A case report of unusual anatomical variation: externalisation of inferior alveolar nerve

INTRODUCTION: The risks of third molar surgery have been well documented with damage to the inferior alveolar nerve (IAN) being one of the largest concerns. PRESENTATION OF CASE: This case report presents an impacted third molar with associated dentigerous cyst in which the IAN is externalised and runs along the lateral surface of the mandible. DISCUSSION: This is an extremely rare anatomical variation with most IANs lying inferior and lingually to third molars. This case reiterates the limitations of standard radiographic techniques such as the orthopantomogram (OPG). CONSLUSION: We would advocate the use of cone beam computed tomography (CBCT) in cases which have adverse plain radiographic features to allow appropriate surgical planning.