Determining position of the inferior alveolar nerve via anatomical dissection and micro-computed tomography in preparation for dental implants.

BACKGROUND The inferior alveolar nerve courses anteriorly within the mandibular canal, providing sensory nerve supply to the mandibular teeth, the buccal mucosa, the gingiva, and the soft tissues of the lower lip and chin. To avoid damage to this nerve and resulting sensory disturbances, its exact location must be known before placement of a dental implant. Imaging modalities currently used to visualize the position of the inferior alveolar nerve may be inaccurate. This study was undertaken to determine the accuracy of micro-computed tomography (micro-CT) for determining the position of this nerve. METHODS Micro-CT images of 16 cadaveric hemimandibles were acquired at a slice thickness of 154 µm. Each hemimandible was then sectioned at 6 predetermined locations between the ramus and the mental foramen, to yield 5 corticocancellous bone specimens. The superior, inferior, buccal and lingual distances for bone surrounding the mandibular canal were measured by direct digital caliper and compared with corresponding micro-CT measurements obtained by 3-dimensional visualization and modelling software. RESULTS There was substantial variability in the vertical position of the inferior alveolar nerve, depending on the length of time since tooth loss and the movement of the nerve from the lingual to buccal position as it courses from the posterior to the anterior aspect of the mandible. However, digital caliper and corresponding micro-CT measurements of the thickness of bone surrounding the inferior alveolar nerve were highly consistent, and no significant differences were detected between the two methods of measurement. CLINICAL SIGNIFICANCE The findings reported here confirm the accuracy of micro-CT in determining the location of the inferior alveolar nerve during planning for placement of dental implants in the human mandible.