Reliability of Periapical Radiographs and Orthopantomograms in Detection of Tooth Root Protrusion in the Maxillary Sinus: Correlation Results with Cone Beam Computed Tomography

OBJECTIVES The purpose of the present study was to investigate the reliability of both periapical radiographs and orthopantomograms for exact detection of tooth root protrusion in the maxillary sinus by correlating the results with cone beam computed tomography. MATERIAL AND METHODS A database of 1400 patients scanned with cone beam computed tomography (CBCT) was searched for matching periapical (PA) radiographs and orthopantogram (OPG) images of maxillary premolars and molars. Matching OPG images datasets of 101 patients with 628 teeth and PA radiographs datasets of 93 patients with 359 teeth were identified. Four observers assessed the relationship between the apex of tooth root and the maxillary sinus per tooth on PA radiographs, OPG and CBCT images using the following classification: root tip is in the sinus (class 1), root tip is against the sinus wall (class 2) and root tip is not in the sinus (class 3). RESULTS Overall correlation between OPG and CBCT images scores was 50%, 26% and 56.1% for class 1, class 2 and class 3, respectively (Cohen's kappa [weighted] = 0.1). Overall correlation between PA radiographs and CBCT images was 75.8%, 15.8% and 56.9% for class 1, class 2 and class 3, respectively (Cohen's kappa [weighted]  = 0.24). In both the OPG images and the PA radiographs datasets, class 1 correlation was most frequently observed with the first and second molars. CONCLUSIONS The results demonstrated that both periapical radiographs and orthopantomograms are not reliable in determination of exact relationship between the apex of tooth root and the maxillary sinus floor. Periapical radiography is slightly more reliable than orthopantomography in determining this relationship.