (Smylsk i et al. 1974; H all Clod H yland , 1978; Richardson and Swinson 1987; Bchlfclt. 1987) would appear to be wasteful an d compromising. In the Je ru sa lem approach, access to the teeth is gained by a m inima l opening in the cortica l pla te, im media tely overlying the teeth. The size o f the opening is deter mined by two factors: (a) exposing a surface la rge eno ugh to aeromodate a small eyelet attachment; (b) enlarging this to th e minimum size that will a llow the surgeon to ac hieve haemostas is for long enough to allow the bond ing p roced ure to ta ke place in a co nta mination-free micro-environ ment. The re is no reaso n to re mo ve fu rther bone an d certainly not to reduce the vertica l heigh t of the ad jace nt cortical p late. The co mplete su rg ical flap s arc sutured back to close off the surgical field fully, an d healing is by primary in tention, w hich w ould a ppea r to offer a healthier a nd more rapi d per iod of heali ng a nd to promote a speedi er a nd more generous response on the part of the alveol a r bone (Laskin, 1985), The final pe riod ontal s ta tus of the teeth will also be more norma l (Beck er ct al. 1983; Kohavi el al, 1984). Deeply d isplaced tee th may th us be d rawn ocdusally through the overlying bo ne . which offers no real resistance to the rnccharucallv ass isted eruptive force: New al veola r bone accompanies the erupting tee th as they progress towards the occlusal plane, in a

CLEIDOCRAN IAL DYSPLASIA

ma nn er s imil a r to tha t occu rtng w ith normal, u na ssisted eru pti on in the normal pa tien t (Becker ct al, 1983; Kohavi et ,11, 1984 ). This w ill en hance the vertical height of the alveola r procesSt.'S of the tw o ja ws, incid ent ally deepening the labial a nd lingual su lci an d im pro ving the overa ll facial p roportions. In the other two methods, the need to maintai n pa te ncy of the exposure a nd visu al contact w ith the un erupt ed tee t h d icta tes tha t the bo ne level m ust be pa red down to tha t of th e deepest tooth. This clearly includ es the reduction of both the lingual an d buccal co rtical plates to thi s level - an d this in a patient whose alveola r processes a re already of redu ced height, because of the sy nd rome.

Figu re 9.20 Pano ra mic radiog ra ph of a pa lil'nl 12 Yl',l"" after all appliances were removed. A newly developing su pc mume rary pre molar loot h is noted.

PATIENT VARIATION Similarities a re seen among all of the patients su ffering fro m cleid ocra nial dysplasia, but there is a varying degree of expression of the va rio us characteris tic fea tures of the d isease, tog e the r w ith m.l ny other s po rad ic p henomena tha t have been repor ted to occur w ith the cond ition. Eru pted pe rm an en t incisors a re sometimes seen, and these may elimina te the need for the 'incisor-eru p ting' initial heavy archw lre, in one or both a rches. Instead, the tr ea tment ma y begi n w ith the levelling phase w it h the modi fied Johnson twin-wire arch. Some patients make their appearance for the first time a t an ad va nced de ntal age, w hen root a pex closu re has occu rred in most of the e ru p ted an d un er u pted teeth. Obviously, there is no d evelopme nta l determina nt to di vid in g the trea tme nt in to the abovemention ed stages , althou gh it may still be advisa ble from a strictly mechan ical poin t of vie w. It is difficult to d esign a n a ppli a nce tha t m ay efficiently extrude teeth in several ar eas a t the same time. Never theless, the in clusion of the cani ne s w ith the an terior tee th may have some merit in these cases. At the completio n o f all the trea tment and the p lace me nt of re tainers, new radi ogra phs should be ta ken to check for the de velop ment of recurre nt su pe rn u me ra ry teeth, w hich sometimes occurs in the 14-16-year-old

pa tie nt (Fig. 9.20). At this po in t, a ny decision regard ing the extraction of such tee th is strictly a s ur gica l one (Bec ker c t al, 1982; Becker and Shteyer . 1987). Whe n suc h tee th a re identified a t this lat e s tage, their extraction is no lo nger an orthod ontic decision, since fu ll align me nt of the teeth has been achieved and su ita ble re te ntion will preve nt an y adverse effects. Such factors as loca tion and accessib ility. incip ien t resorption of ne ighbouring e rupted teeth , and cysts will all influ ence the su rgeon rcgerdtng the ne cessity and timing of their e xtra ct ion .

