Comparative efficacy of spiral computed tomography and orthopantomography in preoperative detection of relation of inferior alveolar neurovascular bundle to the impacted mandibular third molar.

PURPOSE: To assess the relationship of the inferior alveolar neurovascular canal (IANC) and the impacted mandibular third molar on spiral computed tomography (SCT), determine the validity of this assessment, and compare it with that for an orthopantomogram (OPG).

MATERIALS AND METHODS: Patients visiting the Oral and Maxillofacial outpatient department at the Government Dental College and Hospital, Nagpur, India, were chosen as the subjects for our study. Patients were operated on and the actual clinical findings were compared with the SCT findings. Sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve were determined as a part of ROC analysis. The values for both the diagnostic modalities were then compared using a chi(2) test.

RESULTS: Objective evaluation of the SCT showed that the number of positive clinical findings (marking on tooth surface, visualization of the neurovascular bundle, intraoperative excessive hemorrhage, and IAN paresthesia) were significantly more in patients with no measurable distance between the tooth and the canal. Also, the positive clinical findings were observed significantly more in patients who had the following features observed on spiral CT: lack of cortication of the canal and lingual or intraradicular course of the inferior alveolar neurovascular bundle (IANB). ROC analyses of both these diagnostic modalities have shown that the SCT performed better than OPG, although the difference is not statistically significant (P = .9871; chi(2) test).

CONCLUSIONS: The spiral CT images definitely enhanced the visualization of the relation of the tooth to the IANB, which might provide a higher level of intrasurgical safety and safeguard the interests of both the surgeon and the patient.