Safe surgical access to the mandibular nerve at the infratemporal fossae.

Abstract

Some anatomic patterns formed by the anterior border of the ascending ramus relative to the mandibular canal can cause nerve complications during surgery. We determined the frequency of obstructive anatomy in patients undergoing jaw surgery, and we described a perioperative method for a bilateral sagittal split osteotomy that ensured inferior alveolar nerve (IAN) protection. The anatomy of the anterior border of the ascending ramus of the mandible was examined on axial and cross-sectional cone beam computed tomographic images of 114 consecutive patients undergoing bilateral sagittal split osteotomies. The thickness of the anterior border of the ascending ramus determined whether the mandibular foramen could be visualized (pattern A) or was obscured (pattern B). Patients with pattern B anatomy received a perioperative procedure. Direct visualization of the mandibular foramen was achieved in 100% of patients with pattern A anatomy. We examined 228 anterior borders of the ascending ramus of the mandible relative to the mandibular foramen in 114 patients. Pattern A was observed in 146 cases (64%); pattern B, in 82 (36%) cases. The use of the nerve hook resulted in no injuries to the IAN in all cases. The described procedure ensured direct visualization of the IAN, which prevented inadvertent damage to the IAN during instrumentation and surgical procedures at the mandibular foramen.