Ankylosed Primary Molars, Andlaw (1974) Described Surface Defects from Bicuspids Preceded by Non-Ankylosed 11 Molars

PEDIATRICDENTISTRY/Copyright (~) 1980 The AmericanAcademy of Pedodontics/Vol. 2, No, 1

Ankylosedprimary mola.rs: Results and treatment recommendat,onsfrom an eight-year longitudinal study

Louise Brearley Messer,B.D.Sc., L.D.S., M.D.Sc. Jay T. Cline, D.D.S., M.A.

Abstract continues concomitantly with vertical alveolar bone growth,~,3 and the tooth is immobile to manual rock- A total of 263 ankyloscd primarymolars in 107 ing.4,5 children aged three to 12 years was studied for four years. Forty-six children remainedin the study for eight years. The etiology of the condition remains unknown. Extrinsic causative factors implicated are local me- Observationof affected dentitions showedthat the con- ~ ~ dition waslikely to recur. Threeclinical pa~ternsfor the chanical trauma, disturbed local metabolism, local- condition are described. Typically, maxillary molars be- ized infection, 6 chemical or thermal irritation 7 and came ankylosed earlier and demonstrated more severe tooth reimplantation, s Intrinsic factors cited include a in[raocclusion than mandibularmolars. Mandibularfirst genetic or congenital gap in the periodontal liga- molars usually remainedslightly or moderatelyin#a- ment. Since both erupting and exfoliating teeth show occluded; mandibularsecond molars and maxillary first alternating periods of resorption and deposition of and second molars showedprogressively severe infra- bone and cementum,° aberrant deposition of these tis- occlusion. Followingeither extraction or ex~oliation of the suesI° may produce an area of ankylosing tissue.Z, affected molars, the succedaneousbicuspids did not differ In a summaryof studies reporting the prevalence of in either coronal morphologyor in distribution of enamel ankylosed primary molars, Andlaw (1974) described surface defects from bicuspids preceded by non-ankylosed 11 molars. Mandibularfirst molars usually ex[oliated on a range from 1.3% to 38.5%. The differences were schedule; failure to employtimed extraction for severely attributed to ethnic factors, and also to differing diag- infraoccluded molars resulted in reduced alveolar bone nostic criteria. Amonghealthy Caucasian children of support [or the bicuspid. Treatment recommendations predominantly Scandinavian descent residing in the are developedbased .upon the molar type, clinical pattern, Minneapolis-St. Paul area of Minnesota, we reported and the severity of in#aocclusion. a prevalence of 6.9%.12 Contrary to studies reporting the mandibular second primary molar to be most frequently affected, 4,z3,1~ our studies and others have Introduction implicated the mandil3ular first primary molar most frequently. 1~,15,16 Multiple instances of ankylosis oc- Dental ankylosis may be defined as an anatomical cur as frequently as single instances, ~7 and a patient fusion of cementum with alveolar bone, occurring at 1 with one or two ankylosed teeth is likely to have other any time during the course of eruption. Occasionally, teeth become ankylosed later. 1°,1v Radiographically, the tooth may become ankylosed prior to emergence the zone of ankylosing tissue may not manifest as a into the oral cavity, or may ankylose during active localized obliteration of the periodontal ligament eruption before contact is made with the opposing space, since the zone may be only a microscopic re- dentition. 2 Clinically, the crown is located below the pair of cemental resorption by osteoid-like tissue con- occlusal plane, while the eruption of adiacent teeth tinuous~8-2° with the alveolar bone. The presence of ankylosed primary molar teeth Accepted: December3, 1979 may complicate the eruption and development of the PEDIATRIC DENTISTRY Vol. 2, No.1 37 permanent dentition. Typically, there is delayed ex- Purposes of Short-Term and Long-Term Studies zl foliation of affected teeth with subsequent compli- The purpose of the short-term study was to eluci- cations such as deflected eruption paths for adiacent date the characteristics of ankylosis of individual z or opposing teeth, impaction of succedaneous bicus- molars, ~vith respect to age at diagnosis, severity of 11 pids,% localized or generalized loss of needed arch infraocclusion, and distribution of the condition. 21 length, and tipping of adiacent teeth over the anky- Dentitions in the long-term study were used to losed primary molar or supraeruption of opposing study the sequelae of ankylosis with respect to over- ]~,2~,2z teeth. These sequelae may result in malocclu- retention of the primary molar, and the clinical and sion. radiographic appearance of the succeeding bicuspid In the past, the treatment of ankylosed primary in comparison with other bicuspids preceded by non- -° molars has been largely empirical. Luxation, restor- ankylosed primary molars in the same dentitions. ing the tooth to occlusion ~vith a variety of techniques and materials, -0~,°’3 and extraction,~,z°, zl have all been Diagnosis of Ankylosis utilized. While the literature contains many anecdotal The diagnosis was based upon two essential cri- reports of the relative success of these treatment ap- teria: proaches, clear documentation of indications, contra- (1.) The entire occlusal surface of the primary indications and possible sequelae is lacking. In order molar was located at least 1 mmbelow the to develop more rational bases for treatment, a two- expected occlusal plane as judged from the part clinical investigation comprising a short-term nearest adjacent non-ankylosed teeth in the (four-year) study and a long-term (eight-year) study same5 quadrant. was designed. A group of affected dentitions was fol- (2.) The molar was immobile when subiected man- lowed longitudinally with periodic examinations, ra- ually to a rocking movement,4 in contrast to diographs and study models, until complete erup- other (non-exfoliating) primary molars in the tion of all bicuspids, permanent cuspids, and perma- dentition. nent second molars. No attempt was made by the The emission of a sharp clear sound on percussion investigators to dictate treatment of the ankylosed was not an essential criterion because of its subiec- molars by the attending dentists in order that cur- tivity, a9 Radiographic evidence of bony union was rently-employed treatment regimes would be used un- not~z required because of its variability. hindered. Distribution of Primary Molars The short-term study group comprised 107 denti- Study Design tions (45 males; 62 females) which at first examination contained a total of 191 ankylosed molars (Table Study Population 1). The group included six sibships each containing A total of 107 healthy Caucasian children of pre- two affected children. Thirty-five dentitions each dominantly Scandinavian descent, ranging in age from contained a single ankylosed molar and 72 dentitions three to 12 years and possessing one or more anky- each showed two or more affected molars. The 107 losed primary molars, was studied in the Pediatric ¯ dentitions were studied for four years, during which Dentistry Clinic of the University of Minnesota time 31 dentitions (29~) showed a recurrence School of Dentistry. Using periodic clinical and radio- ankylosis involving a further 72 primary molars (Ta- graphic observations, the history of each ankylosed ble 1 ). primary molar (test molar), and non-ankylosed pri- Thereafter, the long-term study group contained 46 mary molar in each dentition was followed and ob- dentitions (23 males; 23 females; three sibships each servations recorded on these teeth and their succeed- with two affected children) totalling 116 ankylosed ing bicuspids. molars (Table 1).~ These were followed for eight The majority of children received their dental care years. No additional diagnoses were made during throughout the study at the clinics of the University the second four years of the study. For this group, of Minnesota School of Dentistry; the remainder at- the bicuspids preceded by non-ankylosed primary tended private dentists for regular dental care. In all molars in the same dentitions were pooled as a com- instances, the ankylosed molar either was ob.served parison group. These teeth were distributed as fol- periodically, or extracted and appropriate space lows: mandibular first: 9.8; mandibular second: 48 (a maintenance instituted. No tooth was treated by lux- further three teeth were congenitally absent); maxil- ation; only ankylosed teeth with congenitally-missing lary first: 86; and maxillary second: 86 (a further two bicuspids ’were restored’ to occlusion with stainless teeth were congenitally missing). Since many of the steel crowns. dentitions had contralateral molars affected with

