Unilateral delayed eruption of maxillary permanent first molars: four case reports MiekoTomizawa.DDS.PhD Hiroko Yonemochi, DDS MisakoKohno.DDS.PhD Tadashi Hoda, DDS, PhD

elayed eruption or impaction of permanent and 6 years 7 months ± 8 months for Japanese girls. Fen- teeth is one of the severe problems that can estration of the gingiva was performed surgically in each Doccur during the mixed dentition period. patient and occlusal guidance by traction was used for These conditions can occur in any permanent tooth, one. This paper presents the clinical and histopathologi- but the incidence of delayed eruption of the perma- cal findings in these four cases of unilateral delayed erup- nent first molars, especially maxillary permanent first tion of maxillary permanent first molars. molars, is very low. Johnsen1 found only one case of delayed emergence of a maxillary first as a re- Case reports sult of local etiologic factors in a review of the records Casel of 1032 young people ranging in age from 8 to 18 A 7-year, 11-month-old Japanese girl visited years. Dachi and HowelP examined 1685 sets of ra- our clinic with the complaint of unerupted maxil- diographs at the University of Oregon and found no lary right permanent first molar. The maxillary case of impacted permanent first molars. Grover and 3 left permanent first molar had erupted at the age of 6 Lorton found only one case of an unerupted maxil- years, 4 months. Intraoral examination revealed no lary first molar in their survey of the panoramic ra- swelling or redness of the gingiva in the region of the diographs of 5000 Army recruits ranging from 17 to 4 maxillary right permanent first molar. The extent 26 years of age. Kramer and Williams examined of root formation of the maxillary first molars was 3745 panoramic radiographs of oral surgery patients, one-half on the unerupted right side and three- and found three cases of an impacted mandibular first fourths on the left side. Radiographs revealed a radi- molar but no impacted maxillary first molar cases. olucent area surrounding the of the unerupted Permanent first molars are known as the "key teeth" first molar (Fig 1). When the girl was 8 years old, the in occlusion, and it is very important that the delayed overlying gingiva was surgically excised and the thin permanent first molars be guided to the correct posi- alveolar bone which covered the mesial half of the tion in the dental arch. We encountered four cases of occlusal surface was also removed to expose the tooth. unilateral delayed eruption of maxillary permanent first The specimens were sent for pathological examination. molars at the Pedodontic Clinic of Niigata University In the submucosal layer, there were numerous small Dental Hospital. We diagnosed the patients as having de- islands or cords of odontogenic epithelium among the layed eruption if either more than one year had elapsed mesenchymal fibrous tissue (Fig 2). The pathologi- since the antimere had erupted fully or it did not erupt cal diagnosis was ameloblastic fibroma. Five months at all. According to the research carried out by the Japa- after fene-stration,the maxillary right permanent first nese Society of Pedodontics in 1988,5 the mean age at molar erupted spontaneously. die time of eruption of the maxillary permanent first molars is 6 years 8 months ± 8 months for Japanese boys ]4 Fig 1. Case 1. Panoramic radiograph showing a radiolucentarea surrounding the crown of the unerupted maxillary right permanent first molar. > Fig 2. Case 1. Photomicroghaph of the excised gingiva IH&E, original mag. 50x1. There are numerous small island or cords of odontogenic epithelium amond the mesenchymal fibrous tissue.

Pediatric Dentistry - 20:1, 1998 American Academy of Pediatric Dentistry 53 Case 2 nosis was ameloblastic fibroma with tooth-like structure. An 8-year, 3-month-old Japanese boy was diagnosed After the second operation, the unerupt-ed first molar as having delayed eruption of the maxillary left perma- began to erupt spontaneously. nent first molar based on the panoramic radiograph ob- Case 3 tained during a dental check-up at our clinic. The A girl aged 10 years, 3 months was diagnosed with contralateral counterpart had erupted at the age of 7 years, delayed eruption of the right maxillary first molar. The 7 months. There was no swelling or redness of the gin- maxillary left permanent first molar had erupted when she giva in the maxillary left first molar region. Radiographic was 6 years, 2 months old, but the right first molar had examination (Fig 3) revealed that the impacted maxillary not erupted until she was 9 years, 8 months old, at which left first molar was located near the left maxillary sinus, time the maxillary right permanent first molar and second and there was a radiolucent area containing a small, ra- had begun to erupt together. The second pre- diopaque mass situated occlusal to the left first molar, pre- molar erupted fully but the first molar did not. Radio- venting eruption. The root development of the maxillary graphic examination revealed nothing that would prevent permanent first molars was one-fourth on the unerupted the eruption (Fig 5). When she was 10 years, 3 months left side and three-fourths on the right side. The tooth old, the overlying gingiva of the right permanent first mo- formation of the maxillary left permanent second molar lar was surgically excised and the occlusal surface exposed. adjacent to the affected first molar was also delayed com- After surgery, there was no further eruption and orthodon- pared with the antimere. On the normal right side, the tic traction was applied. At the age of 10 years, 10 months, tooth crown of the maxillary permanent second molar had she showed full eruption of the maxillary right perma- already calcified, while on the left side the calcification of nent first molar (Fig 6). The excised gingiva was exam- the tooth crown was at the initial stage. The gingiva over- ined microscopically, and it showed hyperplastic myxoid lying the left permanent first molar was excised twice, first tissue of the submucosal layer. The histopathological di- when the patient was 8 years, 5 months and then at 9 years, agnosis was myxofibrous tissue of the gingiva (Fig 7). 1 month, and the specimens were sent for pathological ex- amination. Microscopically, islands or cords of odontoge- Case 4 nic epithelium that resembled dental papillae were observed A 7-year, 7-month-old girl was brought to our clinic among the mesenchymal tissue (Fig 4). A small mass of because of cross bite of the maxillary right permanent calcified tissue was identified as immature enamel matrix lateral . The first oral examination revealed that covered with enamel epithelium. The pathological diag- the maxillary right permanent first molar had fully

