A radiograph shows a permanent maxillary lateral incisor with an invagination of enamel and dentin into the pulp chamber; normal size, with a radiolucent groove from the cingulum toward the pulp. Most likely diagnosis?

Correct answer: A. Dens in dente (dens invaginatus)

• A. Correct. Dens invaginatus ('tooth within a tooth') is an infolding of enamel/dentin into the crown/root, classically in the maxillary lateral incisor with a cingulum pit/groove.
• B. A talon cusp is an accessory cingulum cusp — a projection, not an invagination into the pulp.
• C. Gemination is one enlarged tooth from a single bud attempting to divide.
• D. Fusion is the union of two separate tooth buds.