On a periapical radiograph, you identify a tooth within a tooth appearance (a radiopaque calcified structure entirely within the pulp space of a tooth). What is the MOST likely diagnosis?

Dens in dente (dens invaginatus) literally means 'tooth within a tooth' — it results from invagination of the enamel organ before calcification. On radiograph, it shows an enamel-lined invagination extending from the cingulum into the pulp, creating a tooth-within-a-tooth image. Most commonly affects maxillary lateral incisors. Highly associated with pulp necrosis due to the invagination trapping bacteria. Classified using Oehler's classification (I, II, III).