Topographical Landmarks for Identification of Inferior Alveolar Nerve and its Surgical Implications - a Cadaveric Study

Abstract

Background: Inferior alveolar nerve, which arises from the posterior division of the mandibular nerve, contains both sensory and motor fibres. The intraosseous course of the nerve is variable. Mandibular foramen is situated on the medial surface of the mandibular ramus. It is an important anatomical landmark for procedures like sagittal split osteotomies and inferior alveolar nerve block.Methods: The precise location of mandibular foramen was studied by the dissection of formalin fixed cadavers available for undergraduate dissection for a period of two years fron 2014-2016. Results: The mandibular foramen was 21±3.33 mm superior to the gonion at an angle of 980±50 with the base of the mandible. The mandibular foramen was 20.13±3.1 mm inferior to the lowest point of the mandibular notch. Accessory mandibular foramen was observed in 9.37% of the samples dissected.Conclusion: The present study explains the position of mandibular foramen in relation to prominent bony landmarks and the knowledge about the mandibular foramen, helps dental surgeons during inferior alveolar nerve blocks and split osteotomies.Practical implications: Failure rate of the inferior alveolar nerve block has been reported to be approximately 20-25%. A thorough anatomical knowledge of the mandibular ramus is essential for inferior alveolar nerve blocks and sagittal split osteotomies, since they are technically difficult procedures and as they are also associated with a higher incidence of complications.