Together with the maxillary third molar, this tooth displays some of the most irregular canal configurations to be found in the adult dentition, as seen in Figure 11. However, the mesial inclination of the tooth generally makes access easier. The canal orifices are not too difficult to locate, but the degree of curvature of the apical half of the root canal system is often pronounced. Added to this, the apex is frequently poorly developed and lies close to the inferior alveolar canal. A large access cavity allowing direct visualization of the floor of the pulp chamber enables the canal orifices to be identified.
It should always be remembered that whilst the above descriptions are the norm, occasionally other teeth may be encountered with unusual or even bizarre anatomy. This may only be discovered after the treatment has failed and the tooth has been extracted. Clues may sometimes be found by careful examination of the radiographs, especially with the use of magnification, as described in Part 5.