Evaluation of prevalence and length of the anterior loop of mental nerve using cone beam computed tomography

The anterior loop (AnL) of the mental nerve is anatomically defined as the segment where the neurovascular bundle courses anteriorly and inferiorly to the mental foramen (MF) before looping back to exit through it. This structure is a critical consideration in determining optimal implant placement in the mandibular premolar region. The MF itself is an essential anatomical landmark, particularly for effective local anesthesia and for minimizing the risk of iatrogenic injury during surgical procedures in the premolar area. Cone-beam computed tomography (CBCT) enables enhanced visualization of anatomical landmarks, offering precise localization, delineation, and assessment of their spatial relationships. Accordingly, CBCT is recommended when detailed anatomical information is required, such as in the identification and evaluation of the AnL.

This study was designed to evaluate the vertical and horizontal positioning of the MF and to assess the visibility, classification, and length of the AnL using CBCT in dentate and edentulous patients across various age groups.

A retrospective analysis was performed on 260 mandibular CBCT scans to determine the location of the MF and the presence, type, and length of the AnL. Associations between these parameters and patient age, gender, mandibular side and dental status were statistically analyzed.

The overall frequencies of AnL types 1, 2, and 3 were 7.7%, 20.8%, and 71.5%, respectively. The mean AnL length was 2.75 mm, with a range of 0.6 mm to 6.7 mm. Statistically significant differences in AnL prevalence were identified across age and dental status groups, while AnL length varied significantly with respect to gender, age, and dental status. Additionally, the vertical position of the MF was significantly correlated with both AnL prevalence and length.

The findings indicate a high prevalence of the AnL, underscoring the necessity of evaluating its presence and length in preoperative planning to mitigate the risk of neurovascular injury during maxillofacial surgical procedures.