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[A. becker, adrian_becker]_orthodontic_treatment_o(book_fi.org)

  1. 1. The Orthodontic Treatment of Impacted Teeth ADRIAN BECKER BOS, LOS RCS, 000 Re ps Clinical Associate Professor, Department of O rthodontics, Hebrew University- Hadassah School of Dental Medicine, founded by the Alpha Omega Fratern ity, Jerusalem, Israel MARTIN DUNITZ
  2. 2. CIM..rtin Dumtz Ltd I99S Fi~t published in the Unikd Kingdom in 1998 by ~1..rtin Dunitz Ltd Tbcl.ivcrv House 7-9 Pratt Street t..ondufl NW I OAE All rights reserved. No pari of this publication milY b..• reproduced , ~tnrt-'d in .1 retrieval system, or transmitted, in any form or by any means , elect ronic, nwch.m ic.ll, photocopying, roc...rd ing or othe rwise without the prior permission of the publisher or in acco rdance with ttlt' provisions of th.., Co pyright Acl 19118, or under the• terms of any licence pcrmitti n~ limited copymg issued by th.., Copyright Licensing Agen '-1', 33-34 Alfred PIaU', London WCIEroP. , CIP catalogue record for th i~ btxlk is a'ailable from the British Library ISBN 1115317 32f! 2 Composition t>y w earsct, Boldon, Tyne and Wear Printed and bound in Singapore
  3. 3. CONTENTS Preface vii 1. General principles related to the diagnosis and treatment of impacted teeth __ 1 2. Rad iographic methods related to the diagnosis of impacted teeth 13 3. Surgical exposure of impacted teeth 25 4. Treatment strategy 43 5. Maxillary central incisors , 53 6. Palatally impacted canines 85 7. Other single teeth 151 8. Impacted teeth in the adu lt 179 9. Cleidocranial dysplasia 199 Index 231
  4. 4. PREFACE There can be little question that the treatment of impacted teeth has caught the imagination of many in the den tal profession. The cha l- lenge has, over the years, been taken up by the general practitioner and by a number of dental specialis ts, including the paedodonttst, the period on tist, the orthodontist and, most of all, the oral and max illofacial surgeon. Each of these professionals has much "input" 10 offer in the resolution of the immediate problem and each is able to show some fine results. However, no sing le individual on this specialist list can completely and successfully treat more than a few of these cases, without the assistance of one or more of others of his/her colleagues on that list. Thus, the type of treatment prescribed may depend upon which of these denta l specialists sees the patient first and the level of his/her experi- ence with the problem in his / her field. Such treatment may involve su rgical exposure and packing, it may involve orthodontic space opening, perhaps auto-transplantation, or a surgical dentoalveolar set-down procedure, or even just an abnorma lly angulated pros- thetic crown reconstruction. Experience has com e to show tha t the orthodontic/surgical moda lity has the poten- tial to achieve the most satisfactory resu lts, in the long term. Despite this, many orthodon- tists have ignored or abrogated their respon- sibility tow ard s the subject of im pacted teeth to others, accounting for the popularity of other mod alities of treatment. The subject has become something of a Cinderella of den- tistry. Vith in the orthodontic/surgical modality, much room exists for deba te as to what should be done first and to wh at lengths each of the two specialties represented should go in the zea lous pursuit of its allotted portion of the procedure. The literature offers scant information and guidan ce to resolve these issues, leaving the practitioner to fend for him / herself, wi th a problem that has ram ifi- cations in several different specialist realms . This book discusses the many aspects of impacted teeth, including their prevalence, aetiology, diagnosis, treatment timing, treat- ment and progn osis. Since these aspects differ between incisors and can ines, and between these and the other teeth, a separate chapter is devoted to each. The ma terial presented is based on the find ings of clinical research that has been carried out in Jerusalem by a small group of clinicians, over the past 15 years or so, at the Hebrew University - Hadassah School of Dental Medicine, fou nded by the Alpha Omega Frate rnity and from the glean- ings of clinical experience in the treatment of many hundred s of my patients, yo ung and old.
  5. 5. viII An overall an d recommended approach to the treatment of impacted teeth is presented and emphasis is placed on the periodontal prognosis of the results. Among the many ot her aspects of this book, the intention has been to propose ideas and principles that may be used to resolve even the most difficult impactions, employing orthodontic au xil- iaries of many different types and designs. None of these is specific to any particular orthodo ntic appliance system or treatment "philosophy", notwithstand ing the autho r's own personal preferences, which will become obvious from man y of the illustrations. These auxiliaries may be·used w ith equal facility in virtually any appliance system with ,vhich the reader may be fluent. The only limitations in the use of these ideas and principles are those imposed on the reader by his/her own imagination and willi ng ness to adapt. The orthodontic man ufacturers' catalogues are replete wit h the more commonly and rou- tinely used attachmen ts, archwircs and auxil- iarics, which Me offered to the profession with the aim (If streamlining the busy prac- tice. These catalog ue items have not been tai- lored to the demands of the clinica l issues that are raised in this book. Thes e issues, by their very natu re, are exceptional, problem- atic and often unique, while occurring along- side and in addition to the routine . Among the more common limitations self-imposed by many orthodontists has been the disturbing trend to rely so completely upon the use of prefo rmed an d pre-welded attachments that they have forgotten the arts of weld ing and soldering and no longer carry the necessary modes t equipment. This then res tricts one's practice to using only wh at is available and sufficiently commonly used to make it com- mercially worth while for the manufacturer to produce. By conse nting to this unhealthy situ- at ion, the orthodontist is agreei ng to work w ith "one hand tied behind his/ her back" and treatment results will inevitably suffer. I acknowledge and am grateful for the help given me by several colleagues; in the prepa- ration of thi s manuscript. An excellent profes- sional relationship has been established and has withstood the tes t of time, w ith two senior members of the Department of Oral ORTHODONTIC TREATMENT and Max illofacial Surgery at Hadassah, with whom a modus operandi has been devel- oped, in the treatment of our patients. Professor Arye Shteye r. Head of the Department and, su bsequently, Professor Josh ua Lustmann have educated me in the finer points of surgical procedure and care while, at the same time, ha ve demonstrated a respect and understanding of the needs of the or thodontist at the time of su rgery. I am grateful to them for their collaboration in the wri ting of Chapter 3. Dr llana Brin read the original manuscript and made some useful suggestions, which have been included in the text. I am grateful to Dr Alexander Vardimon for his comments regarding the use of magnets and to Dr Tom Weinberger for the discussions that we have had regarding several issues raised in the book. My wife, Sheila, read the earlier manu- scrip ts an d made ma ny important recommen- dations and corrections. More than anyone else. she encouraged me to keep writing dur- ing the many months when other and more pressing responsibilities cou ld have been used as justifiable excuses for putting the pro- ject aside. My colleagues, Dr Monica Barzel. Dr Yccheved ben Basset, Dr Gabi Engel, Dr Doron Hare ry. Dr Tom Weinbe rger, Professor Yerucham Zilbcrman, and my former gradu- ate students Dr Yossi Abed, Dr Dror Eiscnbud. Dr Sylvia Geron, Dr Immanu el Gillis, Dr Raffi Romano and Dr Nir Shpack, have provided me with several of the illustra- tions included here and I am indebted to them. [ am grateful, too, to Ms Alison Cam pbell, Commissioning Editor at Martin Dunitz Publishers and to Dr Joanna Batragel, Technical Editor, for their con structive and professional critique of the manuscript, which contributed so mu ch to its ultimate format. I also thank Naomi and Dudley Rogg, of the British Hernia Centre, for the computer and office facilities that they placed at my disposal during my short sabbatical in London, in the latter stages of the preparation of the work for publicat ion. Perm ission to use illustrations from my own ar ticles that were published in va rious
  6. 6. PREFACE learned journals was granted by the publish- ers of those journals or by the owners of the copyright, as follows> Figure 5.13 was reprinted from Peretz B, Becker A, Chosak A (1982). The repositioning of a traumatically-intruded mature rooted permanent incisor with a removable appli- ance. [Pcaodont, 6:343-354, with kind permls- sion of the Journal of Pedodontics Inc. Figu res 5,4 & 5.12 were reprinted from Becker A, Stern N, Zelcer Z (Copy right 1976) Utilization of a dilacerated incisor tooth as its own space maintainer. f. Dmt. 4:263·264, with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington OX5 1GB, UK. Figures 9.8-9.14 were reprinted from Becker, A., Shteyer. A, Bimstcin, E. and Lustmnnn, J. (1997), Cleidocranial dys plasia: part 2 - a Treatment Protocol for the Orthodontic and Surgical Modality. A m. I. Orthod. Dentojac. Orttiop. 111:173-183, with kind permission of Mosby-Year Book Inc., SI. Louis, MO, USA. Figure 6.35 was reprinted from Kornh auser, S., Abed, Y., Harary, D. and Becker, A. (1996), The resolu tion of palata lly- impacted can ines using palatal-occlusal force from a buccal auxiliary. Am. /. Orthod. Dentofac. OrthoJ'. 110:528-534, with kind per· mission of Mosby-Year Book lnc.. St. Louis, MO, USA. I am very thankful for their cooperation and for their agreement. Ad rian Becker [crueolein
  7. 7. 1 GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH CONTENTS • Dental age • Assessing dental age • When is a tooth co nsi dered to be Impacted? • Imp act ed teeth and local space loss • Whose problem? • The timing of the surgical intervent ion • Patient motivation and the orthodontic option In order to understand what an impacted tooth is and whether and when it sho uld be treated , it is necessary to first define our per- ception of normal development of the denti- tion as a whole and the time frame within which it operates. DENTAL AGE A patient's growth and develop ment may be faster or slower than average, and we may assess his or her age in line with this develop- ment (Krogman, 1968). Thus a child may be relatively tall, so that his morphological age milY be considered to be advanced. By study- ing rad iographs of the progress of ossification of the epiphyseal cartilages of the bones in the hands of a young patient (carpal index) and comparing this with average da ta values 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 sec- ond ary sexual features, a mental age assess- ment (lQ tests), an assessment for behaviou r and another to measure a child's self-conce pt. These indices are used to complement the chronologie age, wh ich is calculated d irectly from the birth date, to give further info rma- tion regarding a particular child's growth and development. Dental age is another of these pa rameters, and is a particularly relevant and importan t assessment, wh ich is used in advising proper orthodontic treatment timing. Schour and Massier (1941), No lla (1960), Moorrces et al (1962, 1963) and Koyourndjisky-Kaye et al (1977) have d rawn up tables and d iagram- matic charts of stages of development of the teeth, from initiation of the calcification process throu gh to the completion of the roo t ap ex of each of the teeth, together with the average chronologie ages at wh ich each stage occur s. Eruption of each of the va riou s groups of teeth is expected at a particular time but this may be influenced by local factors, wh ich may cause pn'mature or delayed eruption, with a wide time-span d iscrepancy. For this reason, eruption time is an unreliable method of assessing dental age. With few exceptions, mainly related to frank pathology, root development proceeds in a fairly constant manner - usually regard- less of tooth eruption or the fate of the
  8. 8. 2 deciduous predecessor. It therefore follows that the usc of tooth develop ment as the basis for dental egc assessment, as determined by exa mination of pe riapical or panoram ic Xcravs, is a far more accurate tool. Thus we may find that a child 11-12 years old has four erupted first permanent molars and all the pe rmanent incisors only, wit h deci duous can ines and mo lars com pleting the erupted den tition. Were the practitioner merely to run to the eruption chart, he wo uld noll' that at this age all the permanent canines and premolars should have erupted and he would conclude that the 12 deciduous teeth are over-retained and should be extracted! However. two possibilities exist in this situ- ation, and the radiographs must be studied carefully to distinguish them from each other. In the event that the radiographs show the unerupted permanent canines and premolars THEORTHODONTIC TREATMENT OF IMPACTED TEETH ha ving completed most of their expected rout length, then the child's dent al and chrono- logic ages coincide (Fig. 1.1). The deciduous teeth have not shed na turally, because of insufficient resorption of their roo ts. As such, we have to presume tha t they provide the impedimen t to the no rmal eruption of the permanent teeth. The ir permanen t successors may then strictly be defined as having de- lap..-d eruption. Under these circumstances, it would be a logical decision to extract the deciduous teeth, on the grounds that their continued presence defines them as over- retained. The second possibility is that the radio- graphs reveal relatively little root develop- ment, corresponding more closely perhaps to the picture of the 9-year-old child on the tooth development chart (Fig. 1.2). The child's birth certificate may indicate that he is 12 years of Figure 1.1 Advanced root development of the canines and premO" lars, definin g thl'b.' teeth ,IS exhibiting delayed eruption. Extraction uf the deciduous t"o.'Ih is indicated. Figure 1.2 An tt -yea r-old patient wi th roo t development defining de nial age as 9 years. Extra ction is con traind icated .
