Inferior alveolar nerve injury: Correlation between indicators of risk on panoramic radiographs and the incidence of tooth and mandibular canal contact on cone-beam computed tomography scans in a Western Australian population.

Abstract

The aim of the present study was to assess risks prior to third molar removal. A 2-D panoramic radiograph or a 3-D cone-beam computed tomography (CBCT) scan can be used to visualize the proximity of the third molar to the mandibular canal. We aimed to correlate panoramic indicators of risk with the incidence of contact between these two structures on CBCT scans. Patients were selected from a Western Australian population if they had a panoramic radiograph that illustrated signs of risk of inferior alveolar nerve injury and had a CBCT scan on file. Statistically-significant relationships between the relative position and distance between the mandibular canal and third molar were investigated using χ2 -test and Fisher's exact test in Stata version 13. Within the Western Australian sample (N=100), of six possible panoramic indicators of risk, two were significantly associated with contact between the tooth and mandibular canal on CBCT: (a) interruption of the radiographic white line of the canal; and (b) darkening of the root(s). Two panoramic radiograph risk signs are significantly more likely to indicate contact on the CBCT scans: interruption of the white line and darkening of the root(s). Further research is required to develop CBCT prescription guidelines for surgical planning.