ANKYLOSEDPRIMARY MOLARS 38 Messerand Cllne Table 1. Distribution of ankylosedprimary molars in i07 affected dentitions (short- and long-termstudies)

Time of No. Ankylosed Primary Molars Study diagnosis Md 1st Md 2nd Mx 1st Mx 2nd Total Short term at first exam 131 37 16 7 191 at later exam 18 40 5 9 72

Total 149 77 21 16 263 Long term at first or later exam 64 41 7 4 116 ankylosis, teeth could not be pair-matched for com- aminedin order to identify distribution characteristics parisons. Therefore, the findings for each group of for the condition. ankylosed molars were compared with those for the corresponding group of pooled non-ankylosed molars. Data Collected in Long-TermStudy Data Collected in Short-Term Study Overretention of Ankylosed Primary Molars A molar was deemed overretained if it was still in Age at Diagnosis of Primary Molar Ankylosis position, and immobile, after the contralateral non- The age of each child at the time of diagnosis of ankylosed primary molar had exfoliated. An ankylosed each ankylosed molar was recorded, based on clinical molar which became mobile close to the expected ex- observations and from existing clinical and radio- foliation time was not considered overretained. In in- graphic records maintained by the clinic before com- stances of ankylosis of a contralateral pair of molars, z4 mencement of the study. reference was made to tables of chronology, in con- iunction with an examination of the eruption se- Extent of Infraocclusion quence for the particular dentition and the status of Using study models, the extent of infraocclusion of root development of the succedaneous bicuspids. each ankylosed molar was classified at diagnosis as Clinical, Radiographic, Occlusal and one of the following: Periodontal Observations on Bicuspids Slight: The entire occlusal surface was lo- When all bicuspids, permanent cuspids and perma- cated approximately 1 mmbelow the nent second molars were fully erupted, each bicuspid expected occlusal plane as iudged was air-dried and examined clinically using a mirror from the two nearest non-ankylosed and explorer* for the following: coronal and radicular teeth in the same quadrant. morphology, hypoplasia and hypomineralization, coronal position, and rotation. The periodontal tissues Moderate: The entire occlusal surface was lo- were examined clinically and radiographically for evi- cated with both marginal ridges ap- dence of pocket-formation, lamina dura thickening, proximately level with, or iust cervi- and alveolar bone loss. Observations were made in- cal to, the contact area of one or both dependently by both authors, each unaware of adiacent tooth surfaces. In instances whether the bicuspid was preceded by an ankylosed of ankylosis of two adiacent primary or non-ankylosed molar. Positive findings were re- molars, the contact area of the first corded only when there was unanimity between ex- secondary molar was used for refer- aminers using the following criteria: ence. Coronal and radicular morphology: Severe: The entire occlusal surface was lo- The morphological features of contralateral teeth cated level with or below the inter- were compared with each other and with those de- proximal gingival tissue of one or scribed by Wheeler (1974), ~-5 and any marked dif- both adiacent tooth surfaces. ferences recorded. Distribution Characteristics of Ankylosis * No. 5DEexplorer, Hu Friedy Manufacturing Co., Chi- Sequential study models for each child were ex- cago,Illinois ’ 60618.

