Accuracy of Orthopantomography for Apical Periodontitis without Endodontic Treatment

Introduction: This study aimed to evaluate the diagnostic accuracy of orthopantomography (OPT) for the detection of clinically/surgically confirmed apical periodontitis (AP) without endodontic treatment using cone-beam computed tomographic (CBCT) imaging as the reference standard. Methods: One hundred twenty patients without endodontically treated AP (diseased group) were detected via CBCT imaging using the periapical index system. They were divided into groups of 10 each according to the size of the lesion (2-45 mm and 4.6-7 mm) and the anatomic area (incisor, canine/premolar, and molar) in both the upper and lower arches. Another 120 patients with a healthy root and periapex (healthy group) were selected. Each diseased and healthy patient underwent OPT first and a CBCT scan within 40 days of the OPT. The periapical index system was also used to assess AP by OPT. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for OPT images with respect to CBCT imaging were analyzed. The k value was calculated to assess both the interobserver reliability for OPT and the agreement between OPT and CBCT imaging. Results: OPT showed low sensitivity (34.2), negative predictive value (59.3), and diagnostic accuracy (65.0) and high specificity (95.8) and positive predictive value (89.1). Interobserver reliability for OPT was substantial (k = 0.71), and agreement between OPT and CBCT imaging was fair (k = 0.30). The best and worst identified AP were located in the lower molar area and the upper/lower incisor area, respectively. Conclusions: OPT showed high specificity and positive predictive value. However, overall, it was not an accurate imaging technique for the detection of untreated AP, especially in the incisor area.