Comparison of orthopantomography and CT accuracy in predicting inferior alveolar nerve injury following lower third molar surgical extraction

BACKGROUND: The aim of this study was to compare orthopantomography (OPG) and computed tomography (CT) accuracy in predicting inferior alveolar nerve (IAN) injury after lower wisdom teeth extraction. METHODS: Twenty-three patients with completely impacted lower third molars were enrolled in this study and OPG and CT exams were obtained before surgical intervention. Finally, a total of 26 lower third molars were extracted and cases of paresthesia following a IAN lesion have been registered. Then, OPG and CT images of the same patients have been randomly submitted to four experienced oral surgeons (with a seniority of at least 5 years) who were required to predict the possibility of a IAN injury by only evaluating the radiological exams. The images were anonymous and have been submitted to the surgeons without an order avoiding to influencing the answers. The agreement between the predicted and the real outcomes was statistically evaluated using the positive predictive value (PPV), the negative predictive value (NPV), Sensitivity, Specificity and the Spearman's rank correlation coefficient. RESULTS: A perfect agreement between OPG-based prevision and the real development of paresthesia due to IAN injury has been observed. This agreement was only moderate when considering CT images. CONCLUSIONS: OPG is a first-level diagnostic exam that provides enough information for predicting IAN lesions after impacted lower third molars surgery. CT is a second-level radiological exam that provides more information on roots morphology and on the amount of the contiguity between roots and mandibular canal resulting useful in performing a minimally invasive surgery.