PEDIATRICDENTISTRY Vol. 2, No.I 39 Table 2. Extent of infraocclusion of 263 ankylosedprimary molars at initial diagnosis(short-term study)

NO. Ankylosed Molars (%) Infraocclusion Md 1st Md 2rid Mx 1st Mx 2nd Total Slight 111 (75) 36 (47) 9 (43) 6 (37) 162 Moderate 36 (24) 32 (41) 10 (48) 7 (44) 85 Severe 2 (1) 9 (12) 2 (9) 3 (19) 16 Total 149 77 21 16 263

Hypoplasia: the mesial and distal contact areas using a perio- Non-hereditary hypoplasia was defined after Sicher dontal probe.* (1962) 26 as localized, circumscribed pitting, fur- Thickening of lamina dura: rowing or absence of enamel which may or may not be associated also with hypomineralization. Thickening of the lamina dura was diagnosed from intraoral radiographs based on the description of H ypomineralization : Goldmanand Cohen ( 1973 ).~8 Non-fluorotic surface enamel defects of hypominer- Alveolar bone loss: alization were asymmetrical round or oval lesions clearly differentiated from adiacent normal enamel Vertical and horizontal bone loss was diagnosed from intraoral radiographs, based on the descrip- and often creamy yellow or brown in color on nor- tionz8 of Goldman and Cohen (1973). mally contoured enamel surfaces, z7 Very mild fluorosis was defined after Russell (1961) 27 as A comparison of the binomial distributions ~9 was symmetrical small spots or minute, lacy, horizontal used to test for any statistically significant difference lines generally following the incremental lines of between the distributions of observations for bicus- enamel development and imperceptibly demar- pids preceded by anl~ylosed and non-ankylosed mo- cated from normal enamel and of a "paper white" lars. color. The cusp tips may have a frosted appearance and the condition usually affects the incisal or oc- Results of Short-Term Study clusal half, or more, of contralateral teeth. The enamel is smooth to an explorer. Age at Diagnosis of Primary Molar Ankylosis Coronal malposition: The mean ages at diagnosis were as follows: man- A bicuspid was deemed malpositioned if the en- dibular first molar: 7.1 (range 5.2 - 9.2 yrs.); man- tire crown was placed buccally, lingually or in in- dibular second molar: 8.0 (range 5.1 - 10.4 yrs.); fraocclusion from the expected position of that maxillary first molar: 6.2 (range 4.7 - 8.6 yrs.); max- tooth in the dental arch contour. illary second molar: 4.6 (range 3.0 - 9.4 yrs.). The diagnosis of ankylosis of the maxillary first molars Coronal rotation: frequently coincided with the eruption of the maxil- This was classified as none, slight, moderate or se- lary first permanent molar, For several of the maxil- vere, based upon the extent of deviation of the lary second molars in the study, the apparent failure tooth from its expected angulation between the two adiacent teeth, iudging on the positioning of the of complete eruption of this tooth was the reason for the patient presenting to the clinic. For all other mesial marginal ridge. A bicuspid was deemed ankylosed molars, the parents were unaware of the slightly rotated if the position of this ridge was de- viated, but less than 20°, to either the buecal or condition until it was brought to their attention. lingual of its expected position between the ad- Extent of Infraocclusion iacent teeth. If the mesial marginal ridge was devi- Most maxillary first and second primary molars ated by more than 20°, but less than 90°, to either were in moderate or severe infraocclusion when diag- the buccal or lingual, the bicuspid was deemed nosed (Table 2). These teeth tended to show a rela- moderately rotated; a bicuspid rotated 90° or more tively rapid progression toward more severe infraoc- from its expected position was deemed severely rotated. clusion. Mandibular first molars were only slightly

Periodontal pocket formation: * No. 0 periodontal probe, HuFriedy ManufacturingCo., Periodontal pocket depth was measured beneath Chicago,Illinois 60618. ANKYLOSEDPRIMARY MOLARS 40 Messerand Cline Table 3. Three clinical patterns of primary molar ankylosis in 107 dentitions diagnosed over four-year observation period (short-term study)

Total Ankylosis Pattern Arch Distribution (no. dentitions) dentitions (%)

I Molar Pair Mand 1 contralateral pair (29) 48 (45%) 2 contralateral pairs (15) 1 adjacent pair (2) Max 1 contralateral pair (2)

II Single Molar Mand 1st molar (24) 35 (33%) 2nd molar (6) Max 1st molar (4) 2nd molar (1)

