Predictive value of panoramic radiography for injury of inferior alveolar nerve after mandibular third molar surgery

Abstract Purpose The purpose of this systematic review was to assess the added value of panoramic radiography in predicting (ruling in or out) postsurgical injury of the inferior alveolar nerve (IAN) in the decision-making before mandibular third molar surgery (MM3 surgery). Materials and Methods MEDLINE and EMBASE were searched electronically to identify the diagnostic accuracy of studies that had assessed the predictive value of 7 panoramic radiographic signs including root-related signs (darkening of the root, deflection of the root, narrowing of the root, and dark and bifid apex of the root) and canal-related signs (interruption of white line of the canal, diversion of the canal and narrowing of the canal) for IAN injury after MM3 surgery. Results A total of 8 studies qualified for a meta-analysis. The pooled sensitivity and specificity of the 7 signs ranged from 0.06 to 0.49, and 0.81 to 0.97, respectively. The area under the summary receiver-operator curve (sAUC) ranged from 0.42 to 0.89. The pooled positive predictive value (PPV) and negative predictive value (NPV) ranged from 7.5 to 26.6% and 95.9 to 97.7%, respectively. The added value of a positive sign for ruling in IAN (PPV minus the prior probability) ranged from 3.4 to 22.2%. The added value of a negative sign for ruling out IAN (NPV minus (1 minus the prior probability)) ranged from 0.1 to 2.2%. Conclusion For all 7 signs the added value of panoramic radiography is too low to consider it appropriate for ruling out postsurgical IAN in the decision-making prior to MM3 surgery. The added value of panoramic radiography for the presence of diversion of the canal, interruption of white line of the canal and darkening of the root may be considered sufficient for ruling in the risk of postsurgical IAN injury in the decision-making prior to MM3 surgery.