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 1.8y of L Shapira.)

27

SURG ICAL EXPOSURE OF IMPACTED TEETH

Figu re 3.3 Following exposure and packing, tlw tooth has erupted spon tand 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 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 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

'

\

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.)

,
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) (.)

(

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

Cdl

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

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THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

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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 O.'CII from th.. right side. (k,D U~ uf palatal 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 ;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