III Multiple Molars Mand 3 teeth — 1 pair plus 1 single (8) 24 (22%) and 4 teeth — 1 pair plus 2 singles (5) Max 5 teeth — 2 pairs plus 1 single (9) 6 teeth —3 pairs (1) 7 teeth — 3 pairs plus 1 single (1) affected (Table 2) and rarely became more severely infraoccluded, whereas most mandibular second molars showed a progressive development of more severe infraocclusion. No molar which became ankylosed late in the development of the succedaneous bicuspid became severely involved and these usually remained in slight or moderate infraocclusion. Figure 1 shows the intraoral radiographs of one patient over a 55-month period. This patient illus- trates several salient features of molar ankylosis. The first radiographs (Figure IA) show slight infraocclusion of the mandibular left and right first primary molars. Interproximal lesions in these teeth were restored with amalgam (one tooth also later received a stainless steel crown) and both teeth later exfoliated on schedule. Meanwhile, the mandibular left and mandibular right second primary molars became moderately ankylosed (Figure IB), as did the maxillary left second primary molar (perhaps following the ectopic eruption of the adjacent first permanent molar). The maxillary second primary molar was extracted and a space maintainer placed; the mandibular sec- Figure 1. A series of bitewing radiographs of a Cau- ond molars exfoliated on schedule. A root fragment casian female showing progression of primary molar of the mandibular right second primary molar re- ankylosis. (A) Note slight infraocclusion of mandibular mained (Figure 1C), probably related to the unequal first primary molars and ectopic eruption of the maxil- resorption pattern of the mesial and distal roots. lary left first permanent molar. (B) Note loosening of mandibular first primary molars, moderate infraocclu- Distribution Characteristics of Ankylosis sion of the mandibular second primary molars with an unequal resorption pattern of the roots of the man- Three clinical patterns for the condition were ap- dibular right second primary molar, and moderate in- parent (Table 3). The most frequently occurring was fraocclusion of the maxillary left second primary Pattern I (48 dentitions, or 45%) where one or more molar. (C) All bicuspids are fully erupted. Note the contralateral molar pairs, or an adjacent pair of mo- residual primary molar root fragment mesial to the lars, were ankylosed. A single molar, Pattern II, was mandibular right second bicuspid.

PEDIATRIC DENTISTRY Vol. 2, No. 1 41 affected in 35 dentitions (3370). Pattern III com- Occlusal Observation on Bicuspids prised multiple ankylosed molars ranging from three The occlusal observations for test bicuspids are to seven affected teeth (24 dentitions, or 2270). This shown in Table 5. Amongmandibular first bicuspids, pattern was viewed as a combination of one, two, or four test teeth (670) and three unaffected bicuspids three molar pairs (as Pattern I), plus one or more (1170) were in infraocclusion; the difference was not single occurrences in any quadrant. statistically significant. Inadequate mesiodistal space was present for 35 test mandibular first bicuspids Results of Long-TermStudy (55g) and for 15 unaffected mandibular first bicuspids (54g). This difference was not statistically sig- Overretention of Ankylosed Primary Molars nificant. A total of 58 (90.6%) test mandibular first The treatment histories are summarized in Table 4. bicuspids showed coronal rotation (slight: 41 teeth, Most mandibular first molars exfoliated on schedule, moderate: 17 teeth, severe: none); among unaffected and none left residual root fragments. Mandibular bicuspids, only three (11~;) were rotated. Statistically, second molars were less prone to exfoliation; residual test mandibular first bicuspids were significantly root fragments were shown by two molars that ex- more frequently rotated than unaffected mandibular foliated and by four molars that were extracted ahead first bicuspids (Z=7.4672; p<0.01). of exfoliation. None of the 11 maxillary molars that Among test mandibular second bicuspids, four were extracted early left root fragments. Five mandib- teeth (llg) were in infraocclusion. This distribution ular second molars without permanent successors did not differ significantly from that of unaffected were restored with stainless steel crowns. During the mandibular second bicuspids (four teeth or 8g were observation period, these teeth became severely infra- in infraocclusion). Eleven test mandibular second bi- occluded and radiographically showed extensive re- cuspids (30g) and four unaffected bicuspids (8~;) placement of the periodontal ligament with mineral- showed inadequate mesiodistal space. This difference ized tissue. Periodic replacement of the crowns was ~vas statistically significant (Z=2.6327, p<0.01). The required to maintain occlusion. Eventually, orthodon- distribution of rotated mandibular second bicuspids tic treatment was instituted for one child and the in the test group (21 rotated or 58g) did not differ tooth was extracted surgically. significantly from that of the unaffected group (29 rotated or 60~o). Clinical and Radiographic Appearance None of the eleven test maxillary bicuspids were of Bicuspids infraoccluded; one showed mesiodistal space inade- Table 5 summarizes the clinical and radiographic quacy and four teeth were rotated. These sample sizes appearance of the test bicuspids. were deemed too small for statistical comparison with Amongtest mandibular bicuspids, hypoplasia and/ unaffected maxillary bicuspids. or hypomineralization defects were seen in 25 of the Periodontal Observations on Bicuspids 64 (39~) first bicuspids and in eight of the 36 (22g) second bicuspids. In all instances, similar multiple The periodontal observations on the test bicuspids enamel surface defects were seen in other bicuspids in are shown in Table 5. Amongthe 64 test mandibular the same dentition, and in no instance could the de- first bicuspids, none of those preceded by first pri- fects be clearly attributed to ankylosis of the pre- mary molars exfoliating on schedule showed any un- ceding primary molar or to the treatment procedure usual findings. Of the 11 in the extraction group, the (observation until exfoliation, or extraction) that had t~vo bicuspids preceded by overretained mandibular been followed. Very mild fluorosis was seen in 40g first molars both showed periodontal pocketing (3-4 of the 46 dentitions studied. mm), thickening of the lamina dura and inadequate On radiographic examination, four test bicuspids vertical alveolar bone height. The latter two observa- showed "V"-shaped notching of the root outline, lo- tions were also recorded for one mandibular first bi- cated in the middle one-third. In three instances, the cuspid preceded by a primary molar which was ex- preceding primary molar had been overretained and tracted early. Nbne of the unaffected mandibular first ex-tracted. Of bicuspids preceded by non-ankylosed bicuspids showed these periodontal findings. molars, none showed "V" root notching. The distri- Amongthe 16 test mandibular second bicuspids in bution of apical root flexion did not differ signifi- the exfoliation group, one bicuspid .showed pocket cantly between bicuspids preceded by ankylosed or formation (3-4 mm)and this tooth, plus a second bi- non-ankylosed primary molars. cuspid in the same group, showed inadequate vertical alveolar bone height. Reduced alveolar bone height was ~Iso shown by a further three bicuspids in the