  9. 9. GENERAL PRINCIPLES RELATEDTOTHE DIAGNOSISAND TREATMENT OFIMPACTED TEETH 3 age an d this may well be supported by his body size and development an d by his intelli- gence. Nevertheless, his de ntition is that of a child 3 years younger, defining his dental age at 9 years. Extraction in these circumstances would be the wrong line of treat ment, since it is to be expected tha t these teeth will shed normally at the appropriate delltal age, and early extraction may lead to the undesired sequelae that are characteristic of early extrac- tion. performed for any other reason. From this d iscussion, we are now in a posi- tion to define the terms that we shall use throu ghout this text. The first refers to a retained deciduous tootu. which has a positive connotation and which may be defined as a tooth tha t rem ains in place beyon d its normal shedd ing time. owing to absence or retarded development of the permanent successor. By contrast, an d with a negative conno tation, an coer-retained deciduous tooth is one whose unerupted permanent successor exhibits a root development in excess of three-quarters of its expected final length (Fig. 1.3). A permanent toottt unth lidaycd emptio" is an unerupted toot h whose roo t is developed in excess of this length and whose spontaneous eruption may, in time. be expected. A too th tha t is not expec ted to eru pt in a reasonable time in these circumstances is termed an impacted tooth, Den tal age is not assessed vith reference to a single tooth on ly, since some vari ation is found within the differen t groups of teeth. An all-round assessment must be made, and onlv then Gill 01 definitive de termination be off~red. However, in doing this, one should be wary of including the maxillary lateral incisors, the mandibular second premolars and the third molars, whose de velopm ent is not always in line wit h that of the remaining teeth (Garn et al, 1% 3; Sofaer, 1970). ASSESSING DENTAL AGE When studying full-mouth pe riapical radio- graphs or a panoram ic film, there are seve ral criteria that may be used in the estimation of tooth development. The first radiographic Figu re 1.3 The mandibular left second deciduous molar is retained (extraction coneremdjcated), since the root dt>,velopment of its successor is inadeq uate for normal eruption. The right maxillary deciduous canine. in oonlrast, is over- ret ained (extraction advised), SIfCl' its long-rooted SUCCl.-~ sor has delayed eruption. signs of the presence of a tooth are seen shortly after initiation of calcification of the cusp tips . Thereafter, one may atte mpt to delineate the completed crown form ation, various degrees of fool formation (usually expressed in fractions), through to the fully closed roo t apex. By and large, orthodontic- treatment is performed 0 11 a relatively older section of the child population, and, as such, the stages of root (ormation are usually the onlv factors that remain relevant. The stage of too th development that is easi- est to de fine is tha t relating to the closure of the roo t apex. For as long as the denta l papilla is discernible at the roo t end , the apex is open and still developing. Once fully closed, the papilla disappears and a continuous lamina dura is seen to intimately follow the root out- line. The accu racy with which one milY assess fractions of an unm easurable and merely 'expected ' final root length is far less reliable and much more subject to ind ividual observer variation. Root development of the permanent teeth is completed approximately 25 - 3 years after normal eruption (Nella. 1960). This allows us to conclude that, at the age of 9 yea rs, the
  10. 10. 4 mandi bular incisors (which erupt at age 6) will be the first teeth to exhibit closed apices and that these will usually be closely followed by the four first permanent molars. At 9.5 years, the mandibular lateral incisors will complete, while at 10 and 11 years respectively, the max- illary central and normally developing lateral incisors will be fully formed. Th is being so, when presented with a set of radi ographs, we may proceed to assess denial age by following a simple line of investiga- tion, which uses the dental age of 9 years as its starting point and then prog resses for- wards or re-traces its steps bac kwards, depending upon its find ings. If the mandibular cen tral incisor roots are complete, we may presume the patient is at least 9 years old (de ntal age), and we may then advance, chec king for closed apices of first molars (9-9.5 years), mandi bul ar lateral incisors (9.5 years), max illary central incisors (to years), normally developing maxillary lat- eral incisors (11 years), mandibular canines and first premolars (12-13 years), maxillary first premolars (13-14 yea rs), normally devel- oping second premolars and max illary canines (14-15 years), and second molars (15 years). Figu re 1.-1 Root apices are closed in all fir«t molars, all mandibular and three maxillary incisors, ("'eluding the monilial)' left lateral inciso r. THE ORTHODONTIC TREATMENT OF IMPACTED TEETH By this method, we may arr ive at a tenta- tive diagnosis for dental age, on the basis of the last tooth in this sequence that has a closed apex (Fig. 1.4). It is no v.., important to relate the actual development of the remain- ing teeth in the sequence to their expected development that may be derived from the wall chart or from tables that have been pre- sented in the literature. This may then pro- vide corroborative evidence in support of the dental age determination. When the dental age is less than 9 years, none of the permanent teeth w ill have com- pleted their root development, and the clin i- cian will have no choice but to rely on an es timation of degree of root development, degree of crown completion and, in the w ry young, init iation of crown calcification (Fig. 1.5). This is most conveniently done by work- ing backwards from the expected develop- ment at age 9 years and comparing the dental develop ment status of the patient with this, beginning with the mandibular central inciso rs and the first permanent molars. Thus, at dental age 6 years, one would find one-half to two-thirds root length of these teeth. and this could be corroborated by studying the development of the other tee th. At the same Figure 1.5 Xo closed apices. Dental age assessment 7.5 }'N T'5.
  11. 11. GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH 5 time, one sho uld expec t unerupted maxillary central incisors wit h one-half root length, mandi bular canines with one-third roo t length, first premolars with one-qu arter root length, and so on. As pointed out earlier, variation occurs, and this may lead to certain apparent contra- dictions. In such cases, elimina ting the maxil- lerv lateral incisors, the mandibular second premolars and the third molars will usually simplify the procedure an d contribute to its accuracy, since these teeth are more indivi- dually va riable compa red with the rest of the dentition. Addition ally, un usually small teeth, cun iform premolars and mandibular incisors, and peg-shaped lateral incisors are most often to be seen developing very much later (sometimes as much as 3 or 4, years later), and should not bt> inclu ded in the over- all estimation. One may then present a deter- mination for the den tition as a whole, with the added notation tha t an individual tooth may have a mu ch lower den tal age. We may occasionally examine a I-t-year-old patient who has a complete permanent den ti- tion. including the secon d molars, with the exception that a mand ibular second decidu- ous molar is present. The radiographs (Fig. 1.6) show the apices of the first molars, cen- tral and lateral incisors, ma nd ibular canines and premolars to be closed, while the maxil- lary canines and the second mo lars are almost closed. However, the unerupted mandibular Figure 1.6 A late-developing left mandibular second premolar. (Courtesy of Dr MBaezel.) seco nd premolar has an o~1l'n root apex and development equivalent to abou t half its eventual length. On the basis of the informa- tion gathered , we may assess the dental age of the den tition as a whole to be 14 years. At the same time, we should have to note tha t the dental age of the unerupted second pre- molar wa s approximately 10 years. Having made this determination, we may now con- fidently say that the second premolar, in- divid ua lly, does no t exhibit delayed eruption and the deciduous secon d molar is not over- retained, in the terminology used here. Accord ingly, it would 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 nor- mally. To summarize this discussion, it is essential to d ifferentiate between four d ifferent con di- tions that may exist when we encounter a dentition that includes certain deciduou s teeth, inco nsistent with the patient's chrono- logic age. Becau se the ensuing classification of these con dition s is treatment oriented, the labelli ng of a patient with in one of these groupings indicates the treatment that is required. A late-de7.'t'/oJ'ifl~ dentition, The dental age of the pa tien t lags behind the chronologie age, as witnessed radiographica lly by less root forma tion than is to be expec ted at a given age, in the entire dentition. Typ ically, this will be evident clinically by the continued and symmetrical pres- ence of all the deciduous molars and cani nes on each side of each jaw. Extraction of deciduous teeth is con- traindi cated at this time. 2 Goer-retained deciduous Ict'/II. The dental age of the pa tient ma y be posit ively corre- lated wit h the chronologie age, bu t the radi ograph shows an ind ividual perma- nent tooth or teeth with well-developed roots, which rema in unerupted. This tends to be localized in a single area and may be due to an ectopic siting of the per- manent tooth bud, which has stimulated the resorption of only a po rtion of the roo t of its deciduous predecessor, bu t
  12. 12. 6 shedding has not occurred becau se of the persistence of the remaining part of the root or of a second and unresorbed root. Nevertheless, the condition may occa- sionally be fou nd symmetrically in a single den tal arch or in both arches. Extraction of the over-reta ined teeth is indica ted. 3 A normal del/falase, with si/Igle or multiple late-dt'!.t'lopil/g p CrIIJr1I1t' lI f leeth. This condi- tion is commonly found in relation to the maxillary lateral incisor and the man- dibular second premolar teeth. and ex- traction of the deciduous pred ecessor is to be avoided. -t A combination of the abooe. Sometimes one may see featu res of each of the above three alternat ives in a single dentition. The im po rtance of interpreting the d ifferen- tial diagnosis for a given patient cannot be overemphasized, since it ha s far-reaching effects on all the as pects of diagn osis, treat- ment planning and treatment tim ing for cases with impacted teeth. WHEN IS A TOOTH CONSIDERED TO BE IMPACTED? From the work of Oren (1962), we learn that under normal circumstances a too th erupts with a developing root and wit h approxi- mately three-qua rters of its final roo t length. The mandibular central incisors and first molars haw marginally less root develop- ment and the mand ibular canines an d second molars marginally more when they erupt. We may therefore take this as a d iagnostic base- line from which to assess the er uption of teeth in general. Thus, should an erupted tooth have less root development (Fig. 1.7), it would be appropri ate to label it as prematurely erupted. This will usually be the consequence of early loss of a deciduous too th, particularly one whose extraction w as dictated by deep caries, with resultan t pe riapical pathology. At the opposite end of the scale. we find the unerupted tooth that exhibits a more com- pletely developed root. The normal eruption process of this tooth must be presumed to THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH ha ve been impeded by one of several actio- logic possibilities. These include such factors as a failure of resorption of the roots of a deciduous too th, an ab normal eruptive pa th, a supernumera ry tooth, dental crowding or a disturbance in the eruption mechan ism of the tooth. However, obstruction may also res ult fro m a thickened post-extraction or post- trauma repair of the mucosa (Figs 1.8<1, b). Not infrequently, and particular ly in the mandibular premolar region, there may be a history of very early extraction of one or both deciduous molars. Delayed or non-eruption of the premolars will occur, owing to a thick- ened mucosa overlying the teeth. It may be possible to pa lpate these teeth, their distinct ou tline being clearly seen bulging the gum for a pe riod of year or more, although eru ption may not occur. IMPACTED TEETH AND LOCAL SPACE LOSS A time lapse exists between the pe rformance of a surgical procedure to remove the cause of an impaction and the full eruption of the im pacted tooth into its place in the dental arch. The extent of this time span is de pen- Figure 1.7 The left mandibular premolars are prematu rely eru pted. ....ith insufficient root d...vclopment.
