Bilateral fusion of permanent mandibular central and lateral incisors: A case-report of a rare developmental anomaly

Fusion and gemination are two separate clinical entities describing two different morphological and developmental anomalies involving a characteristic large crown that may appear clinically similar. Fusion arises when two normally separated tooth germs fuse or join together during the initiation or the morphodifferentiation stage of tooth development resulting in a single enlarged tooth structure with confluence of dentin, instead of two normal teeth. Although a variety of appearances are noted in both of the anomalies but Kelly suggested that in gemination the two halves of joined crowns are mirror images while fusion manifests with a distinct differences in two halves of the crowns. The prevalence of fusion in primary teeth is 0.4%-0.9% and in permanent dentition it has been reported to be 0.2% only and bilateral fusion in permanent is even more rare and reported to be 0.05%.According to reviewed literature for bilateral fusion in the permanent dentition, only one case of complete fusion of incisors has been reported so far.