REFERENCES Becke r A (987) Periodonta l sp lin ting v·..ith multistrand wi re follo wing orthodontic realignme nt of mi gra ted tee th: re port of 38 cases. l il t / Adliit Ortllmi Ort/lg/1 Surg 2: 99-1 09. Becker A, Gou ltsc hin J (1984) The m u ltistra nd re taine r and sp lint . AmI Ort//(/{i 81: 470--l .

THE ORTHODONTIC TREATMENTOF IMPACTED TEETH

228

------------'-=-=----=----=--=-=----~=----::..:..="--=-'Becker A, Shochat 5 (1982) Submergence of a deciduous too th, its ram ifications on the dentiti on a nd treatment of the resulting m alocclusion. Alii 1DrO/tl1l 81: 240-4.

Becker A, Shtcycr A (1987) A surgical and orthodont ic approach 10 the dentition in cleidocra nial d ysostosis. Trails Eur Ort/rod Soc 63: 121 (abstl. Becker A, Zilberman Y (1978) The palatally im pacted canine: a new approach to its treatment. Alii / Ortlwd 74: 422-9. Becker A, Bimstein E. Sh tever A (1982) Interdiscip linary treatm ent o( multiple unerup ted su pern umerary teeth. Am I Onhod 81: 417-22. Becker A. Koh avi 0 , Zilbe rma n Y (983) Periodontal status following the alignment of palatally impacted canine tee th . Am J Orthod 8-l: 332-6. Becker A, Lustmann J, Sbte yer A (1997a) Cleid ocranial d ysplasia: part 1 - general prtnciples of the orthodontic an d surgica l treatment modality. Am I Orthod Dentoiac Orttiop 111: 28-33. Becker A. Shtcycr A. Bimst ein E, Lustmann J 0 997b) Clei docrania l dysplasia : part 2 - a treatment protoco l for the orthod ontic and surgical mod ality . Alii I Orthod Dentoioc Ort/wl' 111: 173-83. Bchlfclt K (1 987) C leido-crania l d ysp lasia: diagn osis and trea tmen t concept. Trone Eur Ort/wd Soc 63: 25 (abst). Ben Bassat Y, Brin I, Puks A, Zil bcrma n Y (1985) Effect o f trauma to the p rimar y incisors O il perm an ent suc cess ors in diffe re nt developmen tal s tages. Ped Dent 7: 37-4. Bixler 0 (1976) Hered itable d isorders affecting cementum and the period Oil tal structures. In: Oml Facial Genetics ted RE Stewart, GH Prescott), pp 2R2-4. Mosby, St Lou is. Brin L Bell Bassa t Y, Puks A, Zilberm an Y (1984) Trau ma to the pr imary incisor s an d its effect 0 11 the pe rma nen t incisors. Ped Dell t 6: 78-82. Cohe n MM Jr (1976) Dysmorphic synd romes wi th craniofacial manifestations. In: ami

Fat'ial Ceneucs (ed RE Stew ar t, GH Prescot t), pp 566--7. Mosby, St Lou is. Davies TM, Lewis 01 1, C illbe GV (1987) The surgical and orthod ontic ma nageme nt of unerupted tee th in cleidocran ial d ysostosis. Br I Ortho 14: 43-7. Elomaa E, Eloma a M (1967) O rthodontic treatment o f a case of cleid ocrania l d ysostosis. 5110111 Hammasiaak Toim 67; 139-51. Frame K, Evans RIW (1989) Progressive develop me nt of supernumerary. tee th in cleidocra nial d ysp lasia. Br I Grtnod 16: 103-6. Frommer HH, Lapeyrolerie FM (1%4) Two case reports of cleid ocranial d ysos tos is. Ncu: York J Dent 34: 103--7. Go rlin RJ, Cohen MM [r , Levin l..S (1990) Syndromes of fIJe ncad and neck, 3rd edn, pp 249-53. O xford University Press , New York. G ron A (1962) Pred iction of too th eme rgen ce. J Dent Res 41: 573-85. Hall RK, Hyland AL (1978) Combined sur gical and orthod ont ic ma nagemen t of the oral abnormalities in ch ildren with cleidocranial d ysplasia . l il t I Oral SlIrg 7: 267-73.