ANKYLOSEDPRIMARY MOLARS 42 Messerand Cline Table 4. Treatmenthistory for 116 ankylosedmolars in 46 affected dentitions (long-termstudy)

NO. Ankylosed Primary Molars (%) Treatment History Md 1st Md 2nd Mx 1st Mx 2nd Total

Exfoliated on schedule 53 (83) 16 (39) 0 0 69 Extracted before exfoliation time 9 (14) 15 (37) 7 (100) 4 (100) 35 Overretained and extracted 2 (3) 5 (12) 0 0 7 Occlusion restored with steel crown* 0 5 (12) 0 0 5

Total 64 41 7 4 116

* Five mandibular secondbicuspids were congenitally missing.

Table 5. Coronal, radicular and periodontal observationson 111" bicuspids precededby ankylosedprimary molarsin 46 affected dentitions (long-term study)

No. Affirmative Observationson Bicuspids Mand 1st Mand 2nd Mx 1st Mx 2rid Extoliatedt Extractedtt Exloliated Extracted Extracted Extracted Total Observation (n=53) (n=11) (n=16) (n=20) (n~-7) (n=4)

Crown hypoplasia 2 1 0 1 0 0 4 hypomineralization 17 5 5 2 0 0 29

Root "v" notching 1 1 0 2 0 0 4 apical flexion 8 2 1 2 1 0 14

Occlusion infraocclusion 2 2 2 2 0 0 8 m-d space inadequate 30 5 4 7 1 0 47 rotation 47 11 13 8 3 1 83

Periodontal pocket formation 0 2 1 1 1 0 5 lamina dura thickened 0 3 0 0 1 0 4 alveolar boneloss 0 3 2 4 1 0 10

* Only 111 of the 116 teeth are shownsince five mandibular secondbicuspids were congenitally absent. t Preceding primary molar exfoliated on schedule. 11 Precedingprimary molar extracted either before exfoliation time or following overretention.

PEDIATRICDENTISTRY Vol.2, No.! 43 late extraction group. None of the unaffected man- subsequent to ankylosis of the mandibular second dibular second bicuspids showed similar periodontal molar in the same dentition, but there was a high in- findings. Of the eleven test maxillary bicuspids, peri- cidence of ankylosis of the latter tooth subsequent to odontal pathology was seen for one maxillary first involvement of the former. Owent has observed that bicuspid. The periodontal pocket depth was 3-4 mm. ankylosis of maxillary molars usually occurs coinci- None of the unaffected maxillary bicuspids showed dent with involvement of opposing mandibular mo- periodontal pocket formation, lamina dura thickening lars, and this is supported by the present observations or alveolar bone discrepancy. where 30 of the 37 ankylosed maxillary molars were present in dentitions which also showed mandibular Discussion involvement. However, it is not an invariable finding as there were seven instances of affected maxillary Characteristics of AnkylosedMolars molars where no mandibular molar was involved As shown previously,12,1~ the mandibular first pri- either initially, or on longitudinal study. mary molar was the tooth most frequently affected by The present study indicates that individual molars ankylosis in the present study. Since this tooth usually tend to show a somewhat typical pattern of severity. shows only slight and rarely moderate infraocclusion, In comparison with mandibular molars, maxillary mo- and typically exfoliates on schedule, the diagnosis of lars tend to show severe, early involvement and the ankylosis may be missed. Consequently, it is not sur- relative severity maybe partially reflecting a spurt of prising that the mandibular second molar, which is alveolar bone growth coincident with the eruption of usually in more severe infraocclusion, has been con- the maxillary first permanent molars. The relative sidered to be the tooth most frequently affected by slightness of the typical infraocclusion of the affected ankylosis.4,13,14 In the present study, maxillary molars mandibular first primary molar may reflect, in part, were affected less frequently than mandibular molars, a lessened increment in vertical alveolar bone growth and the maxillary second molar least of all, confirm- occurring in the cuspid-first molar region prior to the ing the observations of many other surveys on this exfoliation time of the first primary molar. aspect4,1"~-1 of5 ankylosis. The decided tendencies seen toward multiple oc- The present study appears to be one of very few currences, contralaterally affected teeth, and lack of examining~5,~6 the time of diagnosis .of ankylosis. predilection for the side of the arch first affected, Since a criterion for inclusion of the dentition in the confirm previous studies.4,14, ~9 In the present study, study was the presence of at least one tooth already only 35 of the 107 dentitions (33~g) in the four-year ankylosed, the actual onset of the condition for these study showed ankylosis limited to a single molar, and teeth cannot be determined. Also, the diagnostic cri- the remaining 72 dentitions (67~o) each contained two teria are applicable only after the tooth has begun or more ankylosed molars totaling 228 affected teeth. to manifest the condition clinically, and presumably The teeth were distributed in three distinct clinical the cellular changes occur considerably in advance of patterns which serve to indicate where a contralateral the clinical picture. Nevertheless, the approx.imations occurrence of the condition is likely to occur, and made in the present study serve to show that the provide a basis for treatment recommendations, as four different primary molars are prone to ankylose described below. Contralateral occurrences are more at various times and that these are usually quite typi- likely in the mandibular arch than in the maxillary, cal for each molar. and single occurrences are more likely to occur in Maxillary primary molars tended to ankylose early, the maxillary than in the mandibular arch. either before the eruption of the maxillary first permanent molar (as was shown by most of the second Characteristics of Succeflaneous Bicuspids primary molars studied) or at approximately the The present study indicates that the presence of a same time as the maxillary first permanent molar preceding ankylosed primary molar is not likely to erupted (as seen for most of the maxillary first pri- affect coronal morphologyor to initiate coronal hypo- mary molars studied). Mandibular primary molars plasia and/or hypomineralization of the succeeding tended to ankylose later than maxillary molars, the bicuspid. This lends support to the opinion of Kollar mean age of diagnosis for mandibular first molars be- (1972) 3° that the morphological template of the ing 7.1 years and 8.0 years for mandibular second crown is established very early in embryological de- molars. The majority of the mandibular first molars velopment and is not readily altered. For the maiority became ankylosed soon after the eruption of the first of the ankylosed teeth studied in the present report, permanent molar in the same quadrant, but this was the crowns of the succedaneous bicuspids were al- unusual among mandibular second molars. Ankylosis ready fully formed at the time described as the first of mandibular first molars did not appear to occur clinical diagnosis of the condition. Presumably the