  13. 13. GENERAL PRINCIPLES RELATED TO THEDIAGNOSIS AND TREATMENT OF IMPACTED TEETH 7 (.) (b) Figun"1.8 (a) Th~· right mandibular second premolar was extracted at age 8.5 y l',lfS. (b) Seen ill age 11. the rool of the unerupted firsl premolar is alm ost completed . dant on several factors, such as the initial dis- tance between the tooth and the occlusa l plane, the stage of the develop ment of the particular tooth, the age of the patient, andthe manner in which hard and soft tissue may be laid down in the healing wound. During this lime period, therefore, local changes in the erupted dentition may occur as a result of the break in the integrity of the dental arch caused by the surgical procedure, such as space loss and tipping of the adja cent erupted teeth. This inte rvention is no less susceptible to the drifting of neighbou ring teeth than is any other factor that may produce interp roxi- mal loss of dental tissue. With an odontome or supernumerary tooth in the path of an unerupted permanent tooth, vertical (and sometimes mesial or distal or buccal or lingual) d isplacement of the per- manent tooth is likely to be considerable. It would be convenient if the removal of the space-occupying body cou ld be performed, leaving the deciduous teeth intact, since the deciduous tooth would maintain arch integrity duri ng the extended period of time needed for the permanent tooth to eru pt nor- maUy. Unfortunate ly. often, in order to gain access to perform the desired surgery. one or more deciduous teeth need to be extracted. This being so. and having regard for the long distance that the displaced permanent tooth has to tra vel. space maintenance should be rega rded as essential in most cases. It should be the first orthodontic procedure to be con- sidered in these cases and it should be retained until full eruption has occurred. Impacted teeth are often associated with a lack of space in the immed iate area. This is frequently due to the drifting of ad jacent teeth, although crowd ing of the dentition in genera l may be the prime cause. In such cases, the spontaneo us eruption of an impacted tooth is unlikely to occur unless adequate or, preferably, excessive space is provid ed. It would be convenient if the exci- sion of the associated pathologic entity could be comfortably delayed un til this time, to bring about the desired eruption and to per- mit this corrective treatment to be attempted when the root development of the unerup ted tooth is ade quate. However, the surgeon will insist on removing most forms of pathology as soon as a tentative diagnosis is reached, in order to obta in exami nable biopsy material for the establishment of a definitive diagnosis. Odontomes and su pernumerary teeth aTC generally considered to be exceptions to this rule, and the timing of their removal may be more leisu rely considered.
  14. 14. 8 WHOSE PROBLEM? Patients do not go to their dentist com plain- ing of an impacted too th. They are frequently unaware tha t this abnormality exists, since there is no pain, discomfort or swelling. Neither is it obvious to the layman that there is a miss ing tooth, since the deciduous pred e- cessor is usually retained. The vas t majority of impacted teeth come to light by chance, in rou tine dental exa mina tion, and are not the result of a patient's direct complaint. As a general rule, it is the paedodontist or general den tal practitioner who, during a routine dental examination, discovers and records the existence of an over-retained deciduous tooth. A periap ical radiograp h will then confirm the diagnosis. There are two principal excep tions where an abno rmal appearance may be the reason why the patient seeks professional advice. The first usually' brings the patien t to the office at the age of 8-10 years, when a single maxilla ry central incisor will have erupted a yea r or so earlier and the paren t points out that the erupting lateral incisor of the oppo-- site side has not left enough space 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 parent has recognized abnormality, but will not generally have the technical understand ing to suggest the possibility of impaction of the unerupted central incisor. Figure 1.9 Unerup ted right maxil1<lry central incisor with spaa' loss. THE ORTHODONTIC TREATMENT OF IMPACTED TEETH The seco nd exception occu rs with a 14--15- year-old patient who requests the restoration of an unsightly carious lesion on a retained maxillary decid uous canine. Gene rally speak- ing. the patien t will be unaware tha t this is not a permanent tooth, and it will require suitable professional advice to point ou t that restora- tion is probably no t the appropriate line of treatm ent, rather extraction and the reso lution of the impaction of the permanent canine. A very small percentage of cases may be seen initially by their genera l denta l prac- titioner because of symptoms related to relatively rare complications of im pacted teeth. Among these symptom s arc mob ility or migration of adjacent teeth (due to roo t resorption), painless bony expansion (dentigerous or radicular cyst), or perhaps pain and I or discharge (infected cyst, with commun ication to the oral cavity) (Shafer et al.1983). Initially, the practition er should ascertain whet her there is a good chance that resolution will be spontaneous, on ce the aetiologic factor has been removed, or whether active appli- ance therapy w ill be needed. To be in a posi- tion to do this, the exact position, long-axis angulation and rotational status of the tooth have to be accurately visualized and an assessment of space in the arch must be made. Followi ng this initial assessment, the pedodontist or general de ntal practitioner now has to decide who should treat the prob- lem. Many general practitioners will prefer not to accept responsibility for the case, and wi11 refer the patient to an oral and maxillofacial surgeon, on the basis that surgery will be needed. Many surgeons will agree that the problem is essentially surgical in nature, and will proceed to remove retained deciduous teeth, clear away othe r possible aettologtc fac- tors, such as supernumerary teeth, odon- tomes, cysts an d tumours, and will also expose the impacted permanen t too th. If the impacted tooth is buccally located, the surgi- cal flap may be apica lly repositioned, to pre- vent primary closure and to ma intain subsequent visua l contact with the impacted too th after healing has occurred. This will have the effect of encouraging eruption in
  15. 15. GENERAL PRINCIPLES RELATED TO THE DIAGNOSISAND TREATMENTOF IMPACTED TEETH 9 many cases. Until hea ling (by 'secondary intention' ) has occurred, the wound will usu- ally be packed with iodoform gauze impreg- nated with Whitehead's varnish, over a period of a few weeks. Ca reful placement and wed ging of the pack between an impacted tooth and its neighbour is used by surgeons to help free the tooth to erupt na turally, when the pack is later removed. Often, in more dif- ficult impactions, wider surgical exposure is undertaken, including fairly radical bone resection, both around the crown and down to the CEl, with complete removal of the den- tal follicle. Following a period of many months and (for some more awkw ardly positioned teeth) sometimes extending into years, the surgeon will usually then follow up the spontaneous eruption of the impacted tooth until it reaches the occlusal level. If, at that tim e, alignment is poor or the tooth still has not erupted, the patient will be referred to the orthod ontist. The paed od on tist or general dental practi- tioner may alternatively and preferably refer the patien t di rectly to an orthod ontist. Cer- tainly, the orthod on tist cannot d irectly influ- ence the position of the impacted tooth until appropriate access has been provided surgi- cally and an attachment has bee n placed on the tooth. Nevertheless, with proper planning and management, including the referral for surgical exposure at the appropriate stage in the treatment, a much higher level of quality care may be provided and in a very much shorter time frame . This will be discussed in the ensuing chapters of this boo k. THE TIMING OF THE SURGICAL INTERVENTION From the above discussion, we see that the timing and nature of the surgica l proce- dure are determined by the degree of devel- opment of the teeth concerned at the time of initial diagnosis. At an early stage, a radiographic survey of a very yo ung child may reveal pathology, such as a supernum- erary tooth, an odontome, a cyst or benign tumour, that appears likely to prevent Figu re 1.10 A midline supernumerary tooth (rnesiodens] discovered in routine periapica l radiographic view of the maxillary incisor area. the normal and spontaneous eruption of a neighbouri ng tooth. At this stage, from every point of view, it would be inappropriate to expose the crown of an immature too th. In the first place, one would no t want to encourage the toot h to erupt before an adequa te (half to two-thirds) root length had been produced. Secondly, at this early stage of its development. the tooth cannot be considered as impacted , and, given time and freedom to manoeuvre, will prob- ably eru pt by itself. Early exposure risks the possibility of damage to the crown and to the subsequen t root development of the tooth. Nevertheless, with the discovery of the pathological condition (Fig. 1.10), the pot en- tial for impaction exists, and leaving the con- dition untreated will worsen the prognosis. Accord ingly, removal of the pa thological entity, withou t disturbing the ad jacent pe r- manent teeth or the ir follicular crypts, should be the aim of any treatment at that time. It may then reasonably be expected that normal development and eruption will occu r in the fullness of time. Whilst this is an obviou sly desi rable course of action, access to the tar- geted area may be thwarted by the presence and closeness of adjacent developing struc- tures, and delay may still be advised.