Hitchi n AD, Fairley JM ( 974) Dental manageme nt in cleido-cra nial dysostosis. Br I Oral 5urg 12: 46--55. Howe GL ( 971) M i,lOr Oral Surgery, 2nd edn. pp 135-7. Wright, Bristol. Johnson JE (934) A new orthodontic mechan ism : the twin wire alig nment applianc e. 111/ I OrOwd 20: 946-63. Kalltala E, Tnskincn pJ (1962) Cleid ocranial d ystosis: report of 6 typica l cases and 1 atypical casc.l Oral Sflrg 15; 8U8- 22.

Kelly E, Nakamoto RY (I 974) Cle idocranial d ysostos is - a prosthod ontic problem . I Pros DCIII 31: 518-26. Koh a vi D, Becker A, Zilbcrman Y (1984) Surgical exposure, or thodontic mo vement and final too th po sition as fac tors in periodonta l b reakdo wn o f treated palatally impacted canines . Am I Or tJwd 85: 72-7. Lappin MM 095]) Practical manageme nt of

CL EIDOC RANIAL DYSPLASIA

- - - - - - - -- - - - - - - - - - - - -the impacted maxillary canine. Am / Ortll(Jd 37: 769-78. Laskin D (1985) Oral and Maxiffofacial Surgery, Vol 2, pp 4+-7. Mosby, St Lou is.

Lew is PD (1971) Prcorthodontic surgery in the trea tmen t of imp acted canines. Am J Ort/lOti 60: 382- 97.

Seow WK, Hertzberg J (] 995) Den tal devel opment an d mola r root len gth in chi ld ren with cleidocra nial d ysplasia . Pediatr Dent 17: ] 01- 5. Stewart RE, Prescott GH (ed s) (1976) Oral Facial Genetics. Mosby, St Lo uis. Tachd jian MO (]990) Pediatric Orthopedics. 2nd edn, p p 840-4. Saun ders, Phil adelphia .

Miller R, Sakamoto E, Zcll A et al (1978) Cleido cranial d ysostosis. A multid iscip linary ap p roa ch to treatme nt. j A m Dent Assoc 96: 296-300.

Trimble LD, West RA, McNeill RW (1982) Clei docran ial d ysp lasia: comprehensive treatment of the d ent ofadal abnormalities. j Am Delli Assoc 105: 661-6.

Muller EE (1967) Transplantation of teeth in cleidocrani al d yso stosis. In: Oral SlIrgery: Transactions of tlie 2nd Congress of the Internat ional As sociation of Oral Surgeolls Ied E Hu sted , E Hjortmg-Hansen). pp 375-9. Munksgaar d , Co pe nhagen.

Vermette ME, Kokich VG, Kenned y DB (] 995) Un coveri ng labially impa cted teet h: apically repositioned flap and closed -erup tion techniq ues . Allgle O rthod 65: 23-32.

Oksala E, Fagerstrom G 0971> A two-st age sutotransplantat ton of 14 tee th in a pa tient with cleidocra nial d ysos tosis. S ltoll/ HammIIs/aak Toim 67: 333-8.

Probs tcr L, Bachmann R, Weber H (1991) C ustom-mad e resin-bond ed attachme nts su pporting a removable pa rti al dent ure u sing the sp ark erosion techn iqu e: a case repo rt. Qll iJltcsfotllce Jil t 22: 349- 5-1 . Richardson A, Swinson T (I 987) Combined orthodontic and su rgic al ap proach to cleid ocranial dysostos is. Tra ns Eur Orthod Sec 63: 23 (abs t) .

