Endodontic treatment and hypotheses on an unusual case of dens invaginatus.

This work describes a case of "dens invaginatus" and analyzes the possible aspects of this malformation. An unusual type of dens invaginatus was detected in a young patient corresponding to the maxillary lateral incisor and showing extensive periradicular radiolucency and a vestibular fistula. The radiographic and tomographic examination revealed two apices: one wide open in the distal part of the root and the other normally formed in the mesial. Nonsurgical endodontic treatment was performed by using the "one-step apexification technique," filling both apexes with mineral trioxide aggregate followed by composite resin. The follow-up examination 6 months later showed the healing of the radiolucent area and the healing of the sinus tract. Hypotheses on which was the type of dens invaginatus we had to deal with are formulated.