  16. 16. THE ORTHODONTIC TREATMENT OF IMPACTED TEETH10 _ _ _ _ _ _ __ _ _"-'----'-'-C----"----=---=--'--------=--=::..--=..'- Figure 1.11 Thl' p,lO<Jramic rad iugraph shows erup ted maxillary lat- eral incisors and over-retained d.'cid" ous ..ental incisors. TI1<.' unerupted central incisors may be seen superiorly to the two unerupted supernumerary teeth. (Courtesy of Dr I Gi 11i~. ) The second scenario occurs when the con- dition is only discovered much later. In this case (Fig. 1.11). the permanent teeth may jus- tifiably be defined as impacted, and the aims of surgical treatment become twofold: first, to eliminate the pathology, and then to create op timal cond itions for the eruption of the per- manent tooth, which is alread y late. This will usua lly involve exposure of the crown of the tooth. For many teeth, given adequa te space in the dental arch and little or no disp lace- ment of the impacted toot h, spontaneous 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, or it may no t occur in a reasonable time frame, often because of severe displace-- ment of the affected tooth. For these cases, the natural erup tive potential of the tooth is supplemented and, if necessary, diverted mechanically, with the use of an orthodontic appliance. PATIENT MOTIVATION AND THE ORTHODONTIC OPTION Angle's Class II ma locclus ion is present in between one-fifth and one-quarter of the child po pulation 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 any given orthodontic practice will reveal around three-quarters of the pa tients being treated for this ma locclu- sion. The reason for this has to do wi th the fact that a pa tient's appearance is adversely affected to a greater extent by this condition than by most oth ers. In other words, appear- ance plays an inordina tely large part in the initiative and motivation on the part of the paren t of a young pa tient to seek treatmen t. A signi ficant section of the remaining quar- ter of the patients in this hypothetical ortho- dontic practice are being treated for various less unsightly conditions (crowding, single ectopic teeth, open bites or class 3 relation- ships). This leaves on ly a few pa tien ts in this practice sample who have been referred for strictly health reasons, which may not be obvious to the pa tient. Appearance is not a problem for this small gro up of patients, wh o will have ag reed to orthodontic treatment only after motivation has been evoked by the careful and persua- sive explanations of a dentist, orthodont ist, pe riodontist, prosthodontist or oral surgeon, regarding the ills that are othe rwise likely to befall them and their dentitions. Most impactions arc symptomless, and, aside from maxillary central incisors, do not usua lly present an ob vious abnormal appear- ance. Accordingly, mo tivation for treatment in these cases is minimal, and much time has
  17. 17. GENERAL PRINCIPLESRELATED TOTHE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH 11 to be spent with the patien t before he or she agrees to trea tment. The story does no t end there, since these pa tients ma y often require periodic 'pep talks' to ma intain their level of cooperation and their res ol ve to complete the treatment. Many of them will no t maintain the required standa rd of oral hygiene, and, while it is difficult to justify continuing treat- ment in these circumstances i ~ is just as diffi- cult to remove applian ..o.:'~ rrom a patient in the mid dle of treatment, when impacted teeth have been pa rtially erupted and large spaces are present in the dental arch. For these rea- sons. while ambitiou s and innovative treat- ment plan s may be suggested , it is essential to take the moti vation factor into account before advis ing lengthy and com plicated treatment, since the risk of non-completion may be high. REFERENCES Brin I, Becker A, Shalhav M (1986) Position of the maxillary permanent canine in relation to anomalous or missing lateral incisors: a popu- lation study. Ellr / Orthod8: 12-1 6. Di Hi,lSC DD (1971) The effects of variations in tooth morphology and position on eruption. Dellt Pmct Dent Rec 22: 95-108. Gam SM, Lewis AB, Vicinus JH (1963) Third molar polym orphism and its significance to denta l genetics. JDelli Rt'S42: 1344-63. Gran A·M (1962) Pred iction of tooth emer- gence. JDCllt Res 41: 573-85. Koyou md jisky-Kaye E, Bares M, Grover NB (1977) Stages in the emergence of the denti- tion: an improved classification and its appli- cation to Israeli children. Growth 41: 285--96. Krogm an WM (1968) Biological timing and the den tofactal complex. J Dent Child 35: 175-85. Massier M, Frankel JM (1951) Prevalence of malocclusion in child ren aged 14-18 yes. Am J Ortnod37: 751-60 Mitchell L, Bennett TG (1992) Supernumerary teeth causing delayed eru ption - a retrospec- tive study. Br JOrt}IOO 19: 41-6. Moorrees CFA, Fanning EA, Oren A-M, Lebret L (1962) The timing of orthodontic treatment in relation to tooth formation. Trans Eflr Ortnoa Soc 38: 1- 14. Moorrees CFA, Fanning EA, Hunt EE Jr (1963) Age va riation of formation stages for ten perma nent teeth. JDellt Res 42: 1490-502. Nella CM (1960) The development of perma- nent teeth. / Dent Child 27: 254- 66. Schour I, Messler M (1941) The development of the human den tition. J Alii Dent Assoc 28: 1153-60. Shafer WG, Hinc MK. Levy BM (1983) A Texbook of Oral Pathology, 4th edn. WB Sau nders, Philadelphia. Sofaer JA (1970) Dental morphologic varia- tion and the Hardy Weinberg law. J Dellt Res 49(Suppl), 1505.
  18. 18. 2 RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH CONTENTS • Qualitative rad iography • CT scanning It is not the purpose of this chap ter to present a complete manu al on dental radiography, but rather 10 concisely highlight those tech- niques an d meth ods tha t are useful in the clinical setting, as it pe rtains to impacted teeth. The methods offered have two main aims (Sewa rd, 1968; Hunter, 1981). The first relates to the furnishing of qualitative infor- mation regarding no rmal and abnormal condi tions that may be associated with unerupted teeth. Thu s the different ways of radiologically displ aying and recognizing pathological entities, such as supernumerary teeth, enlarged eruption follicles, odontomes, root resorption and other pathological enti- ties, arc discussed and compared. The second aim is to describe the var ious radiological techniques that the clinician may find helpful in accurately pinpointing the position of a clinically invisible, unerupted tooth. The rela- tive merits of these techniques are discussed, and indications for their use arc suggested in relation to the different groups of teeth involved. • Three-d imensional diagnosis of tooth po sition QUALITATIVE RADIOG RAPHY Periapical radiographs The first, simplest and most informat ive X-ray film is the pe riapical view. This view is orien- ted to pass through the minimum of sur- rounding tissue. in order to give accuracy and quality of resolut ion. It is generally aimed to be perpendicular to an imaginary plane bisecting the angle between the long axis of an erupted tooth and the film plane, to pro- duce the minimum of distortion. The penapt- cal 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 will be immediately obvi- ous if there is an impacted tooth and if its stage of development is similar to that of its erupted an timere, with at least two-thirds of its root length. The presence and size of a fol- licle will be obvious, and it will be possible to asce rtain crown or root resorption, root pat- tern and integrity. The presence and descrip- tion of hard tissue obstruction will be evident, allowing the observer to distinguish connate, inrisiform and barrel-shaped supernumer- aries, and odontomes of the complex or
  19. 19. THE ORTHODONTIC TREATMENT OF IMPACTED TEETH14 ...::.::.:::...::.:==:::...:.==::.::-=..:==::::..:.:::.::.: com pound composite types. Similarly, it will show soft tissue lesions, such as cysts. The great clarity offered by the view is superior to that of other views, and it should always be used as the initial film of a suspected impacted tooth in a radiographic exam ina- tion. As with any radiogra phic film, however, the periapical view is only twa-di mensional, and gives no information in the bucca-lingual plane; overlap ping structures cannot be differentiated as to which is lingual and which buccal. For this film to give the most advantageous view of the teeth in the maxillary arch and in the mandibula r anterior segment, the central ray of the periapical view is oblique, and will vary between 20° and 55° to the occlusal plane (Mason, 1982), depending upon the region to be x-rayed. Given this oblique direction, any attempt to estimate the height of the tooth or its bucca-lingual orientation. without additional information, must fail. When performing periapical radi ography on the posterior teeth in the mandibular arch, however, the most advantageous direction has the central ray very close to the horizon- tal, and, as such, also offers a true lateral view of these teeth. Thu s not only will the observer see the most precise de tail of the tooth and its surrou nding tissues, but it will also be possi- ble to accurately assess its height in the jaw. Occlusal radiographs Mandibular arch In the mandi bu lar arch, this view is properly executed by tipp ing the patient's head back- wards and pointin g the X-ray tube at right- angles to a film, held between the teeth, in the occlusal plane (Fig. 2.1). In the lower canine / premolar region, the occlusal view is a 'true' occlusal view and sho uld depict all the posterior standing teeth in cross-section. As such, it should also provide bucco-lingual positional information on the tooth and any associated structu res in a plane at right angles to that seen on the periapical film. Because of the thickness of bone traversed, detail is mu ch poorer, unless there is expansion due to Figure 2.1 Taking a true occlusal view of the lower jaw: for the canine/ premolar region and for the incisor region. a large cyst or bucca-lin gually displaced tooth. In order to produ ce a true occlusal view in the anterior region of the mandibu lar arch (Fig. 2.1), the head will need to be tip ped back further and the tube pointed at the symphysis menti, at an angle of 110° to the horizontal, 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 aug- mented by a 15° medial tilt of the tube, to compensate for the characteristic slight lin- gua l tipping of these teeth (Mason, 1982). Maxillary arch Maxillary anterior occlusal. In the maxillary arch, the nose and forehead interfere with 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 anterior maxillary occlusal view of the teeth, which is perhaps better described as a high or steeply-angled periapical view (Fig. 2.2). The view will 'shorten' the actual length of the roots, bu t it will be a far cry from the cross- sectional view that is so easy to achieve in the mandibular arch. Since the central ray passes
  20. 20. RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH 15 !JiJ !J" Occtosat ~ " plane Figure 2.2 A diag ram showi ng incisor inclination, film pos ition and central X-ray beam, differentiating the periapical " lew, the anlt'rior (ob lique) occlusal view and the true verte x occlusal views. Figure 2.3 A trw.' vertex occlusal film using On g's pmjl'rtion, show- inll) two palatal canines. The right canine is ChlSl' to the arch and almost vertical. The crown of the Il'fl canine reaches the midline sut ure, while the Toot apex is close to the line of the a rch. anterior teeth will be seen in their cross- sectional view as small circles with a tiny con- centric circle in the centre, denoting the pulp chamber. No information is available regard- ing 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 appear within this arc of small circles. If the tooth is at an angle, not parallel to its neighbours, it will show up inits elliptical, oblique cross-section, repres enting a tilted long nxis. If the tooth is horizontal across the palate, its full length will be obvi- ous on this view, together with the exact mesio-distal and bucco-lingual orientation of both the root and the crown, in the hor izontal plane (Fig. 2.3). The difference between the two types of occlusal film may not seem to be very great, but it should be app reciated that, from the vantage point of an anter ior occlusal film, the anterior tee th will be foreshor tened but will still have appreciable length. In this situation, a high and mesially placed labial canine could give precisely the same picture as a low and mesially placed palatal canine. This could not happen in a vertex occlusal projection. Periapical Anterior occluul (60" to ccchrsal plane) Vertex occluuJ (110" to occluu l plane) through less thickness of bone, detail is usu- ally good, although not as clear as with the periapical view. True (ixrtex) occlusal. A true occlusal view of the anterior maxilla is a view in which the central ray of the X-ray beam runs parallel to the long axis of the centra l incisors (Fig. 2.2). This is only possible when the cone is placed over the vertex of the skull, to produ ce the vertex occlusal film. Since the beam has to travel a great distance through the cranium and its contents, the base of the skull and the maxilla, there is a considerable loss in clarity. Recently, an excellent method of prod ucing this view extra-orally has been described (Dog. 1994). In order to avoid the need for a very long exposure, a fast film should be used in a cassette with intensifying screens. For these reasons, the method is not popular. Nevertheless, in this view (Fig. 2.3), all the
  21. 21. 16 THE ORTHODONTIC TREATMENT OF IMPACTED TEETH (a) Ie) Ibl [dl [e) Figure 2.-1 (a) The periapical view shows an Impacted Ie-ft maxillary central incisor, due to an inverted unerupted sup,'munwr,uy tooth. The deciduous tooth is over-retained. Accu rate diag nosis of the hd~ht of the im p.1(il'd tooth in thc, alveolus is not possible from this view. (b) The anterior maxilla, seen on oil lateral Cl.'phaluffielric radiograph. shows the high impil(tN central incisor, facing the labial sulcus; Ic) and (d) representtf c SolID,' views a" (a) and (h) after removal of the SUf"?T- numeral)' tooth and bracket bonding to the exposed incisor. (Courl.~y of Dr D Harary.I (e) A pa rallel intra-oral photo- gra phic view. This film has been lM"rally inverted to simplify comparison.