Ricketts RM (1981) Perspectives in the clinical app lication of cephalome tries. The first fifty years. A llgle O rtlwd 51: 1]5-50. Shafer WG, Hin c MK, Levy BM (1983) A Tt'xlwok of Oral Pllth% SY, 4th edn. pp 678- 80. Sau nd ers, Ph iladelphia. She pard ES (196 1) Tecunique and Treatment wit" ti lt, Twill-Wire A pl /lim lce. Mosby, St Louis. Smylski PT, Woodside DC, H arn ett BE (1974) Su rg ical and orthod ontic treatment of cleid ocranial dysos tosis. Jil t j Oral 5/1rg 3: 380-5.

vo n d er Heyd t K (]9 75) The su rgical uncovering and orth odontic position ing of uneru pted maxillary canines . Am / Orthod 68: 256--76. Weintraub GS, Yestlovc IL (] 978) Pros thodontic therapy for cleidocranial dysost osis. Report of a case. ] Am DCllt Assoc 96: 30]- 5. Winther JE, Khan MW (1972) Cleidocra nial d ysostosis: report of 4 cases . Dent Pract 22: 215-]9. Yamamoto H, Sakae T, Da vies JE (] 989) Cleidocra nial dysplasia : a ligh t microscope, electron microscope an d cry stallographic study. O ral Su rg Orat Mcd Oral Path 68: ]95-200. Zachri sson au (1977) Clinical experience with di rect-bond ed orthod ontic retainers. A m j OrtJl/lit 71: 440-S. Zegar ellt EV, Ku tscher AH, Hyman GA (1978) DiaSllosis of Dieeaece of the Mouth lind j Il W S, p 137. Lea & Pebig er, Philad elphia. Zilberm an Y, Fuks A, Ben Basse t Y et al (1986) Effect of trauma to pr imary incisors on root developm en t of their pe rma nent successors. Ped Dellt 8: 289-93.

229

Index

Page num Oer'l in itaIIic refer t o the illustr.l tions

active ~l;aul arches 121-2. / 21 active remova ble pbites 18 1- 2. /88 Ada m's clup 166. 18 1

ad...1tpatienu d~is 178-80 m:;m qement 180-1 tempora ry pros the ses 18 1- 7 alignment group I anines I 17. 1/7

grou p 2 unines 120-3. 120 group 3 can ines 131-4 grou p " canines 134 grou p 5 anines 135-9 spootaneous 62 ancho r tee th 187 ancho rage implanu 196 uniu -«. 109. 120. 167 Angle's Clan II malocclUSion 10 ankylosis 29. 35. 'IS. 8 1 crown resorptio n 17 1-2 apical roo t dilaceratio n 73 app eara nce

11)- 11. 62-3 . 202. 211

appl iance s 109 see also mechanotherapy

active re movable plate 181-2 Adam's clasp 166. lS I

adult patients 193, 194 auxiliary labial w ire 122- 3. / 24 auxiliary springs 37 . 38, 46-9 ballist3 37, 12 1, 112 Begg brac kets 65. 222 bo x elast ics 72. 21 5-16

bracke ts 46-7, 46 buttons 77. 81, 170 early mixed de ntition 63-4 ectopic first mo lars 166 Edgewise bracket! .016, 65. / 59 er uptio n 113 extra -ora l headgear 157, 169 'finger sprinc /64 fixed versus remo vable 166

