Evaluation of the Inferior Alveolar Canal Course in Relation to Fully and Partially Impacted Lower Third Molar Roots via Cone-Beam Computed Tomography.

Introduction: Impacted mandibular third molars are frequently encountered in dentistry. As extraction is often the treatment of choice, knowledge of the proximity and relationship of the inferior alveolar canal (IAC) with the tooth is essential. This study was designed to determine the course of the IAC in cases of impacted lower third molars.

Methods: Cone-beam computed tomography (CBCT) imaging of 103 patients (mean age: 37 years, range: 22-82 years) with 140 impacted lower third molars from 2016 to 2017 was evaluated. The number of roots, type of impaction according to Winter's classification, positional relationship of the IAC in relation to the roots, and shape of the canal were examined.

Results: The most common type of impaction was mesioangular, two-rooted molars. Most often, the canal ran below and in contact with the root, and the canal was most commonly oval-shaped. The type of impaction and the number of roots did not depend on sex. Single-rooted (p = 0.025) and distoangularly impacted (p = 0.019) molars were more common in older patients. There was a significant relationship between the number of roots and the canal running between the roots (p < 0.0001).

Conclusions: There was no relationship between the shape of the IAC and the number of roots or type of impaction. Based on these results, the interesting correlation between age, type of impaction, and number of roots requires further investigation and explanation. The frequency of canals in contact with the root further emphasizes the importance of CBCT imaging for preoperative visualization.