The Mandibular Canal: A Study to Determine If Cortical Bone Exists as a Protective Roof for the Inferior Alveolar Nerve

Placement of dental implants has many inherent risks, of which all clinicians must be aware. One of the most important concepts in dental implantology is avoidance of the vital structures present in the human jaws, which can have both immediate as well as long-standing implications. The inferior alveolar nerve (IAN) is one of these vital structures located in the posterior body of the mandible. Invasion of this sensory nerve with a dental implant can result in transient or permanent paresthesia, anesthesia, or dysesthesia. Radiographic imaging is done routinely order to assess the bone volume prior to implant surgery and plan for a safety zone above the IAN. The IAN is contained within the mandibular canal, and this structure is usually visualized during cone-beam computerized tomography (CBCT) scans. The mandibular canal, as it is viewed on CBCT, appears to have a cortical layer of bone protecting the IAN, and clinicians often discuss a bony layer of protection that can be felt by the clinician during osteotomy preparation. The purpose of this research project was to ascertain whether the mandibular canal has continuous or partial remnants of cortical bone lining the roof of the canal or whether the IAN simply travels through spongy, cancellous bone with no cortical bony protection.