n . 179. 181. 187 Johnson 's (mod ified) twin-wire arch maxillary central incisors &4--8. 67-70 root dilace ration 7.01. 78 magnet! SO, 50 mandibtllar second molars 167. 168 multi-bncketed 44. 190 orthodontic bands .016 rem ovable 123 separato rs 166 Siam"'se bracketS 46. 167 threaded pins 45--6. 45 arch le ngths 111 archfo rm 110--11. 217 archwires ancho rage eases 44 buccal 68 elas uc di spla~ement 49 incisor-aligning M. 2 13. 2 16-- 17. 2/ 7 incisor-erupting 2I 3. 2/3, 2!.oI, 2/5 mandibular canines 15.01 palatally di sp la~ed ~an;nes 111- 12 toot h transpo sition 190 attachments .01 4-8 bonding 30, 31. 36-40. 38 butto ns 77.8 1 extra-o ral ancho rage 196 eyelets 37. 39, 47-8, 47 group I canines I 18- 19 gro up 2 canines 120 group 3 canines 130-1 Goshgarian bar 186- 7, /88- 9 auxiliary labial wires 122- 3. / 24 auxiliary spr ings 37. 38. 48- 9. 120--3. /2 4 flippe r (Spoo<1) de ntures

ballista 37, 12 1, / 21 bands, orth od ontic 46 Begg brackets 65. 222 Beggtech nique 111- 12 Il
;agents 39 atta chmenu 30. 31. 36--.0\{). 38 unfilled resin 196

boeo channelling 26 cleidocranial dysplasia 207 height 71 support I 13-1.01. 1/ 4 bolt e lastics n . 215-16 bnckeu . o rthodontiC 46-7, 46 bridge abutment 193. 196 buccal arche s 187 buccal impaction maxillary a nines 151-3. 152-3 surgical e "posure 30-2. 3/ . J2 buccal tra ction 128. /32-3 butt onho ling 32. J2 butto ns 8 I. 170

n.

canines CT scanning 22 deciduous cynic changn 97-98 , 97 e" tra ction 102. 103. 104 mor bidity 96 root non -re sorption 90, 9 / development 86-8, 87 ",ruptio n 6. 88 mandibular .ol, 154-6 . / H. 155, 156,

/88-9 maxillary 89 er uptio n 26 impa ~ti on . buccal 151- 3, 152- 3 inspectio n 100 missing 186-7 palatal /5 radiography 21 root developm ent 4 palatal classification 112-47 displace ment theo ries 88-9 6 impaction 86 co mplications 96- 100 diagnosis 100- 1 ""'tra ctio n I I I, 113

INDEX --.::.:::::

232 cont'd grou p I 115-19,116-1 7

group 1 gro up 3 group ~ groo p 5

119- 27. 1/ 9, 126-7 128-3'4. /29 134-5. /36-7 135-9. /38. 139

110-12, I

so.

1/ 1.// 2 prevalence 85-6 treatment. tim ing 10 1- 9 radiography / 9. 101 pre~tiYe

t rea tment,

102-5

cen tral incisors

congeniW . bsen<:e 53 di~5;S S~ 1

dilaceration 2 /.

ss-e. 72-6

erup tion 53 prognos is 71-6

root ~elopment 55. 56. 58. 72-6 lpOIce Ion 8. /6 ~.t tml!flt

61-82

centnlma ndlbular incisors 4-S childre n central inci$Ol"$ 53. 5 4. 62

detlD.l age I-t.. 2. " dq,gnosis 8

o rth odo ntic separ.llton 166 surgical interventio n 9 trau matic injury 55-9 , 68-70 c1eidOCl7onial dylpl.tsia 199-200.20 0.

20 / ,202 Belfast -Hamburg appro4lch 205- 7 diagnosis 2 11 Jenosalem approach 207-9. 211-22. 226 lo ng-t e rm retentiOl'l 2 10 pat ient variat ion 227 pnil'l'1t

"

mars upializatio n 174

grou p 6 139-4 6 heredity 95- 6 mectu.oothelOlp~

paiatally impact ed canines 98, 98 CT see com put ed toroograp hy cYSts de ntigerous 8. 98, 174, 176 palata lly imp;act ed can ines 97. 97,

well·being 209. 210

To ront o-Melbo urne appro ach 204-5

treatment 202-4, 222, 225. 226-7 computed to mography (e T) scann ing 22, 23. 2001 palatally impacted can ines 99 cross- bite 182 cro w ding 7. 8. J2 c1eidocraniai dysplasia 209- 10 extraction 111 - 12 mandibular canines 156 mandibular second premolars 157 maxiilary f,rst mo lars 165 palatally impacted canine s 89-90. 89.