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Fig 3. Case 2. Panoramic radiograph showing a radiolucent area with a small radiopague mass occlusal to the maxillary Ion permanent first molar. Fig 4. Case 2. Photomicrograph showing Fig 5. Case 3. Periapical radiograph The tooth formation of the maxillary the odontogenic epithelial Islands (OEl in showing the unerupted maxillary right left second molar adjacent to it is also the mesenchymal tissue which resemble permanent first molar (arrow!. delayed compared with the antimere. dental papillae (H&E. Original nag. 25x1.

Flg 6. Case 3. (Al Clinical intraoral views showing the absence of the maxillary right permanent first molar at the age of 10 yr, 3 mo. (B) Partial eruption during applied traction. (Cl Full eruption at he age of 10 yr. 10 mo Omirror image).

54 American Academy ofPediarric Dentistry Pediatric Dentistry - 20:1, 1998 Author Year Age Sex Location Treatment Histology Miller7 1976 6yr, 6mo M enucleation of the ameloblastic fibro- lesion and impacted odontoma first molar 12 y, 6 mo M curettage ameloblasticfibro- odontoma 12 y M maxilla curettage ameloblasticfibro- odontoma Grove? 1985 28 y M maxilla surgical removalof odontoma the odontoma and impacted first molar Goho8 1987 7yr F mandible surgical removalof dense, fibrous the overlying soft connective tissue tissue Spratley9 1988 9y F mandible radical exposureof the tooth Matsuyama1° 1991 13yr, 2 mo M mandible enucleation of ameloblastic fibro- the tumor odontoma 10yr, 6mo M mandible enucleation of complex odontoma the tumor 9yr, 2mo M mandible enucleation of odontogenic fibroma the tumor 8yr, 8 mo F mandible enucleation of ameloblastic fibro- the tumor dentinoma erupted but the left one had not emerged.The pan- delayed eruption of permanentfirst molars. The oramicradiograph, obtained when she was8 years, 1 systemicfactors 6 includea familialtendency to retar- monthold, showedthat the root formationof the left dation of eruptionand metabolicor endocrinedistur- first molarwas in the beginningstage andthat on the bances.Local factors’ are odontogenictumors (such as right side wasone-third. The tooth developmentof the ameloblasticfibroma, odontogenic fibroma, and odon- neighboringmaxillary left secondmolar was also delayed toma), cysts, malformedteeth, supernumeraryteeth, comparedwith that of the right molar(Fig.8). Weob- delayedtooth development,insufficient arch space,in- servedthe left first molarfor 9 monthsand when she clination against the secondprimary molar, and mu- was8 years, 10 monthsold she wasdiagnosed as hav- cosal barrier due to gingival fibrosis6. Thetable ing delayederuption of the maxillaryleft first molar. summarizesthe reportedcases 3’ 7-,0 of the impactionor Theoverlying gingiva was surgically excised. The first delayederuption of the permanentfirst molars,includ- molarstarted to erupt 1 monthafter the excision.Mi- ing mandibularmolars. Because the age at detectionin croscopicexamination revealed immature collagen fibers mostreported cases is around10 years, pediatric den- irregularlydistributed in the myxoidtissue under the hy- fists are morelikely than general practitioners to encoun- perplasticmucosal epithelium, as wellas odontogenicepi- ter anddiagnose such cases. In mostcases, odontogenic thelial islands(Fig 9). Thepathological diagnosis was tumorwas a contributingfactor, as shownin the Table. myxofibroustissue of the gingiva. Whenthe delayederuption is causedby local factors, Discussion unilateralfailure usually occurs. In our cases,the fail- ure of eruptionwas unilateral, for whichlocal factors Thereare systemicand local factors that influence are indicatedas the mostlikely cause.In twocases each,

