A maxillary lateral incisor shows a radiographic 'tooth within a tooth' appearance from an enamel infolding into the pulp. This developmental anomaly is:

Dens invaginatus (dens in dente) is an infolding of enamel and dentin into the pulp chamber before mineralization, classically in maxillary lateral incisors, giving a 'tooth within a tooth' radiographic look. The invagination predisposes to early pulpal infection.Other options: Dens evaginatus is an outward tubercle; taurodontism is an enlarged elongated pulp chamber; concrescence is the union of two teeth by cementum.Key exam takeaway: 'Tooth within a tooth' in a maxillary lateral = dens invaginatus; seal early to prevent pulp necrosis.