102 crowns amputati on 76 calcificat ion 4 dilaceration 56. 73-4. 75 resorption 33 see also r eplaceme nt res~ption ankylosis 17 1-2 impaction 169-70

deciduous teeth cyst ic cha nges 97-98. 9 7 extraction 102. 103, 104 reClined 3, 3. 5, 8. /0 cleidocranial dysp lasia 202, 107 mandibular second prem olars 157-8 su pernumerary teeth /6 surgical intervention 17-tl de na l age 1--0. 102. 2 11 denta l foiliciM cystic change 97. 98. 99 surgical exposure of imp;act ed teeth 9. 33-5.34 de l'lQl history 59 dentigerous cysts 8, 174. 176 p;alatally impacted canines 97. 9 7. 99 d~eloprnent

can ines 86-8. 87 denCll age 1--0. 33 denal fo llicles 33 dilaceration 55-7 dilacera tion apical root 13 central incison 2/. 55-8. 60--1, 66,

,2-<>

Edgewise brackets 46. 65. /59 elas tic ligat ure s 47- 9. 48, 49, 72 elastic traction 193-96 enucleation 174 eruption can ines 6, 26. 88 delayed 3, 6-7, 53, 61 for ced 113- 14 full flap closur e 31-2 maxillary central inciso rs 6, 53 prem ature 6. 9 pr imary failur e of 17 1 sponta neous 62 surgical int erven tion 26-8 , 27 t ract io n 109 et ching 38. 130. 196 exp osure 27--8, 2 7,28, 38, 109 extra-o ral anchorage 196 extra -oral headgear 157. 169 extra-o ral rad iograp hy 17 extra ctio n cro wding 111-1 2 de
mandib ular seco nd pr eroolars 157 palatally impacted canines I I I. 113 preventive trea tment 102-5, 103, 104, 105 eyelets 47-8. 47 atta chment 37, 39 Srou p I canines 118-1 9 s roup 2 can ines 120 s roup 3 can ines 13e-1 facial appea ranc e 10--1 1. 62- 3. 202.

211 'finger' spring /64 flippe r (spoon) dentures n.

I~.

18 1.

18'

follicular sacs 97. 98. 99 free -end edentulous saddles 193 gold cllain ligatu r es 47 Goshgarian bar 186-7, 188-9 ",idance theory 90-3

hard tissue obstnlctions 28-9 headg ear 157, 169 healing, by sKondary int en tion 9 he redity cleidocranial d'y$plasia 199 gu idance theory 9s-6. 95 infnocclusion r7 1. / 73 Hertwigs root sheath 57. 58. 58 Impaction buccal 15 1- 3. 152- 3 surgica l e xpos ure 30-2. 3 1. 32 co mplicatio ns 58 crown re sorption 169-70 diagnosis 6-11, 9 disguise 178-80 guidance t heory 90-3 hard tissue ob stnJctiOf1 28-9 negle<:t and disS"ise 178- 80 obstructed 71-2 odor aome s 86 palatal complitations 96- 100 diagnosis 100- 1 grou p I can ines 11 5- 19, 1/ 6-17 grou p 2 can ine~ 1 19~27, 1/9 . / 26- 7 group 3 can ines 128- 34, 129 group 4 ceooe s 134-5, 136- 7 group 5 canines 1 3 5~9, /38. /3 9 group 6 canees 139--46 heredity 95-6 me chanoth er apy 110- 12, , 10. III,

112 prevalence 85-6 t reatme nt t iming 10 1- 9 r.ld'osraphy 13- 24 surgical ex posure 8- 10. 25-'11 tra umat ic causes n-82 implants 180. 196

INDEX incisor-aligning arc hwir('$ 6-4, 2 1), 2 16- 17. 2 / 7 incisor~rupting arch wire$ 2 13. 2/3. 2 14.