  22. 22. - RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH 17 Extra-ora! radiographs The panoramic view, while not showing the same degree of detail as a periapical film, has the advantage of simply and quickly offering a good scan of teeth and jaws, from TM joint to TM joint. It is probably true to say that orthodontists are tod ay in general agreement that this film gives the most qualitative infe r- mation. to act as a starting point from which to proceed to other forms of radiography, in line wit h the demands of the pa rticular situ- ation in any given case. True and oblique lateral extra-oral views (Figs 2.4a-e) and the va riously angulated oblique occlusal films all provide information that may be used to complement the periapi- cal film, particularly when tooth displace- ment is severe. However, the use of any oblique film for the accurate localization of a buried tooth may frequently be misleading, be it a single pe riap ical, an occlusal or a lat- eral jaw film. This being so, two incipient dangers exist. First, as we shall see in later chapters, a surgical procedure may be mis- directed and a flap opened on the wrong side of the alveolar process. Second ly, misinterp re- tation of the too th's position may lead the operator to assume a very favou rable progno- sis for biomechanical resolution when, in fact, the tooth may be in a completely intractab le position. Thus the choice of treatment will be inappropriate. THREE-DIMENSIONAL DIAGNOSIS OF TOOTH POSITION As dentists, we arc very used to seeing peri- apical films of individua l teet h, and, prov ided that the teeth concerned are in the line of the arch, these films have many advantages. However, in this view, the x-ray tube is not directed in the true horizontal, true vertical or true lateral planes. Aside from radiography of the mand ibular posterior teeth, the tube is always tipped at an angle to one or more of these planes. Th is is unimportant for an eru pted tooth, since the third di mension is supplied by the di rect vision within the mouth. Thu s, while it gives a good two- dimensional representation of the tooth, this view has limited value when vis ualization of an unerupted tooth is req uired, in the three planes of space. PARALLAX METHOD By following the principles involved in binoc- ular vision, two pe riapical views of the same object and taken from slightly different angles can provide de pth to the flat, two-dimensional pictu re depicted by each of the films individ- ually (Fig. 2.5). This is of considerable help with distinguishing the bu ccal or lingual dis- placement of the canine, which is low down and fairly close to the line of the arch. The procedure is performed in the following man- ner (Fig. 2.6). 1 A periapically sized film is placed in the mouth, with the patient's finger holding it against the palatal as pect of the area where the too th would normally be situ- ated. The x-ray tu be is directed at right- angles to a tangent to the line of the arch at this poi nt, as for any periapical view Figure 2.S The left periapical view. oriented for the central incisors, shows the crow n of the camne superimposed on the dis- tal half of the central incisor mot. Th~' rmddlc film, rotated 30" to the left, shows the canine overlapping only the lateral tnctsor roo t. By mlaling the cen tral beam ,1 fur - ther 30", superimposition of Itll' canine over the lateral incisor root has been eliminated. The canine is pilloltally displaced.
  23. 23. THEORTHODONTIC TREATMENT OF IMPACTED TEETH18 - - - - - -- - - - ----'-'-----'---------'------ Figure 2.6 A d iagra mmatic representanon of the parallax method. If the ll.~·n·d~ '-'yt' p''t.'n; along the axis of the X-ray beam in each Col"". the image on lilt>film will be easy to I'CUJ15truct. and at the appropriate angle to the hori- zonta l plane. 2 A second film is pla ced in the mouth in the identical position, bu t on this occasion the X-ray tube is shifted (rotated) mesi- ally or distally round the arch, but held at the same angle to the horizontal plane plane and di rected at the mesially or dis- tally adjacent tooth. To achieve this, the tube should describe between 30° and 45° of an Me of a circle whose centre is some- where in the middle of the palate. Let us assume tha t a right unerupted canine is pa latally pla ced (Fig. 2.6), then this tooth will be close to the middle of the picture obt ained in both films. However, in the first pictu re, where the tube was directed over the designated canine area of the ridge, the lateral incisor root will be on the right. If the cani ne is also well forward, the re will be some over- lap of the canine crown an d the lateral incisor root. On the seco nd picture, taken from the 23 21 2 23 21 fron t, the right lateral incisor root and the crown of the palatal canine will be in the mid- dle, superimposed on on e another to a much greater degree. Jacobs (1986, 1987) enjoins the obse rver to use the right eye in place of the x-ray tube and suggests the useful exercise of hold ing up two fingers vertically at eye level, with one obscu ring the other. If the observer now closes th is eye and opens the other, his or her new vantage poi nt for inspection will have resulted in a visual separation of the two fin- gers. Through the left eye, the obscured finger will ha ve 'moved' to the left of the forward finger, to become partially visible. Trans- ferring this to the radiographic context, in the second picture, the tooth furthest from the tube [l.e. the palatal toot h) will 'move' in the same direction that the X-ray tube has trav- elled from the first exposure. This method is very useful in cases where there is a minim al height discrepancy be- tween the erupted and uneru pted adjacent teeth (Fig. 2.5). However, when the canine is high and the periapical view shows no supe r- imposition of the canine with the roots of the erupted teeth, or where the superimposition is only in the apical area, then the overall pic- ture may be very mislead ing and a different method of localiza tion should be used. The periapical view is direc ted from above the occlusal plane an d in an oblique downward and medial direction, which distances the palatal canine from the roots of the othe r teeth and makes it appear higher than the anatomy of the maxilla would allow. Tn the incisor region, an unerupted perma- nent incisor may be associated with one or two supernumerary teeth (meslodcns) . The parallax method is insufficiently clear in these cases, because of the presence of two or three hard tissue entities in the bone, superimposed on the outline of the root s of the decid uous teeth and at varying heig hts in the alveolus. Radiographic views at right-angles Radiographic views may be taken at right- angles (Seward, 1968; Hunter, 198] ) to one
  24. 24. - RADIOGRAPHIC METHODS RELATED TOTHE DIAGNOSIS OF IMPACTED TEETH 19 (.) (b) «) Figure 2.7 (a) The trw lateral cephalometric radiograph shows both canines superimposed, ill a higher levelthan th., other Il'CIh. Their axial inclination in the aotero-posterior plane is favourable, with the crowns and "'pin'S apparontty normally located . (b) The pos tero-anterior cephalometric radiograph 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 that the apices art.' ideally ploln-d and that the long ""lOS of the It...·!h hav e a downward, mesial and palatal inclinil(ion. (0;:) The panoram ic -il' W of the same pati.'nl. Th., apF"'arancc of canines c!0S<' 10 the midline is very simil.u ttl that .......n on th.· pos tero- anterior ccphalomcutc radiograph. another in various ways, but, for the method to be of value, it must be possible to deter- mine the exact orientation in space of both the film and the central ray, by observing other structures on the film. This requirement is very difficult to satisfy when a view is sought at right angles to the periapical view. Standardization, w hat is requ ired is the standardization of views within the confines of a strict adherence to the planes of space. A true lateral view (Fig. 2.7a) will give exact infor- mation regarding both the antero-posterior and vertical location of an object, relative to other structures that may be seen both on that radi- ograph and clinically. It will not give any clue to the bucco-hngue l (transverse-plane) pic- ture. A true occlusal view will provide posi- tional information in both the antero- posterior and transverse planes, but not the vertical plane. The third possibility is the true postero-anterior view (Figs 2.7b,c), which defines the height (vertical plane) and the bucco-Hnguel relatio nship only. By combin- ing the results of any two of these three films, three-d imensional localization may be accu- rately determined . Translating these principles into radio- graphi c practice presents some difficulties. However, these arc not insurmoun table and, insofar as they present the clinician with accurate positional visualization of the unerupted tooth, they arc entirely worth- while. In the rnandibulnr posterior area, we have pointed out that the routine periapical radio- graph is also a true lateral view, with the X-ray tube pointing at right-angles across the body of the mandible, in the horizontal plane. The height and mesio-distal position of a buried tooth may then be accurately defined. The occlusal rad iograp h of this area is d irected at right angles to the occlusal plane, and adds the bucco-Hngual dimension to complete the three-dimensional picture.
