BACKGROUND AND OBJECTIVE: Injury to the inferior alveolar nerve during extraction of mandibular third molars is one of the serious complications after surgery. Therefore, the precise localization of IAN in relation to the third molar is one of the critical issues before extraction of this tooth. The aim of this study was to evaluate the position of mandibular canal in the mandible and its relation to the roots of the third molar using cone-beam computed tomography (CBCT) in a selected Iranian population.

METHODS: In this cross-sectional study, the CBCT images of 168 patients (214 mandibular third molars) were evaluated. The position of the mandibular canal in the mandible (lingual, central, buccal) and the position of the mandibular canal with respect to the root apex (lingually, centrally and buccally), were recorded.

FINDINGS: Mandibular canals were located lingually in 68.5% of cases, centrally in 27.3% of cases, and buccally in 4.2% of cases(p<0.001). Also, of 355 third molar roots evaluated, 5.4% were located lingually, 26.5% centrally, and 68.2% buccally with respect to the mandibular canal (p<0.001). Furthermore, the position of the mandibular canal in relation to the mesial and distal roots of third molars with separate roots (141 teeth) was different in 25 cases.

CONCLUSION: Considering the results of this study that in most cases the mandibular canal is not in line with the roots of third molars, the use of three-dimensional imaging techniques such as CBCT is essential to the investigation of the relationship between the mandibular canal and the roots of this tooth.