115 incisors centnl dilacented 2 1 rTWCi llary arrested root develo pment 58 co neenita l absenc e 53 diagnosis 59-61 eruption 53 obs tru aive causes 53--5, 7 1-2 pr ognos is 7 1-6 space los s 8. 16 tra umanc caus es 55--9. 72-5 t reatmeM 6 1-82 m in ing 182- 5 root de velo pment 4-S eruption 6, 53 latera l extraction 1 03~5. 106 maxillary 4-5 , 10 palatally impaned canines 9 1-3. 92. 94.99, 110, 110 root developmen t 4-5. / 0 root re rorption 141. 142-3. 144-5. /46. /47-8 late 98- 100. 99 maxillary 87 . 14 7-8. 19/-J inlTaocciusion deciduous teedlI 59-6 1.1 62. /63. 164-5 extn<:Von 161 non- ankylotic In. 174 perma nent tee th 17H , /71, 172 surgia l e ltposu re 29 intru sive luu tion 58-9. 76-82, 77--lJO

jer usaleen approach diagnosis 2 1 I ormodontic~

2 /2-/3. 2 13-1 8. 2 14. • 22G-2, 223--4 surgery 2 14, 219 [c hr ac n's (mo dified) tw in-wire arch cleidoc ra nial dysplasla 213 maxillary cent ral inciso rs 64-5, 64.

66, 67-8,6 7, 68-70 ro ot dilacer ation 74. 78 lasso wires 45. 45 lat eral i nci ~Ol's exrra ction 103--5, 106 palatally impacted caoees 9 1- 3. 92, 94,99.1 10. I / O root deve lopme nt 4-5. /0 root r esorption 98- 100. 99. 111. / 41-8 lateral mandibular incisol"$, root de~lopment 1. 5 b ter.lllopen bite 16 1. / 63 lesions, so ft tissue 28

ligatu res elu Dc18-9, 48. 49, gold chain 17

n

p~1 17-8 . 214- 15

sllnp hot ebstic 49. 1/ 6. 118 stainless n eel17--lJ

magnets 50, 50 malocclusion 10. -41 mandibles arc h. r.lIdiogr.llphy 11. / 4 a nines 1. 154-6, 154-6, /88-9 rem ovable appliance 123 ~econd molars 167. 169 ~ecood premolan 157, 157-9, 158,

160 marsupialization 174

maxilla ante rior occlusa l 14. /5 arch radiograp hy 14. /5 canin es 89 er upt ion 26 impact ion, buccal 151-3, 151- 3 inspection 100 missing 186-7 palata l /5 r;adiogr;aphy 2 1 root developm ent 4 centr.l l incisors arrested root de~lopment sa coo gen ital abse nce 53 diaenos is 59-6 1 prognosis 11-6 space Ios ~ 8. / 6 treatment 6 1-82 first mo lars 165--7. 175-6 first prem olars, root development 4 inciSOI"$ 8 7. /47--8 latenl inciso rs. root development

+-5. /0 second premolars 16 1. 161. 163,

164-5 me chanotherapy see also appliance s cleidocranial dyspla$ia 208-9 eruptio ns 62 gr oup 5 canines 138- 9, /38 palatally impacted canines 109- 12 timing 105, 108-9 me dical hiSto ry 59 mesial cro wn displacement 118--19 molar bands 187. 188. 190 molars elastic traction 193-6 eruption 6 mandibular sec ond 167.1 69 root development 4--5 second deciduo us 159--61 th ird 193. 196 mosquIto forc eps 39

odontome~ 7. 5.04, 60 O nts pro jection /5 onl hygiene n. 108. I 12. 125, 176, 211 orthophosphoric acid 36 ovNjets 182

palatal ippro
234

- - - - - - - - -confd cephalometric 20. 20. 2 / , 22 cleidocranial dysplasia 200. 201 crown re so rp tion 169

de
nuxillary can ines 2 1 maxillary firs t molars 165 maxillary second prem obn 16 1

occlusal 14-1 6. / 4. /5 odon tomes 60 p.lrall:u method 17- 2l 1B

penapia.1 8. 1l -1 4,/6 roo t resorption 140

20. 21,22 ~pbcement re5o.-ption 8 1. 98. 169 views at right-aneles 1&-22. / 9.

