Prevalence and measurement of anterior loop of the mandibular canal using CBCT: A cross sectional study

BACKGROUND: Anterior loop of the mental nerve is a very important anatomic landmark in implant placement and anterior mandibular osteotomies. PURPOSE: Two-dimensional imaging techniques are not competent enough to locate and measure the mental nerve loop in majority of the cases. Any injury to this loop results in pain/paresthesia/numbness in the region supplied by the mental nerve. The aim of this study is to analyze the prevalence and measure the length of the loop using cone beam computerized tomography (CBCT) and calculate the average length and prevalence so that a safe margin can be given while placing the implants or the osteotomy cuts in the premolar region. MATERIALS AND METHODS: A cross-sectional study was done using CBCT images of 85 patients taken for impaction surgery. The length of the loop was measured in mm using standardized lines drawn along specific anatomic landmarks. RESULTS: In our study 11.76% of patients had anterior loop in their mental nerve. Mean length of the mental nerve loop was calculated and found to be 2.79 mm. CONCLUSION: A margin of 4 mm anterior to the mental foramen should be safe to avoid any damage to the mental nerve loop bundle in majority of the cases where the loop is present.