  25. 25. THEORTHODONTIC TREATMENT OFIMPACTED TEETH 2O ~=~===~== ===_'_ (. ) (b) Hgure 2.8 The tru e lateral and true occlusal views, taken tog eth er, provide all the info rmation needed for an accurate positional assessment of crown and root in the three planes of space. (ill The peria pical view (a true lateral in this case) of an impacted mandibular right second premolar shows the tooth to be tipped distally 60" from the vertical. with its incom- plete apex at the correct height and mesio-dis tallocaticn. (b) The true occlusal view shows 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 ideally sited i1f'l'J(, may be described as rising at a 30" an gle in a dis tal and lingua l direction, 10 oVl'rlap the molar roots on the lingual side. Accordingly. these two views will provide accurate localization of the position of unerupted tee th in this area (Fig. 2.8). For most orthodontic cases, the lateral cephalometric radiogra ph is an essential prerequisite and, aside from the routine mea- surement of angles and planes, this film should also be used to gather valuable infor- mation regarding 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 par- ticular (Fig. 2.7a). Although there arc many superimposed structures on this area, the out- line of a canine may be clearly seen. The direction of the long axis of the tooth in the antero-posterior and vertical planes may be defined, together with the mesiodistal posi- tions of both crow n and apex. If a cephalometric radiograph is not avail- able, the same view of the anterior maxilla may be obtained on an occlusally sized film. This film is held vertically against the cheek and parallel to the sagittal plane of the skull. The X-ray tube is directed horizontally above and parallel to the occlusal plane from the opposite side of the face, and at right-angles to the film. The result is called the tangential view and has the advan tage of simplicity. This view is particularly useful in monitoring progress in the resolution of impacted incisors during active treatment. At the age at wh ich most patients first pre- sent with an impacted central incisor (around 8- 10 years), the permanent canine teeth are unerupted and are located both well forward and high in the anterior max illa. Thus, on the lateral cephalometric or tangential view, right and left canines will be impossible to d ifferen- tiate individually. The roots of the incisors, at the same height as the canines, as well as the superimposed images of the more inferiorly placed crow ns of the erupted incisors and deciduous canines, will all be indistinguish- able from one another and from supernumer- ary teeth that may also be present. For this
  26. 26. RADIOGRAPHIC METHODSRELATED TO THE DIAGNOSIS OF IMPACTED TEETH 21 Figure 2.9 A dilacerated cent ral incisor so-en in the lateral o.'phalo- mctric rad iograph. reason, the lateral view may be of limited value in cases where there is obst ructive impaction. with minimal displacement. When gross displacement is present, however, the outline of the altered axial inclination and- height of the tooth can usually be delineated, despite the considerable superimposition of other teeth. Nowhere is this view a greater asset than when a dilacerated tooth is present, since it separates out this malformed tooth, superi- orly, from the root apices of the other teeth and from the permanent canines, because of its relative height (Fig. 2.9). Furthermore, its morphology may be seen to best advantage from this aspect, wh ich allows definitive and accurate diagnosis of the condition to be made, together with its precise relations vis-a- vis surrounding structures. The tangential view should be considered an essential requirement in radiographically recording the dtlaccratcd central incisor. For maxillary canines, the lateral view is extremely useful. It should be remembered that most impacted maxillary canines are diagnosed in the full permanent dentition, when all the other tee th will have erup ted. This demarcates the canine at a higher level than the other tee th. A postero-anterior cephalometric film is used less rout inely in ort hodontics, bu t it offers the clinician the oppor tunity to view the maxilla in a d ifferent plane, the true postero-anterior view (Fig. 2.7b), which is at right-angles to the lateral cephalogram. The overlap of structures of the base of the skull and the maxilla renders detail of ind ividual teeth less clear, but a good pos tero-anterior radiograph will show the height of both the crown and the root of a markedly displaced tooth, as with the lateral fil m. This view also shows whether the root apex of an ectopic pos terior tooth is in the line of the arch and how far the crown is deflected in the palatal direction. The bucca-lingual tilt of the long axis of the tooth will be plainly visible (Fig. 2.10). However, the view is less practical in the mandible, where the body is oblique to the central ray. There is usually excessive overlap, more radio-opaque bone and diffi- culty in discerning even markedly bucca- lingually displaced teeth. An occlusal projection of the anterior max- illa (Fig. 2.3) offers the possibility to view in the third plane of space, at right-angles to each of the two earlier rad iographs, and to record the position of the displaced incisor or canine without overlap . However, for it to be of greatest value, it is important to project the X-ray beam through the long axis of the maxi- llary teeth, as just described. Any two of these three views (the lateral cephalogram or tangential view, the postero- anterior cephalogram and the true occlusal) will provide complete information regarding every aspect of the height, bucco-lingual and mesio-dis tal location of the crown, the root, and the degree of tilt of the long axis of the imp acted tooth and its relation with neigh- bouring teeth. The postero-anterior and occlusal views, however, arc 110t always as clear as is desirable, and they may need to be repeated or discarded . The lateral cephalo- metric or tangential views in a cast' of bilat- eral canine imp action may crea te confusion, since one canine will be superimposed on the other and distinguishing them may be a prob- lem, although other views will usually facili- tate differentiation. Two identically oriented and superimposed canines (Fig. 2.7) will obvi- ously not need to be differentiated. Fr"om these aspects, it is very easy to bu ild
  27. 27. 22 (.j « j THEORTHODONTICTREATMENT OFIMPACTED TEETH (b j Figure 2.10 (e.b] Extracted portion of the lateral and postero-anterior cephalo- metric views, to show an impacted max illary left second premolar to be loca ted with its apex in the line of the arch, but superiorly displaCl.·..t Th{' crown is displaced palatally, close to the mid line and the long axis is strongly palatal, slightly downward and slightly distal. (c) The periapical film gives the misleading appear- ana' of the crown being displaced superiorly and anteriorly. (Courtesy of Dr I Gillis.) up a three-dimensional picture of the exact position and angulation of the impacted tooth and to define the type of movement that will be necessary to bring the tooth into align- ment. When building this composite mental reconstruction of the position of the un - erupted tooth in space, the design of the appliance needed to resolve the impaction is simplified and fewe r surprises are likely to be encountered . It is, however, an important pre- requisite in all these cases to examine a peri- apical view of the tooth, to eliminate the possibility of local pathology, which could be missed on the extra-oral views. CT SCANNING Recen tly, the usc of computed tomography (CT) scanning has been suggested (Ericson and Kurol. 1988a,b) for identifying the exact position of the palatally impacted canine, par- ticularly when root resorp tion of the lateral incisor is suspected (Ericson and Kurol. 1987). cr scann ing is a method in which clear serial radiographs may be taken at graduated depths in any part of the human body (Fig. 2.11a). At the same time, this technique allows the elimination of the superi mposition of other stru ctures that we have seen will
  28. 28. RADIOGRAPHIC METHODS RELATEDTO THEDIAGNOSIS OF IMPACTEDTEETH 23 (.) (d ) (bl (el (-) Figu re 2.11 (a) The lateral skull r,ld iogr,l ph shows the direction and separation of the individ ual CT "slices', (b-e) These sections dt'pict most clearly tht' midline slIpt'm umerar y loath and its rel,ltion~hip to the adja cent teeth in all three plant'S of space. (Co urtt'Sy of Dr 0 Eiscnbud.] obscure the image of the object that we are attempting to view in trad itional radio- graphy. In recons tructive dentistry, this method has been developed to allow accura te placement of implants (Schwarz et al, 1989). Although it has excellent potential for the diagnosis of the position of impacted and supernumerary teeth, the large dosage of radiation is difficult to justify for all except the exceptional case. By viewing seria l rad iographic 'slices' of the maxilla (Figs 2.11b-c), the relationship of the impacted tooth to adjacent teet h, in all three planes of space, may be accurately assessed , as can the positions of CTOwn and apex and the inclination of the long axis of the tooth. In the following chapters, we shall describe how the relative difficulty of bring- ing these teeth into their proper position is depe ndent on advance knowledge of the exact positions of bot h crown and root apex. We sha ll conclude that variations in root apex displacement, in particular, prejudice both the ability of the orthodontist to complete the exercise and the periodontal prognosis of the tooth, when the treatment is finally com- pleted. The method may also give accurate information regarding early root resorption, pa rticula rly of the buccal and palatal su rfaces of the rool. Th is may not be possible to diag- nose by any other method, prior to treatment. It therefore makes sense that for those
  29. 29. 24 pat ients in whom there is a suspected dis- placement 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 computed tomography should be considered. Although CT scanning units are relatively few and imaging is expensive, their use is increasing. and they are now more freely available to the orthodontist in practice . It may still be difficult to justify using the method on a routine basis for the occasional and more straightforward case with one or two impacted teeth. However, its use in cases of multiple impactions, particu larly cleidocra- nial dysplasia, has much to offer in the accu- rate placing of the very large number of impacted teeth, both at the treatment plan- ning stage and the subsequent surgica l phases. REFERENCES Ericson S, Kurol J (1987) Rad iographic exami- nation of ectopically erupting maxillary canines. Am I Orthod Dentojac Orthop 91: 483-92. . Ericson 5, Kurol J (1988a) CT diagnos is of THEORTHODONTIC TREATMENT OF IMPACTEDTEETH ectopically eru pting maxillary canines - a case report. ElirI Orthod10: 115-20. Ericson S, Kurol J (1988b) Resorption of maxil- lary lateral incisors caused by ectopic erup- tion of canines. Am I Orthod Dentojac Orthop 94: 503-13. Hunter S6 (1981) The radiographic assess- ment of the unerupted maxillary canine. Br Dent 1 150: 151-5. Jacobs SG (1986) Localisation of the unerupted maxillary canine. AI/sfr Orthod 1 9: 313-16. Jacobs SG (1987) Exercises in the localisation of unerupted teeth . Austr Orthod J 10: 33-5, 58- 60. Mason RA (1982) A Guide to Dental Radiography, 2nd edn. Wright PSG, Bristol. Ong A (1994) An altern ative technique to the vertex/ true occlusal view. Am J Orthod Dentcfac Orthop106:621-6. Schwarz MS, Rothman SLG, Cha fetz N, Rhodes M (1989) Computed tomography in dental implantation surgery. Dent Clin N Am 33, 555-97. Seward GR (1968) Radiology in general den- tal practice. IX - Unerupted maxillary canines, central incisors and supernumer- aries. Br Dellt / 115:85--91.
