Alternative Landmarks of the Mandibular Foramen to Prevent Nerve Injury during Ramus Surgery.

OBJECTIVE: To investigate the mandibular foramen (MF) position in relation to other bony landmarks on the mandibular ramus (MR) to better understand the anatomical landmark during the ramus surgery. MATERIAL AND METHOD: Ninety-two adult mandibles were studied by measuring four linear parameters: AB, the distance from the posterior limit of the MF (point A) to the posterior border of the MR (point B), BC, the MR width (Point C was located at the anterior border of the MR), DE, the distance from the lingula tip (the highest and the most anterior limit of the MF) (point D) to the mandibular notch (point E), and the MR height (EF, point F was located at the mandibular inferior border). Lines BC and EF were drawn through points A and D and parallel to the inferior and posterior borders of the mandible, respectively. These measurements were analyzed to determine the mean parameters related to the MF location. RESULTS: The mean lengths of AB, BC, DE, and EF were 12.7 +/- 2.3, 35.0 +/- 4.0, 17.5 +/- 3.5, and 52.7 +/- 5.2 mm, respectively. The ratios between AB/BC and DE/EF were 0.36 +/- 0.05 and 0.33 +/- 0.05, respectively. This study indicated that the MF located slightly anterior to the posterior third of the MR width and at the superior third of the MR height. CONCLUSION: Anatomical consideration of this area is useful to prevent neurovascular injury when performing the bony cut made in a ramus osteotomy; however, pre-operative examinations with appropriate radiographic analysis are also recommended.