Overall: Mandibular third molar extraction is a routine operation in dental practice. However, there is an increased risk of nerve damage after surgery. The development of CBCT has supported diagnosis and treatment.

Purpose of research: to evaluate the relationship between the mandibular third molar and the inferior alveolar nerve bundle by cone beam computed tomography

Method of research: the study was conducted on108 mandibular third molar of 59 patients (25 men, 34 women) in Thai Nguyen province.

Result: The inferior alveolar nerve bundle contact the mandibular third molar accounted for the rate of 38,9%. The inferior alveolar nerve bundle is at the lower position relative to the root of the mandibular third molar ( contact and non-contact) accounting for the highest rate of 63%, the angle between the inferior alveolar nerve bundle and the root of the third molar is from 0 to 30 degrees, accounting for the highest rate of 33,3% and the shortest distance from the neural tube to the root of the third molar > 3mm accounted for the highest rate was 48.5%.