A panoramic radiograph shows the mandibular canine occupying the position normally held by the first premolar, and vice versa. What is this developmental anomaly called?

Correct answer: B. Transposition

• A. Concrescence is the union of two adjacent teeth by CEMENTUM only, after root formation is complete.
• B. Correct. TRANSPOSITION is the positional interchange of two adjacent teeth within the arch — each erupts into the other's normal position. The commonest transpositions are maxillary canine with first premolar and maxillary canine with lateral incisor. Management is a genuine decision point: accept and reshape the transposed positions, or orthodontically correct them, which is difficult and often risks root resorption.
• C. Fusion is the union of two adjacent tooth germs during development, producing one large tooth and a reduced tooth count.
• D. Gemination is a single tooth germ attempting to divide, producing a bifid crown on a single root with a normal tooth count.