  30. 30. 3 SURGICAL EXPOSURE OF IMPACTED TEETH In collaboration with Professor Arye Shteyer and Professor Joshua Lustmann CONTENTS • Aims of surgery for impacted teeth • Surgicallntervenlion without orthodontic treatment • The surgical elimination 01pathology • Buccallyaccessibl e Impacted teeth • Partial and fu ll flap closure on the palatal side • A con servative attitude to the dental follicle • Cooperation between surgeon and orthodontist • The team approach to attachment bonding AIMS OF SURGERY FOR IMPACTED TEETH For impacted third molars, treatment alterna- tives and opportunities for choice are few, and. in the majority of cases, extraction is advised. However, for othe r impacted teeth, this is not so, and several lines of treatment may present (McDonald and Yap, 1986). Nevertheless, in the past, the decision as to how a particular impacted tooth should be treated was most often decided by the oral surgeon, who also, by and large, decided upon and stage-managed the alternatives. This situation has changed in recent years. Prior to the 1950s, most orthodontists were unprepared to adapt their skills and ingenu- ity to the task of resolving the impaction of maxillary canines and incisors. Accordingly, the orthodontists themselves referred patients to the oral surgeon , who would decide if the impacted tooth could be brought into the dental arch. Where the circum stances were potentially favourable, the tooth would be surgically exposed, and, when the surgical field was displayed fully, the surgeon would make his assess ment of the prognosis of the case, decide and act solely in accordance with his own judgement. In this way, man y po-- tentially retrievable impacted teeth were extracted. There are no surgical methods, other than transplantation. by which positive and active alignment of an impacted tooth may be car- ried out. The best a surgeon may do is to pro- vide the optimal env ironment for normal and unhindered eruption and then hope and pray that the tooth will oblige. With this in mind, therefore, those teeth that were considered wor th trying to recover were widely exposed and packed with gauze soaked in White- head's varnish, to protect the wound during the healing ph ase and to prevent reheating of the tissues over the tooth. For a varie ty of rea- sons, several other steps were taken, depend- ing upon the preferences and beliefs of the operator, with the aim of providing 't hat extra something' that would improve the chances of spontaneous eruption still further. These measures were often very empirical in nature, and included one or more of the fol- lowing: (a) clearing the follicula r sac completely, including in the eEJarea;
  31. 31. 26 THE ORTHODONTICTREATMENT OF IMPACTED TEETH (b) clcan ng the bmw around the too th, down to the eEJ area, to dissect out a nd free the entire crown and the corona l portion of the roo t of the Impacted tooth; (c) 'looseni ng up' the tooth, by subluxa ting it wi th an elevator; (d) bone-channelli ng in the desired direc ti on of movement of the too th; (e) pocking g,l uZC or hot gutta percha into the area of the CEl, und er pressure, in order to apply force to deflect the crop- ~ tion pa th of the tooth in a particular d irec- no n. (.1 Figuree 3.1 (,1) A lo·yt'.u-ul,l k nl,llt' exhibitsan Ullt' Tuple,.I maxillary ldt canine, which 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, and Ih,· flap, whi ch co nsist,,,,l of thickened mU(O"'l. was apically repositioned . (c) At 9 mon ths post-surgery. the t"" th h,l" erupted nnrm"ll y. (Cour t,'!'>y of L Shapira.) lei W e COIllC a c ros s CilSCS in which the on ly clini- cal problem relates to the impacted tooth, the occlusion an d nllgnmcnt being otherwise acceptable. For these pa tien ts. the following question needs to be addressed : What surgi- cal methods MC available that may be expected to provide a more or less complete solution, without outside assistance? To be in a position to answer this question, it is neces- sary to provide a description of the position of the teeth that wi ll respond to this kind of treatment. SURGICAL INTERVENTION WITHOUT ORTHODONTIC TREATMENT In those years. few patients were referred to the orthodontist until full eruption had been achieved and the tooth then needed to be moved horizontally into line with its neigh- bOUTS. Up to that point. the problem was con- sidcrcd to be w ithin the realm of the oral surgeon. In many cases. 'success' in achieving the eruption of the too th was pyrrhic and often subordina ted to failure of .1 different kind . namely the periodontal condition of the newly eru pted tooth and its poorer survi val po tential - its prognosis. This was the inevitable result of the aggressive and over enthusiastic surgical techniques that had been used. which typically left the tooth with an (hI elongated clinical crown, ,1 lack of attached gingiva and .1 red uced alveol ar crest height (Odenrick MId Modcc r. 1978; Boyd, 1982, 19M; Becker ct al.1983; Kohavi ct .11, 1984a, b).
  32. 32. SURGICAL EXPOSURE OF IMPACTED TEETH (b) Figure 3.2 (a) Soft tissue impaction of max illary central incisors. (b) Apical repositioning (If bo th buccal and palatal flap s to leave the incisal edges exposed . (Courtesy of Professo r J Lustma nn.) Exposure only A superficially placed tooth, palpable beneath the bulging gum, is an obvious candidate. This type of tooth may be seen in the maxil- lary canine area (Fig. 3.1), but also in the mand ibu lar premolar area (sec Fig. 1.8) and the maxillary central incisor area (Fig. 3.2), usually where very early extraction of the deciduous predecessor was performed while the immature permanent tooth bud was still deep in the bone and unready for eruption. Healing occurred, and the permanent teeth are unable to penetrate the thickened mucosa (Dibiase, 1971; And reasen and And reasen, 199~). Removing the fibrous mucosal cover- ing or incising and resutu ring it to leave the incisal edges exposed (Figs 3.1a and 3.2b) will Figure 3.3 Following exposure and packing, tlw tooth has erupted spontan<-'(lusly. bu t thO;' bon...l...vel is compromiso."d. generally lead to a fairly rapid eruption of the soft tissue impacted. tooth, particularly in the maxillary incisor area. The more the tooth bulges the soft tissue, the less likely is a rebur- ial of the tooth in healing soft tissue and the faster is the eruption. Exposure with pack Taking this one step further, we can SI,.'C that a less superficial tooth requires a more radical exposure procedure, and may need a pack to preven t the tissues frum reheeling over the tooth. While the surgeon may be rewa rded with spon taneous eruption, this will take longer, and a compromised periodontal result should be expected (Fig. 3.3). We have defined over-retained deciduous teeth as teeth still present in the mouth when their permanent successors have reached a stage of development that is compatible with their full eru ption. These decid uou s teeth may then be considered as obs tructing the normal development that would be expected to proceed in their absence, The deciduous teeth should be extracted, but provision should be made to encourage the permanent teeth to erupt quickly. Many of these perma- nen t teeth with dela yed eruption arc obnor- mally low in the alveolus, and Me in danger 27
  33. 33. THE ORTHODONTIC TREATMENT OF IMPACTED TEETH28 ~~----------'------------'---- of being rebu ried by the healing tissue of the evacuated socket of the deciduous tooth. According ly, the crowns of the teeth should be exposed to their widest diameter an d a surgical or periodontal pack placed over them and sutured in place for 2-3 weeks. This will encourage epithelialization down the sides of the socket and, generally, prevent the re-fer- mation of bone over the unerupted toot h. Exposure with pressure pack brought about an improvement of the posi- tions of the grossly displaced teeth, together with an improvement of the bony defect that will be ev ident in the anatomy of the alveolar bone in the area, which may take ma ny months to occu r. Duri ng this time, the psy- chological preparation of the patient for the proposed orthodontic treatment may be undertaken, which must begin with seeing positive results from a preventive dental health programme aimed at eliminating ma r- gina l gingival inflammation and redu cing the caries incidence for that patient. . Mild mesial impaction of a mand ibular sec- ond permanent molar beneath the distal bulbosity of the first permanent molar is a condition that often responds to surgical interven tion and packing on ly. This involves exposure of the occlusal surface of the tooth and the deliberate wedging of some form of pack in the area between the two teeth and leaving it there for two or three wee ks. During this time, the pressure will often suc- ceed in eliciting a distal mov ement of the impacted molar, which may then erupt more freely whe n the pack is removed . The degree of control available to the operator in judging the amo unt of pressure applied and the extent to which the pack interferes periodon- tally 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 sup- porting structures in the final analysis. THE SURGICAL ELIMINATION OF PATHOLOGY Soft tissue lesions In Chap ter 7. we sha ll refer more specifically to benig n tumours. Surgical treatment is the onlv trea tment tha t is indicated for these con- diti'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 tative diagnosis. Ortho- dontic treatm en t should be suggested then - but begun only after a filling-in of bone has Hard tissue obstruction Obs tructive impaction invi tes the logical step of rem oving the offend ing body causing the no n-eruption. On many occasions, this is pe r- formed by the surgeon, without recourse to orthod ontic assistance, and enjoys a varying degree of success. ln Chapter 5, we sh,111 refer to the reliability of spontaneous eruption, following the various surgical procedures involved in the treatment of impacted incisors. For the presen t discussion, we must recogni ze that there is a significa nt number of cases in which eruption does not occur in a reasonable time frame . Undoubtedly, the position of most un- erupted teeth improves with the passage of time, following the removal of the obst ruc- tion, be it a supernumerary tooth, an odon- tome, residual deciduous roo ts or an infra- occluded primary tooth. However, many of these teeth do not erupt without assistance, because of local dis turbances caused by the recently removed obstruction and the healing tissues. A hard tiss ue body occupies mu ch spa ce, and may cause a gross d isplacement of the developing tooth bud of the norm al tooth, both in terms of overall distance from its place and in that the orientation of its long axis is also deflected. Thus the root or the crown of the tooth may be deflected mesially, distally, ling ua lly or buccally, compromising its cha nces of spontaneous eruption. Ab- normally sha ped root s may develop in the BleLJOTH~aUE' DE L'UNI'lER S rT~ C": P/I.RI S V U.r:::.R. D" '; ' : l i '--' I:" /~! ': 1,ruO :: ;:'I ,' ~r-" '{ Q ? 1 ? n ~Jl ("'III U ,,,. , <::
  34. 34. SURGICAL EXPOSURE OF IMPACTED TEETH cramped circumstances in which they find themsel ves, between the displacing influence of the pathological entity and the adjacent teeth, on the one hand, and the floor of the nose or lower border of the mandible (Becker and Shochat, 1982), on the other. Non-eruption disturbs the eruption pattern of the adjacent teeth, which then assume abnor- mal relationships to one another, usually char- acterized by space reduction and tipping. This then provides a secondary physical impedi- ment to the eruption of the impacted tooth. tntrsocclusion As we shall discuss in Chapter 7, infra- occluded permanent teeth are usually anky- lased to the surrounding bone, and, as such, cannot respond to orthodontic traction. In many cases, the ankylosed area of root is minute, and may be easily bro ken by a delib- erate but gentle luxation of the tooth. This is usually performed with an eleva tor or extrac- tion forceps, and is done in such a way as to slightly (very slightly) loosen the rigid con- (. ) nection of the bony union, which is unbend- ing. The tooth is not removed from its socket, nor is the aim even to tear the periodontal fibres. The purpose is to retu rn the tooth to the same degree of mobility that is character- istic of a normal tooth. Unfortunately, the fate of the tooth that has undergone this procedure is usually a reheal- ing and reattachment of the ankylotic connec- tion, leading to a return to the original situa tion. Accordin gly, this approach can only be successful if a continuously active traction force is applied to the tooth from the time of its luxation. This force may then act to modify the rchealing of bone, du e to the dis- tractio n osteogenesis (Ilizarov et al, 1980; Altuna et al, 1995) that it causes. If the range of force is small and loses its potency betw een visits for adjustment, reankylosis will result. Thus, to be effective, it must be of sufficient magnitude to cause distraction and of suffi- cient range to remain active between one visit for adjustment and the next. The risk is that a poor biomechanical auxiliary, insufficient force levels or missed appointm ents may cause the exercise to founder, owing to re- establishm ent of the ankylosis bridge. (b) Figure 3.-1 (al A high buccal canine exposed by circular incision of the sulcus mucosa . (b) Following alignment. the oral mucosa is allached directly to the gingiva. (Courtesy of Dr G Engel.)
