Darkening of third molar roots: panoramic radiographic associations with inferior alveolar nerve exposure.

PURPOSE

The aim of the present study was to examine the association between the darkening of the root on the preoperative panoramic radiograph and intraoperative inferior alveolar nerve (IAN) exposure.

PATIENTS AND METHODS

In the present study, 116 mandibular third molar surgical extraction cases with darkening of the third molar roots on the preoperative panoramic radiographs were selected for a case group, and 193 patients with one or more of the following "high-risk" signs, indicating a close spatial relationship between the root and dental canal, were selected for the control group: interruption of the white line, diversion of the canal, and/or narrowing of the canal. The correlation between the radiographic markers and IAN exposure was estimated using bivariate analysis.

RESULTS

The IAN was visible in 47 (15.2%) of 309 intraoperative extractions. Darkening of the third molar roots was significantly associated with IAN exposure (P < .001). Those with both darkening and adjacent "high-risk" radiographic markers present simultaneously had a significantly greater risk of IAN exposure than those with darkening only (P < .001) or any other combination of multiple high-risk factors (P = .001).

CONCLUSIONS

Significant differentiation between isolated darkening and darkening with both adjacent and high-risk signs seems to be essential in predicting IAN exposure.