Morphological analysis of mandibular foramen through anatomical planes: implications for inferior alveolar nerve block

Error in localization of mandibular foramen is attributed to a high failure rate of inferior alveolar nerve block in clinical dentistry. We hypothesized that a remodelled approach towards exploring the morphology of mandibular foramen would be useful. In the present study, the location of the mandibular foramen was analysed with respect to the anatomical planes across the ramus of the mandible and also with respect to the quadrants on the medial surface of ramus of mandible. The study was conducted on 50 dry human mandibles of unknown age and sex. The anatomical planes were defined and drawn on the mandibles. Measurements were made with digital Vernier callipers and findings were noted. It was observed that the most consistent position of the mandibular foramen was along the vertical plane, however, the foramen was most likely to be localized along the oblique plane. Morphological analysis of the foramen with respect to the anatomical planes as well as the quadrants on the medial surface of ramus led to the analysis that occlusion plane should be the preferred plane of approach. Moreover, a rectangular area on the medial surface of the ramus was identified posterior to the mid-point of occlusion plane (8 mm above mid-point, 6 mm below mid-point and 6 mm behind mid-point) where the incidence of location of the foramen was significantly high. The findings of this study may potentially reduce the failure rate of inferior alveolar nerve block and clinical complications thereof.