ANKYLOSEDPRIMARY MOLARS 44 Messerand Cl|ne cellular changes involved in the process of ankylosis Prognosis and Treatment Recommendations had no effect on the coronal tissues of the forming The present investigation did not seek to evaluate succedaneous tooth. The lack of an increased preva- comparatively the efficacy of several treatment re- lence of enamel surface defects in the succeeding gimens for ankylosed molars. Instead, the study sought bicuspids is in contrast to the findings of Rule, to observe the consequences of the three treatment Zacherl and Pfefferle (1972). 31 In a sample of 262 approaches (observation; extraction; restoration to oc- bicuspids succeeding ankylosed primary molars, these clusion) utilized by the attending dentists. The lit- workers described a statistically significant increase erature reveals widely divergent opinions on the treat- in the number of enamel surface defects over those ment of ankylosed primary molars. Hovell (1966)z~ seen in control bicuspids and speculated on a corre- stated that most cases require no treatment other than lation between ankylosis and the coronal abnormali- observation, while others recommendsurgical extrac- ties. The present study examined a larger sample of tion as the usual treatment on the basis that ankylosed children with ankylosed teeth, and also identified teeth neither exfoliate nor allow the eruption of the that 40~ of the dentitions demonstrated very mild succeeding permanent teeth.9, z4-3~ Andlaw11 (1974) fluorosis. This could have masked additional enamel has developed a more conservative series of treatment defects of a non-fluorotic origin. recommendations based upon the extent of infraoc- No clear association was found in the present study clusion of the affected tooth. The present study adds between apical flexion of the roots of succeeding bi- to those recommendations by taking into considera- cuspids and "V"-shaped notches in the root periphe- tion also the three clinical patterns of ankylosis de- ries, and ankylosis of the preceding molars. Notching scribed and the recognized ankylosis characteristics of the root outline on a radiograph is an equivocal for each type of primary molar. finding since the appearance of the root outline is The findings of the present study suggest that the largely dependent upon the radiographic technique maiority of ankylosed mandibular first primary molars employed. These observations support the conclusion can be expected to become involved after the erup- of Steigman, Koyoumdiisky-Kaye and Matrai (1974), tion of the mandibular first permanent molar, and that ankylosed teeth usually have no causative influ- that the condition is likely to becomebilateral. Anky- ence2 on the rate of development of their successorsP losis of other primary molars in the dentition is likely, Examination of the occlusion of the succedaneous especially of the mandibular second primary molars. bicuspids suggests that those preceded by an anky- The first primary molar is likely to demonstrate only losed primary molar are more likely to demonstrate slight, progressing but occasionally to moderate, infra- inadequate mesiodistal space and to show coronal ro- occlusion and can be expected to loosen and exfoliate tation. Although these differences were demonstrated on schedule. This expectation confirms the observa- to be significant statistically, it cannot be concluded tions of Steigman et al. 1~ on the ankylosis characteris- to be more than a trend since the entire occlusion of tics of the .mandibular first primary molar. For these the affected dentitions was not evaluated. In addition, teeth, it is assumed that during the normal process of the bicuspids used for comparison were located in exfoliation, the ankylosing tissue is resorbed, allowing the same dentitions which showed ankylosed teeth, the tooth to becomemobile and exfoliate. ]° Rarely is thereby introducing a bias into the statistical treat- extraction or exfoliation of this tooth followed by ment of the data. residual root fragments. Therefore, the clinician is Bicuspids succeeding ankylosed primary molars ap- recommended to monitor dentitions with ankylosed pear more likely to exhibit periodontal pathology mandibular first molars by employing study models (and particularly if the molar was overretained or and space measurements, and to extract these teeth required extraction) than bicuspids succeeding non- only if they are severely infraoccluded and space loss ankylosed molars. The lack of vertical alveolar bone is imminent. If supraeruption of opposing teeth ap- height coupled with periodontal pocket formation is pears imminent, restoration of the occlusal surface to thought to be due to a failure of alveolar bone devel- full vertical dimension could be considered. opment which normally occurs with exfoliation of the The ankylosed mandibular second primary molar primary tooth and eruption of the permanent tooth. is likely to be affected bilaterally, and onset is likely An ankylosed primary molar is retained at its vertical to occur later than that of the mandibular first pri- position by the ankylosin~ tissue while adjacent teeth mary molar. With time, mandibular second molars continue to moveocclusally with appositional alveolar tend to become progressively more severely infraoc- bone growth. The impedance of primary tooth move- cluded than mandibular first molars. Mesial tipping ment serves to restrict vertical alveolar bone deposi- of the adiacent first permanent molar over the occlu- tion, hence there may be a reduced amount of bone sal surface of the affected tooth may occur, resulting surrounding the bicuspid. in loss of arch length. Failure to monitor these teeth

