Three independent canals in the mesial root of a mandibular first molar.

Endodontic therapy was performed in a mandibular first molar with three canals in the mesial root. The mesiobuccal and the mesiolingual canals were found in their normal locations. The third was located in the middle of the distance between the other two. Radiographically, it ended in its own distinct foramen. Many reports deal with three orifices in the mesial root, but very few describe three independent canals, indicating a rare anatomical configuration. To locate the third possible intermediate canal it was suggested to reduce the mesial dentinal wall of the pulp chamber after instrumenting the main two canals.