Dens invaginatus type III in a mandibular premolar.

Dens invaginatus is a developmental malformation of teeth that frequently provides a route for bacterial infection of the dental pulp. It is most commonly seen in the maxillary lateral incisor. This case report describes a Type III dens invaginatus of the mandibular first premolar, with associated acute apical periodontitis. The invagination was treated by endodontic instrumentation and obturation, followed by coronal restoration using a glass ionomer base, and an occlusal composite resin. The pulp of the tooth tested vital upon presentation, and remained vital throughout treatment. Practitioners are reminded to carefully evaluate teeth with dens invaginatus for the possibility of maintaining pulp vitality.