Fusion of maxillary primary central and lateral incisors bilaterally.

A case of bilateral fusion is presented, the definitions of fusion and gemination are reviewed, as well as the diagnostic criteria. The clinical implications of fused teeth include the probability of loss of arch length, caries susceptibility of the fissure, and missing corresponding permanent incisors. Introduction In 1963 Tannenbaum and Ailing, defined gemination as the formation of the equivalent of two teeth from the same follicle, with evidence of an attempt for the teeth to be completely separate, this indicated clinically by a groove or depression which could delineate two teeth. Radiographically, there appears to be only one pulp chamber. They stated that in gemination, if the bifid tooth is counted as one entity, the total number of teeth in the dental arch is otherwise normal. The same authors' defined fusion as a union of two separate tooth buds at some stage in their development. Depending on the stage they are united, one tooth may have only one pulp chamber as a gemination, or there may be two pulp chambers, with union only of the dentin. Fusion and/or gemination of primary teeth is more frequent than among permanent teeth. Data available for the primary dentition combined the prevalence of fused and geminated teeth, the conditions being relatively frequent, ranging from 0.5 percent to 2.5 percent according to the population surveyed. Fusion of the lateral incisor and cuspid is the most common of these manifestations in the primary dentition, and symmetrical occurrence is often found. This article reports on a case of bilateral fused primary incisors, with a discussion of clinical implications and further elaboration of the definitions of gemination and fusion.