Retrospective Study of the Anterior Loop of the Inferior Alveolar Nerve and the Incisive Canal Using Cone Beam Computed Tomography

Purpose: The mental foramen is an important landmark during surgical procedures such as osseous grafting or the placement of dental implants. To avoid injuring the mental nerve, it is important both to carefully assess the location of the mental foramen and to determine whether an anterior loop of the mental nerve or the incisive canal lies mesial to it. The objective of this study was to quantify the ability of cone beam computed tomography (CBCT) to measure the length of the mental nerve loop, the length and diameter of the incisive nerve canals, and the incisive canal path. Materials and Methods: The study included 352 CBCT scans that had originally been used for preoperative planning of implant placement in the interforaminal region of the anterior mandible. For each scan, the length of the mental nerve loop and the length, diameter, and path of the incisive canal were determined. Mean values were compared between groups based on sex, right versus left side, and whether the patient was edentulous. Results: The inferior alveolar nerve loop and incisive canal had a mean length of 2.40 ± 0.93 mm and 9.11 ± 3.00 mm, respectively. The mean incisive canal diameter was 1.48 ± 0.66 mm and showed a downward path in 51.3% of CBCT images and a linear or upward path in 38.29% and 10.41% of scans, respectively. Conclusions: CBCT provides an accurate means to identify critical anatomical features in the anterior mandible during preoperative surgical planning.