C-shaped canals

The C-shaped canal is a special feature of some lower second molars. Approximately 1% of lower second molars have C-shaped canals. The name comes from the appearance of the pulp chamber floor when viewed from above. Some or all of the canal orifices are joined in the form of a groove or isthmus with a shape of the letter C. In teeth with three canals the mesiobuccal canal usually joins the distal canal. In some teeth both mesial canals join the distal canal at the cervical area near the pulp chamber floor. The canals may later, closer to apex, separate again to leave the tooth via separate foramina.