see also anlo:yIosis ~iOIi>tJon

see also ankylosIS crown 33. 98. 98. 169- 72 incisort 98-100. 99. '4 1, / 42-8 replacement 81. 98. 169

rcc r :axial ori entation 220. 222 development 4-5. /0 OlITflt ed 58 canioes ..

separato rs, orthodontic 166 Siamese brac kets 46, 167 slingshot elastic 49, 1/ 6, 118 soft tissue 28, 55 , 72 soldered palau l arc hes 182, / 83. 184--6 spac e closure 153 space opening 105, /07, 110, /1 0 spongiosum 207 su inless steel ligamres 47-8 supe rnumerary teem 7, 5 3~5. 202. 207 supp lemen tal t eem 199 surgery atD.chm en t bo nding 36----40 cletdoc......ial dysplasia 20 3-9 de ntigerous <:y5ts 174, 176 6'Upti on s 26-8 , 27 exposure 27-8. 27.28.38 group I canines 117 groop 2 c,mi nes 119- 20 gro up 3 canines 128-34 group 4 can ines I H group 5 can ines 135 impaa ed teem 8-10, 25. 31)..-5, 4 1 mandibular canines 15-4 mandibular second ....emolars 157 wft tissue lesions 28 timing 9--10, 207-8 surgical flaps ~cal repositio ning 30. 31. 109. 128 closu re 3 1-3. 35, 47

dental ace 2. 3-5, J impacted centrlll incisors 55. 56.

58.72-6 dilaceration 73 displacem ent 119. 125 Hertwig s Illeam 57. 58. 58 non -resorp tion 90. 9 1,1 14- 15

orie ntation. cor re ctio n 75

resc rpucn central inciso rs 98- 100. 99.

/4 2-3. /4 4-5. 146

''' 1.

lat er al incisors 14 1, 147-8 p~lnOi lly impOicted canines 140 rotati on 118, 120, I2S secondary int ent io n, healing 9

m ird molars 193, 196 m readed pins 45-6, 45 Tip-Edge technique 11 1-1 2 teeth buds 54--6 toot h de velopm em canine s 86-8, 8 7 de ntal age 1--6, 33 den ta l follicle 33 dilacer ation 55-7 tooth germ displacement 95. 96, 96, 97 tooth position, parallax method 17- 22, ! 7, 18 Toromo -Melbourne approach 204--5 t raction

B1 BU OT I"' ~ I"'\ I .l e:: n~ L' tnll""O~S'TE::

r--t ...:

:;1 "': '!

U ,r' ,8 . 0 ' T--:~ l r""'L'J G I ~ 1 , ru )

: ,- ~ ,, : 1 .

92 12 0

:VIONTRO U G E

-. ..r.~" '(

INDEX

- - - - - - ----"= attachment bond ing 40 buccal. grou p 3 can ines 128, 132-3 de ntal follicle 33-5 direc t vers us two-stage /3/ elastiC 193--6 mechanotherapy 109 orthodontic 33- 5.40 tra ns-palata l bars 186-7, /88-9 tra nsplantation 203 tra nsposition 138-9./38. 156, 190 tra uma u.nines 72-72 centra l incisors 55-9 children 55-9, 68-70 intrusive luxation 58-9, 76-82. 77-410 soft tinue 55 tr en ml!flt see aiSlI appliances An&fe's Class II malocclusion ot elastic 49, /16, 118 sta inles s Steel 47-8 magnets 50, 50 pre ventiv e 102- 5 m r eaded pins 45--6. H timing 6 1. 10 1- 9 tr ue (vert e"') occ lusal I S, / 5 runnel approach 128, 130 well. being. psycho logical 209, 210 Whitehe ad's varnish 9, 25, 159