Unusual mandibular canine transposition: A case report Naphtali Brezniak, MD, DMD, MSD,' Amos Ben-Yehuda, DMD, b and Yehoshua Shapira, DMD ~ Tel Aviv, Israel
T o o t h transposition is a unique type of ectopic eruption in which two teeth have interchanged positions in the dental arch.' This phenomenon has recently been extensively reviewed in the literature, and several treatment modalities have been reported."
"Lt. Colonel, head of the Orthodontic Department, Israel Derence Forces; Instructor, Orthodontic Department, Maurice and Gabriela Goldsehlager School of Dental Medicine, Tel Aviv University, bMajor, head of the Periodontic Department, Israel Defence Forces. CSenior Lecturer, Orthodontic Department, Mnurice and Gabriela GoldscNager School of Dental Medicine, Tel Aviv University. AM J ORTHODDENTOFACORTHOP 1993; 104:91-4. Copyright 9 1993 by the American Association of Orthodontists. 0889-5406/93/$1.00 + 0.10 814/35016
Cases of transposition have been reported in either the maxilla or the mandible. The maxillary canine is most frequently involved? High incidence of transposition is reported in the first premolar, 3 less in the lateral incisors, J.4-6and rarely in the central incisor 7 or second premolar? In the mandible, transposition occurs even less frequently, and is reported to involve the canine and lateral incisor only. 9-~ The purpose of this article is to report a case of complete transposition in which the mandibular canine erupted in the midline between the two central incisors. CASE REPORT Clinical examination of a 19-year-old woman referred to the Orthodontic Clinic revealed a Class I molar and canine
Fig. 1. Pretreatment photographs. A, The transposed canine is between the two mandibular central inciscrs. B, Panoramic film. C, Periapical radiograph. The left permanent canine is in the midline. The root of the retained deciduous canine is partly resorbed. 91
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American Journal of Orthodontics and Dentofacial Orthopedics July 1993
Fig. 2. Midtreatment photograph. The 6 mm recession on the buccal surface of the rotated canine.
relation, and a retained mandibular left deciduous canine. The permanent left canine was fully erupted, 90 ~ rotated, in the midline between the two mandibular central teeth (Fig. 1, A). She displayed good oral hygiene with normal gingival contour. No pockets more than 2 mm were found in all involved teeth. The panoramic and periapical radiographs of the involved area are shown in Fig. I, B and C, respectively. T R E A T M E N T PLAN The treatment plan was to extract the retained deciduous canine, to close the extraction space by retracting the incisors, to rotate the permanent canine, and to reshape its crown to fulfill the desired esthetics and function of the anterior mandibular zone. The patient has been informed that there was a possibility of damage to the periodontal support while the permanent canine was being rotated. Such damage could require periodontal therapy and tooth extraction. TREATMENT SEQUENCE After extraction of the mandibular deciduous canine, the patient's mandibular arch was fully bonded. The extraction space was closed mainly by retraction of the incisors, leaving sufficient space for the transposed canine to be rotated. Several months into treatment, the patient disappeared for 4 months during which time the extraction space closed and the canine fully rotated. However, a 6 rnm recession on the canine buccal surface was noted (Fig. 2). Her oral hygiene was poor with a plaque index of 2. The patient was referred for periodontic evaluation. The periodontist decided to cover the gingival defect with a free gingival graft. The procedure took place 2 weeks after the initial preparation, which involved oral hygiene instruction, scaling, and root planing. The follow-up status of the graft, the teeth on debonding, and the final appearance after canine reshaping are presented in Figs. 3 and 4.
Fig. 3. Follow-up status of the free gingival graft. A, One week after the surgery. B, One month after the surgery.
DISCUSSION Developing teeth move within the j a w before eruption. It is not known why a tooth deviates from its normal path o f eruption, often with no apparent cause, and erupts ectopically in a transposed position. Several theories have been proposed to explain the development of this anomaly, including interchange in position o f tooth buds during the very early stages of tooth development, crowding, or resistance of the neighboring teeth, such as a retained deciduous canine, which may deflect the permanent canine from its normal eruptive path. It has been suggested that transposition in the mandible is a result of displacement and distal migration o f the lateral incisor, whereas in the maxilla the displacement o f the maxillary canine is the primary cause o f transposition.2 Unlike previously reported cases of mandibular canine-lateral incisor transposition, the present case demonstrates transposition in which the canine erupted in the midline between the two central incisors.
American Journal of Orthodontics and Demofacial Orthopedics Vohtme 104, No, I
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Fig. 4. Posttreatment radiographs. A through E, Intraoral, F, Periapical radiograph with the permanent splint. G, Extraoral.
