In which of the following dental developmental abnormalities does the pulp of two teeth appear to be SHARED?

Correct answer: C. Fusion

• A. Gemination occurs when a single tooth germ attempts to divide, resulting in a tooth with a large or bifid crown with a SINGLE root and a SINGLE shared pulp canal. While gemination also involves what appears to be two crowns, it arises from ONE tooth bud (not two) — so technically it is one tooth attempting to split, not two teeth joining.
• B. Dens in dente (dens invaginatus) is an invagination of the enamel organ into the dental papilla, resulting in a 'tooth within a tooth' appearance. It is a single tooth anomaly — only one tooth is involved, and there is no sharing of pulp between two teeth.
• C. CORRECT. Fusion is the union of two tooth germs that results in a single, larger tooth structure with a SHARED or partially shared pulp chamber and root canal system. It occurs when two adjacent teeth fuse together during development. On the count, fusion results in one fewer tooth than expected in the arch.
• D. Concrescence involves the fusion of the roots of two fully formed teeth by cementum only (no shared pulp). The crowns remain separate, and the teeth are joined solely at their root surfaces by cementum, not by shared pulpal tissue.