DIAGNOSTIC ACCURACY OF CBCT VERSUS PANORAMIC RADIOGRAPHY IN PREOPERATIVE ASSESSMENT OF IMPACTED THIRD MANDIBULAR MOLARS PROXIMITY TO INFERIOR ALVEOLAR NERVE: A SYSTEMATIC REVIEW

Abstract

Background: The risk of Inferior alveolar nerve injury is the biggest risk factor in surgical extraction of mandibular third molars. A pre-operative assessment can minimize this issue greatly. The most widely used radiographic technique is OPG which due to its 2D nature over and under diagnoses the risk. Cone Beam Computed Tomography (CBCT) provides three-dimensional imaging that overcomes these spatial limitations.

Objective: To assess the diagnostic accuracy of CBCT in comparison to panoramic radiography in preoperative assessment of impacted third mandibular molars and its relation to Inferior Alveolar Nerve.

Materials and Methods: Electronic databases (PubMed/MEDLINE, Embase, Scopus, and the Cochrane Library) were searched for studies published up to 2026 following PRISMA guidelines. Risk of bias was assessed using the QUADAS-2 tool. Studies evaluating the proximity of inferior alveolar nerve to mandibular third molar were included.

Results: A total of 5 studies were included that met the inclusion criteria. Five studies meeting the criteria were included. On the OPG "darkening of roots" and "interruption of the canal white line" correlated significantly with the loss of cortication on the CBCT. Panoramic radiograph demonstrated high sensitivity but low specificity. This was opposed to the CBCT findings where true root to canal contact was observed in 58.6% to 76.6% of radiographically high-risk cases. Moreover, CBCT correctly produced reproducible results with results to lingual canal path which often resulted in perforation. OPG was also significantly inadequate for detecting multiple roots (P < 0.05).

Conclusion: CBCT provides vastly superior diagnostic accuracy in determining the proximity of the nerve to the third mandibular molar root, lingual canal pathway, multiple roots and true canal perforation.