Migration apparently starts in the early mixed dentition stage when the mandibular canine assumes a horizontal position and travels mesially and labially to the incisal roots. It may erupt ectopically, but is frequently found
impacted in the same quadrant. Displacement of a mandibular canine from one quadrant across the midline to the other side, referred to as transmigration, is rare and only a few cases have been reported, t2q5 We believe
Brezniak, Ben-Yehuda, and Shapira
that in this case, the displacement of the canine was due to ectopic development of the bud and migration without disturbance along the buccal space of the incisal root. Since the canine was fully erupted in a complete transposition, n o attempt was made to move the tooth to its original position. Therefore the canine was rotated and its crown reshaped to meet the esthetic and functional purposes. Since the c a n i n e root width appeared to exceed the average normal incisal root dimension, it was assumed that the rotation, i f handled properly, will leave the root within the limits of the buccal and lingual plates. Disappearance of the patient at the critical treatment period, together with oral h y g i e n e deterioration coinciding with the local root d i m e n s i o n s , led to severe buccal recession. It was demonstrated that orthodontic forces p r o d u c i n g bodily or tipping movements of teeth out of their alveolar bone envelope resulted in gingival recession in sites of gingivitis. ~6,~7 In patients where buccal recession exists before orthodontic treatment, there is no consensus if or when to cover the defect with a flap. I n the present case, since the recession was a direct result of the treatment, there was no place for preventive periodontal surgery. There is no doubt that there was a need for such a surgery since the defect was functionally threatening the longevity of the canine and esthetically damaging the patient's smile. No attempt was made to m o v e the root lingually, since it would not decrease the gingival defect. Moreover, the root was too wide, and parallel lingual damage was inevitable. It was assumed that a loss of anchorage would have led to more extensive damage of neighboring teeth. Currently, the patient is on a retention recall. If the flap develops signs of recession, the patient, together with the dental team, will c o n s i d e r further treatment, i.e., extraction of the canine. REFERENCES 1. Shapira Y, Kuftinec MM. Maxillary canlne--lateral incisor transposltion--orthodontic management. AM J ORT~OD 1989;95:439-44.
American Journal of Orthodonticsand Dentofaeial Orthopedics July 1993
2. Shapira Y, Kuftincc MM. Tooth transposition--review of the literature and treatment considerations. Angle Orthod 1989;59:271-6. 3. Joshi MR, Bhatt NA. Canine transposition.Oral Surg Oral Med Oral Pathol 1971;31:49-54. 4. Caplan D. Transpositionof maxillarycanine and lateral incisor. Dent Pracfit 1972;22:307. 5. GholstonLR, and Williams PR. Bilateral transpositionof maxillary canineand lateral incisors: a rare condition. ASDC J Dent Child 1984;51:58-63. 6. JacksonM. Transpositionof upper canine and lateral incisor. Br Dent J 1951;90:158. 7. Jackson M. Upper canine in position of upper central incisor. Br Dent J 1951;90:243. 8. Joshi MR, Gaitonde SS. Canine transpositionof extensive degree: a case report. Br Dent J 1966;121:221-2. 9. Platzer KM. Mandibular incisor--canine transposition, J Am Dent Assoc 1968;76:778-84. I0. Shapira Y. Bilateral transpositionof mandibularcanine and lateral incisors: orthodontic managementof a case. Br J Orthod 1978;5:207-9. 11. Shapira Y, Kuftinec MM. Orthodonticmanagementof mandibular canine-incisortransposition.AM J ORTnOD1983;83:271-6. 12. Fidler LD, Ailing CC. Malpositionedmandibularcanine: report of a case. J Oral Surg 1968;26:405-7. 13. Javid B. Transmigrationof impacted mandibular cuspids. Int J Oral Surg 1985;14:547-9. 14. Tarsitano JJ, Wooten JW, Burditt IT. Transmigration of nonerupted mandibularcanines: report of cases. J Am Dent Assoc 1971;82:1395-7. 15. KaufmanAY, Buchner A. Transmigrationof mandibularcanine. Oral Surg Oral Med Oral Pathol 1967;23:648-50. 16. Steiner GG, Pearson JK, AinanoJ. Changes of the marginal pefiodontium as a result of labial tooth movement in monkeys. J Periodont 1981;56:314-20. 17. Wannstr6mJ, Lindhe J, Sinclair F, Thailander B. Some periodontal tissue reaction to orthodontic tooth movement in monkeys. J Clin Periodont 1987;14:121-9. Reprint requests to:
Dr. Naphtali Brezniak #3 Rav-Ashi St. (#31) Tel Aviv, Israel