The pulp of two teeth appears to be SHARED (common pulp chamber). Which dental abnormality is this?

Correct answer: A. Fusion

• A. Correct. FUSION is the union of two SEPARATE tooth buds to form ONE enlarged tooth with a SHARED (common) pulp chamber. Because two buds joined, the tooth count is reduced by one (one fewer tooth than expected). Fusion produces a large tooth with a shared or partially shared pulp.
• B. Incorrect. Concrescence is fusion of adjacent tooth roots by cementum, with SEPARATE crowns and separate pulp chambers — the pulps are NOT shared.
• C. Incorrect. Gemination is an attempt of ONE tooth bud to divide, creating a large BIFID tooth that still counts as ONE tooth in the dental formula. The pulp is continuous within that one enlarged tooth.
• D. Incorrect. Dens in dente (invagination) is an infolding of the enamel organ into the dental papilla — creating a 'tooth within a tooth' — but NOT a shared pulp between two separate teeth.