Family study of a rare case with fused molars

Objectives: The incidence of fusion on permanent posterior is rare. Recently we successfully treated the fusion of the permanent mandibular second and third molars with nonsurgical endodontic therapy and this case is combined with congenitally missing lateral incisors. The purpose of this study was to clarify the possible genetic background and relation of the dental anomalies. Methods: 23 family members were investigated including careful clinical and panoramic radiographic examination on the basis of informed consent. Results: Among 23 examined family members, 8 suffer from various forms of dental anomalies including invaginated incisors (3 members), abnormal central cusps (2 members), microdontia (2 members) or congenitally missing lateral incisors (4 members). Some of the anomaly were shared by the affected members. However, no single form of the anomaly transmitted from parents to offspring was found. Conclusions: A variety of dental anomalies, with the congenitally missing lateral incisor as the major trait, was found in the family, and the frequency is obviously higher than that of ordinary population. We can not rule out the genetic explaination to this case. Further genetic study of this family is necessary.