PediatricDentistry - 20.’1, 1998 AmericanAcademy of Pediatric Dentistry 55 the pathological diagnosis was ameloblastic fibroma or cally observe the patient and then decide whether sur- myxofibrous tissue. These odontogenic tumors and fi- gical intervention is necessary. After surgical interven- brous tissue impeded tooth emergence. Kramer et al.11 tion, we observe the condition and if we cannot pointed out that a dental follicle may become thickened recognize any tendency to erupt, we apply traction. when a tooth fails to erupt and that the thickened folli- Dr. Tomizawa is an associate professor, Dr. Kohno an assistant pro- cular fibrous tissue is often myxoid. fessor, Dr. Yonemochi a clinical instructor, and Dr. Noda a pro- The tooth development of all the unerupted maxil- fessor, at the Department of Pedodontics, School of Dentistry, lary permanent first molars was delayed compared with Niigata University, Niigata, Japan. Reprint requests should be sent to Dr. Mieko Tomizawa, Department of Pedodontics, School of that of their counterpart. In two cases, the maxillary per- Dentistry, Niigata University, Niigata, Japan. manent second molars adjacent to the affected first mo- lars also showed delayed development. This indicates References that delayed tooth formation on the affected side may 1. Johnsen DC: Prevalence of delayed emergence of perma- be one reason for delayed eruption. nent teeth as a result of local factors. J Am Dent Assoc As to the treatment of the delayed eruption of the 94:100-106,1977. maxillary permanent first molars, surgical intervention 2. Dachi SF, Howell FV: A survey of 3874 routine full- is required. The surgical objective is to remove the im- mouth radiographs. IL A study of impacted teeth. Oral Surg Oral Med Oral Pathol 14:1165-69, 1961. pediment and to assist eruption by exposing the crown. 3. Grover PS, Lorton L: The incidence of unerupted perma- After exposure of the crown, we usually observe the site nent teeth and related clinical cases. Oral Surg Oral Med Oral for 3 months, using radiography if the wound closed Pathol 59:420-25, 1985. following surgical exposure. In some cases, as in case 2, 4. Kramer RM, Williams AC: The incidence of impacted teeth. A survey at Harlem hospital. Oral Surg Oral Med Oral Pathol a second surgical exposure may be necessary. If no ten- 29:237^1, 1970. dency to erupt is recognized, then traction is applied as 5. The chronology of deciduous and permanent dention in Japa- in case 3. When the tooth development of the adjacent nese children. The Japanese Society of Pedodontics. Shoni second molar is also retarded and there are no pathologic Shikagaku 26:1-18,1988. 6. Di Salvo NA: Evaluation of unerupted teeth: orthodontic findings on die radiograph, we can keep the patient un- viewpoint. J Am Dent Assoc 82:829-35, 1971. der periodic observation as in case 4. Our treatment in 7. Miller AS, Lopez CF, Pullon PA, Elzay RP: Ameloblastic all four patients involved exposure of the tooth crown, fibro-odontoma. Report of seven cases. Oral Surg Oral Med and traction was applied in one case. All four delayed Oral Pathol 41:354-65,1976. 8. Goho C: Delayed eruption due to overlying fibrous connec- maxillary first molars erupted satisfactorily. tive tissue. ASDC J Dent Child 54:359-60, 1987. 9. Spratley MH, Symons AL, Monsour FN: Unerupted first Conclusions permanent molar.Case report. Aust Dent J 33:392-94,1988. When we encounter a case of delayed eruption of 10. Matsuyama J, Tomizawa M, NodaT, Suzuki M, Fukushima first permanent molars, we remove the overlying tissue M: Four cases of odontogenic tumors causing delayed erup- tion of lower permanent first molars. Jpn J Ped Dent 29:447- or pathological lesions surgically to expose the crown 58, 1991. after checking the radiograph. When the development 11. Kramer IRH, Pindborg JJ, Shear M: Histological Typing of both the first and second molar is retarded and there of Odontogenic Tumors, 2nd Ed. Berlin: Springer-Verlag, are no pathological radiographic findings, we periodi- pp 23, 1992.

Fig 8. Case 4. Panoramic radiograph showing slight enlargement of the Flg 7. Photomicrograph showing the follicular sac of the maxillary left Fig 9. Case 4, Photomicrograph showing hyperplastic myxoid tissue of the permanent first molar. The root formation immature collagen fibers irregularly submucosal layer (H&E, orig. mag 25x1. of the molar is in the beginning stage distributed in the myxoid tissue and while that of the right counterpart is one- odontogenic epithelial islands (Oil (Hat third. The tooth development of the orig mag. 25x1 neighboring maxillary left second molar is delayed compared with the antimere.

56 American Academy ofPediatric Dentistry Pediatric Dentistry -20: J, 1998