PEDIATRICDENTISTRY Vol. 2, No.1 45 can result in overretention of the molar and a local- severe infraocclusion, with an onset which may pre- ized lack of vertical alveolar bone. Ankylosed mandib- cede the eruption of the adjacent first permanent ular second molars should be kept under close obser- molar. Maxillary first primary molars also tend to in- vation with study mo~tels and arch length measure- creasingly severe infraocclusion and the onset may ments. Extraction should be performed if the tooth occur close to the time of eruption of the first perma- becomes moderately infraoccluded and/or mesial tip- nent molar. Additional ankylosed molars in the man- ping of the mandibular first permanent molar is im- dibular arch are likely to follow. The obvious severity minent, or if the molar fails to exfoliate on schedule for of the ankylosis of the maxillary primary molars in the that dentition. A passive lower lingual arch is a useful present long-term study clearly indicated the need for space maintainer in the former situation. Following early extraction. It is likely that failure to extract either extraction or exfoliation of the mandibular sec- these teeth would have resulted in tipping of adja- ond molar, the area should be examined closely for cent non-ankylosed teeth and consequent loss of arch root fragments as these may occur following the typi- length and inadequate vertical alveolar bone growth cally uneven resorption of the mesial and distal roots. leading to compromised periodontal support for the Restoration of singly affected mandibular molars succeeding bicuspids. Regardless of the severity of showing only slight infraocclusion with built-up res- the infraocclusion, it is recommendedthat ankylosed torations or stainless steel crowns appears to be a and immobile maxillary molars be extracted as early useful interim treatment during the mixed dentition as appears feasible. Since such extractions frequently period. There must be a permanent successor present require a surgical removal of the tooth on a child and both the vertical and mesiodistal dimensions of aged seven years or under, appropriate consideration the crown of the ankylosed tooth need to be main- should be given to the behavior management of the tained adequately. Active vertical alveolar bone child. In our experience, a distal shoe space main- growth related to the adjacent unaffected teeth is tainer is a useful appliance in the situation where an likely to necessitate the periodic replacement of the ankylosed maxillary second primary molar requires restoration. If however, the primary molar is in mod- extraction prior to the eruption of the adjacent first erate or severe infraocclusion, the vertical alveolar permanent molar. bone growth may be hindered and lead to a poor It is recommendedthat the treatment of dentitions periodontal prognosis for the succeeding bicuspid. with multiple ankylosed teeth be treated by employ- For such teeth, extraction and appropriate space ing a combination of the approaches recommended maintenance is recommended. above for individual molars. Siblings in the family In instances where the primary molar is ankylosed should also be monitored, since a familial tendency and the permanent molar is congenitally absent, early for5,1~ the condition has been reported. orthodontic and prosthodontic consultations should be Acknowledgments sought concerning the long-term treatment of the dentition. While the vertical and mesiodistal dimensions The assistance of Drs. David McKibbenand John Hinding of the ankylosed molar can be maintained with resin the initial clinical phasesof this studyis gratefldly, acknowl- edged. This study ~vas supported in part by a BiomedicalRe- torations throughout the mixed dentition, such res- search Support Grant from the National Institutes of Health. torations can only be considered of interim nature. Also, after the permanent dentition is established, the steady remodelling throughout life of alveolar bone supporting adjacent teeth is likely to require periodic References replacement of such built-up restorations. Biederman -0 1. Owen,T. L.: "Ankylosis of Teeth," J Mich State Dent (1968) has observed that because of cessation of Assoc, 47:347-350,1965. alveolar bone growth in the immediate area of the 2. Biederman, W.: "The Problem of the AnkylosedTooth," ankylosed tooth, the roots of adjacent teeth may be- Dent Clin North Am, July, 409-424, 1968. come denuded of bone and the tooth lost. Such long- 3. Darling, A. I. and Levers, B. G. H.: "SubmergedHuman term restorative and periodontal consequences sug- Deciduous Molars and Ankylosis," Arch Oral Biol, 18: 1021-2040,1973. gest that early consideration be given to extraction of 4. Biederman,W.: "Etiology and Treatment of Tooth Anky- the ankylosed tooth and space closure instituted in losis," Am] Orthod, 48:670-684, 1962. conjunction with orthodontic treatment of the denti- 5. Via, W. F.: "Submer~edDeciduous Molars: Familial tion. Tendencies," ] AmDent Assoc,-69:127-129,1964. The findings of the present study suggest similar 6. Adamson, K. T.: "The Problem of Impacted Teeth in Orthodontics," Aust ] Dent, 56:74-84, 1952. approaches to treatment for both maxillary first and 7. Atrizadeh, F., Kennedy,J., and Zander, H.: "Ankylosisof second primary molars. Maxillary second primary mo- Teeth FollowingThermal Injury," I PeriodontRes, 6:159- lars tend to show a relatively fast progression towards 167, 1971.