  35. 35. THEORTHODONTIC TREATMENT OF IMPACTEDTEETH30 ...:...:=...:...::.:..:....:...: _ BUCCALLY ACCESSIBLE IMPACTED TEETH There are fou r met hods ava ilable to resolve an unerupted toot h that is on the buccal side of the ridge and high in the sulcus. Thcse are as follows. 1 A circular incision This may be made in the sulcus mucosa, immediately over the crown, to expose the bony crypt immediately beneath. In order to do this, the entire surgical procedure would inevitably be sited above the attached gingiva (Fig. 3.4). From the surgical point of view, suitable access will have been provided to allow the bonding of an attachment. From the ortho- dontist's standpoint. the application of light extrusive forces of good range presents no particular d ifficulties, an d red uction of the impaction may be very rapid. Whilst this may satisfy both surgica l and orthodontic demands, the periodontic result will be poor, and there will be an elongated clinical crown. The band of attached gingiva will be tu rned palatal to the aligning too th, which could create a factor for buccal posi- tional rela pse at the end of trea tmen t. On the labial side, the too th will be invested with the thin oral mucosa, which offers a poor long- term prospect under conditions of normal func tion for the fully corrected canine. In many of these cases, eruption may occur naturally, with the tooth emerging through the sulcus mucosa and above the attached gin giva. Prompt treatmen t will be needed if these teeth Me to acquire a normal periodon- tal environment, wh ich will dictate pre- empting their eruption . The circular incision method provides no solution to this. 2 Apica//yrepositioned surgical ffap This method, ., recognized and accepted pro- cedure in pe riodontics, was first described in the context of surgical and orthodontic treat- men t of uneru pted teeth by Vanarsdall and Corn (1977). In their method and in the absen ce of the deciduous can ine, a muco- gingival flap is raised from the crest of the ridge that includes attached gingiva (Fig. 3.1). If a deciduous canine is presen t, the flap is designed to include the entire area of buccal gingiva that invests it, and the deciduous tooth itself is extracted. In eithe r case, the flap is detached from the underlying hard tissue some way up into the su lcus, to expose the canine. The flap is then sutured to the labial side of the crown 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 accompa- nied by the healing gingival tissue, and, when the tooth takes up its final position in the arch, it will be found to be invested with a good width of attached gingiva. When left untreated, palpable unerupted tee th may take ma ny months to break through the mucosa and reach their final positions. Whe n an apically repositioned flap is pe rformed , eruption is speeded up. Addi- tionally, with the sutured soft tissue applying some pressure on the buccal side of the tooth and assuming there to be space in the imme- diate vicinity, a buccal displacemen t may be spontaneously reduced. If the unerupted tooth is very high, the sur- gical flap, wh ich stretches from below the attached gingiva on the crest of the ridge or at the free gingiva of the deciduous tooth up to the depth of the sulcus, would be excessively large. Under these circumstance. the proce- dure is no t recom mended, since the ap ically repositioned flap would then leave a wide area of the labial bony plate unnecessarily exposed to the oral environment. In a more recent study, Vermette et al (1995) found several drawbacks in relation to the aesthetic and period on tal results of the apically repositioned flap technique for buc- cal canines, wh ich had no t been previously reported. Tn uni laterally affected and trea ted cases, the clinical crown length was greater than the untreated control side and an uneven and unaesthetic gingival ma rgin was often produced (Fig. 3.5). There was also a
  36. 36. SURGICAL EXPOSURE OF IMPACTEDTEETH Fig uno 3.5 Uneven and un aesthetic gingival margin, bands of gingi- val sca rring and a long d ini(al (TOWn, following api(al repositionin g of the flap covering thi s form erly buccally impacted ( an ine. degree of attachment loss and bone loss on the labial surface, which was considered as possibly related to an increased. potential for plaque accumulation that the procedure seems to encourage. Vermette et al (1995) also reported a vertical orthodontic relapse in 61% of the teeth that had been erupted using orthodontic appli- ances, after treatment had been completed. They speculated that the reason for this is that, following the apical repositioning, the gingiv al tissue heals to the adjacent mucosa, producing soft tissue bands of gingival scar- ring. As the tooth is pu lled Inosally, this mUCOS<l is stretched down with it, towards the alveolar crest. This then leads to a relapse ten- dency when the forces arc released. However, the periodontal attachment was unaffected when comp ared with the unoperated control side. Nevertheless, an important advantage of the method is that the buccally imp acted canine is exposed to the oral environment, and remains accessible for attachment bond- ing. In some cases, where orthodontic treat- ment is not needed for other problems, the progress of the tooth may be followed for many months, unti l full eruption will have occurred, without the use of appliances (Fig. 3.1). In others, an attachment may be bonded by the ort hodontist at any app ropriate later date and active extrusion subsequently undertaken. 3 Full flap closure This was proposed by McBride (1979), and is a procedure that may be used rega rdless of the height of the canine. A buccal surgical flap is raised as high as is necessary to expose the unerupted canine. An attachment is then bonded to the tooth. and the flap is fully sutured back to its former place. A twisted stainless steel ligature wire that has been threaded through the attachment is then drawn inferiorly and through the sutured edges of the replaced flap, at the crest of the ridge, or throu gh the socket vacated by the extracted deciduous canine. Spontaneous eruption is less likely to occur than when the tooth remains exposed, follow- ing apical reposition ing, and active orthodon- tic force will probably need to be applied to the tooth to bring about its eruption. In this method, the tooth erupts toward and through the attached gingiva area, which then becomes attached to the tooth and the sur- rounding alveolar process. This d osed-eruption method compares fav- ourably (Vermette et al, 1995) with the api- cally repositioned flap method described above. The full flap closure method (closed eruption technique) shows no tendency for an apical and uneven gingival position, nor does it produce a long clinical crown . There is no loss of attachment on the buccal aspects, nor is gingival scarring produced with this method, and the periodontal attachment is completely normal. A further and pa rticularly significant d if- ference between the two methods of surgical exposure of the buccal canine reported in this work was that in the full closure method, there was no vertical relapse of the treated canine follow ing the completion of treatment. However, the closure of the flap at the end of the surgical stage dictates the necessity for the 31
  37. 37. THE ORTHODONTIC TREATMENT OFIMPACTED TEETH32 .::.:.-=-=.::.:....:..:.::..::.::.:.-"-==--'-=-"-=.::.:..::.:..::..::.=..::= CC Figu re 3.6 Buttonholing. placement of an attachment, while the tooth is visible and in the surgeon's operatory. It can- not be left until a subseq uent visit. The method has unequivocal advantages over the apically repositio ned flap method, and these have been attributed to the close similar- ity of the conditions brought about by full flap closure to those associated with normal tooth eruption (Crescini et at 1995). On the basis of their results, Vermette and co-workers question the indications for the continued usc of the apically repositioned flap method . A significant problem with the closed eru p- tion techniq ue is sometimes caused by a poor cho ice of bonded orthodon tic attachmen t. Since the midbuccal position of this tooth is easy to expose and to bond to, the orthodon- tist may be tempted to use a conventional orthodontic bracket in this instance (Wong- Lee and Wong, 1985). Becau se of the buccal prominence of the tooth, the lack of buccal bon e and the rela tive tightness of the replaced flap, damage may be caused to this muco- gingival tissue by the bulk of wide and high- profile conventional brackets (sec Fig. 4.4), which may lead to a breakdown of the over- lying tissue, to cause a dehiscen ce or even 'buttonholing' (Fig. 3.6). Once again, there- fore, the use of an eyelet offers significant advantages due to its more modest di men- sions and lower profile, at least until the tooth has erupted and been brou ght into close promixity to the labial arch wirc. 4 The relief of crowding to reduce canine displacement If the displacemen t of the canine has been due to crowding then it follows that spontan eous improvement of the position of the canine may well occur if the crowding is eliminated. Time may no t be on the side of the clinician opti ng for this approach, since the tooth may erupt through the oral mucosa if delay is incurred. Nevertheless, for the case in which this approach is to be used, a full case analy- sis is req uired, leading to a d iagnosis and treatment plan for the overall malocclusion. If the crowding is to be dispersed by distal movement of the molars, it will take it longer time before space is available in the canine region, wh ich is the most common area where this type of problem occurs. Considerable delay mu st be expected while the treatment is proceeding, before spontaneous improvement of the canine position ma y be seen. On the othe r hand, a premolar extraction will pro- vide immediate relief of the crowdi ng and an excellent opportunity for a self-correction of the buccal d isplacement and, with it, the disappearance of the poten tial periodontal hazard. PARTIAL AND FULL FLAP CLOSURE ON THE PALATAL SIDE Occasionally. impacted teeth that are located on the palatal side are palpable imm ediately beneath the palatal mucosa. The surgical removal of a circu lar section of the ove rlying mucosa (sec Fig. 6.26) to leave the tooth exposed is tempting and has obviou s advan- tages. However, the palatal mucosal covering is very thick and will leave a broad cut sur- face, which will tend to close over unless its edges are more radically trimmed back and the dental follicle removed . Thus, for a deeply placed tooth, the exposure will ad ditionally need to be maintained using a surgical pack. This type of surgical approach will therefore leave the tooth with a soft tissue deficiency and a long clinical crown at the completion of the orthodontic alignme nt.