Is the inferior occlusal plane a reliable anatomic landmark for inferior alveolar nerve block? A study on dry mandibles of Brazilian adults.

PURPOSE: To investigate the relationship between the mandibular foramen (MF) and the inferior occlusal plane (IOP) of anatomic specimens, in order to guide clinicians in the inferior alveolar nerve block (IANB). METHOD: Eighty-two dry mandibles (totally or partially toothed) of Brazilian adults were selected, totalizing 66 left and 66 right antimeres. A flat plate of rigid PVC plastic was placed on the occlusal surfaces of posterior teeth and pressure was then manually applied to simulate the IOP. Following, the perpendicular distance from the IOP to the lowest point of the MF was measured by the use of a digital caliper, adopting negative values inferiorly and positive values superiorly. RESULTS: Regarding the antimeres, the majority of the lowest limits of the MF was below the IOP (right: 86.4%, left: 81.8%) with a mean of -4.2mm (±4.8) in the right and -4.1mm (±4.8) in the left ones, without any statistical significance. Considering both sexes, no statistically significant difference was obtained between them. CONCLUSION: The IOP seems not to be a good anatomical landmark to localize the MF and, its turn, to guide clinicians during the IANB for Brazilian adults, given the marked topographic variations.