ANKYLOSEDPRIMARY MOLARS 46 Messerand Cline 8. Finn, S. B.: Clinical Pedodontics, 4th Ed., Philadelphia: the Age of Fifteen Years," I Am Dent Assoc, 20:397-427, W. B. Saunders Co., 1973, p. 259. 1933. 9. Boyle, P. E., ed.: Histopathology of the Teeth and Their 25. Wheeler, R. C.: Dental Anatomy, Physiology and Occlu- Surrounding Structures, 4th Ed., Philadelphia: Lea and sion, 5th Ed., Philadelphia: W. B. Saunders Co., 1974, Febiger, 1955, p. 276. pp. 195-236. 10. Henderson, H. Z.: "Ankylosis of Primary Molars: A Clin- 26. Sicher, H., ed.: Orban’s Oral Histology and Embryology, ical, Radiographic, and Histologie Study," J Dent Child, 5th Ed., St. Louis: C. V. MosbyCo., 1962, pp. 100-102. 46:117-122, 1979. 27. Russell, W. L.: "The Differential Diagnosis of Fluoride 11. Andlaw, R. J.: "Submerged Deciduous Molars: A Review, and Nonfluoride Enamel Opacities," I Public Health Dent, With Special Reference to the Rationale of Treatment," 21:143-146, 1961. Int Assoc Dent Child, 5:59-66, 1974. 28. Goldman, H. M. and Cohen, D. W., eds.: Periodontal 12. Brearley, L. J. and McKibben,D. H.: "Ankylosis of Pri- Therapy, 5th Ed., St. Louis: C. V. MosbyCo., 1973, pp. mary Molar Teeth, I Prevalence and Characteristics; II 319-321. Longitudinal Study," I Dent Child, 40:54-63, 1973. 29. Freund, J. E.: Modern Elementary Statistics, New York, 13. Dixon, D. A.: "Observations on Submerged Deciduous Prentice-Hall, 1952, pp. 198-219. Molars," Dent Pract Dent Rec, 13:303-316, 1963. 30. Kollar, E. J.: "Histogenetic Aspects of Dermal-Epidermal 14. Lamb, K. A. and Reed, M. W.: "Measurement of Space Interactions," in Slavkin, H. C., and Baretta, L. A., eds: Loss Resulting From Tooth Ankylosis,’" J Dent Child, 35: Developmental Aspects of Oral Biology, NewYork: Aca- 483-486, 1968. demic Press, 1972, pp. 125-149. 15. Steigman, S., Koyoumdiisky-Kaye, E., and Matrai, Y.: 31. Rule, J. T., Zacherl, W. A., and Pfefferle, A. M.: "The "Subnaerged Deciduous Molars in Preschool Children: An Relationship Between Ankylosed Primary Molars and Mul- Epidemiologic Survey," ] Dent Res, 52:322-326, 1973. tiple Enamel Defects," ] Dent Child, 39:29-35, 1972. 16. Krakowiak, F. J.: "Ankylosed Primary Molars," I Dent 32. Steigman, S., Koyoumdjisky-Kaye, E., and Matrai, Y.: Child, 45:288-292, 1978. "Relationship of Submerged Deciduous Molars to Root 17. Brearley, L. J. and McKibben, D. H.: "A Longitudinal Resorption and Development of Permanent Successors," Study of Ankylosed Primary Molar Teeth," IADR Abstr, J Dent Res, 53:88-93, 1974. No. 678, 1972. 33. Hovell, J. H.: In Walther, D. P. ed.: Current Orthodontics, 18. Noyes, F. B.: "Submerging Deciduous Molars," Ang/e Bristol: Wright, 1966, p. 203. Orthod, 2:77-87, 1932. 34. ShaIer, W. G., Hine, M. K., and Levy, B. M.: A Textbook 19. Thornton, M. and Zimmermann, E. R.: "Ankylosis of of Oral Pathology, 3rd Ed., Philadelphia: W. B. Saunders Primary Teeth," I Dent Child, 31:120-126, 1964. Co., 1974, p. 66. 20. Eichenbattm, I. W.: "Tooth Eruption and Ankylosis," 35. Schour, I. and Massler, M.: In Brauer, J. C.: Dentistry ]Prev Dent, 4:39-45, 1977. ~or Children, NewYork: McGraw-Hill, 1964, p. 117. 21. Konstat, M. M. and White, G. W.: "Ankylosed Teeth: A Review of the Literature," J Mass Dent Soc, 24:74-78, 1975. 22. Gorelick, L. and Geiger, A. M.: "Direct Bonding in the DRS. MESSER and CLINE are affiliated with the Management of an Ankylosed Second Deciduous Molar," Department of Pediatric Dentistry, University of I Am Dent Assoc, 95:307-309, 1977. 23. Bonin, M.: "Simplified and Rapid Treatment of Ankylosed Minnesota, Minneapolis, Minnesota. Primary Molars With an Amalgamand Composite Resin," Requests for reprints may be sent to Dr, Louise ] Dent Child, 43:159-162, 1976. 24. Logan, W. H. G. and Kronfeld, R.: "Development of tho Brearley Messer, Department of Pediatric Dentistry, HumanJaxvs and Surrounding Structures From Birth to University of Minnesota, Minneapolis, MN55455.

PEDIATRIC DENTISTRY Voh2, No. 1 47