[Respecting apical foramina in the endodontic treatment of confluent canals]

Many dental components (lower incisors, mesial roots of the lower molars, upper bicuspids, the mesiobuccal root of the upper bicuspids, the mesiobuccal root of the upper first molars) have two root canals at cavity level to which two main canals correspond. These two canals either have two separate apical foramina or they merge in the apical third and have a single apical foramen. The endodontist's failure to recognize the latter anatomical characteristic results in deformation of the shared portion of the root canal and laceration of the apical foramen. This in turn leads to disappearance of the tapering cone shape, which acts as a "stop" for the filling material during condensation.