Assessment of the relationships between posterior root apices and the maxillary sinus floor: a comparison of panoramic radiography and cone beam computed tomography.

The aim of this study was to evaluate the relationships between the apices of posterior teeth and the maxillary sinus floor, comparing the results of assessments performed with panoramic radiography and cone beam computed tomography (CBCT). This retrospective cross-sectional study consisted of 96 participants with a total of 302 maxillary posterior teeth. On both panoramic radiographs and corresponding CBCT images, 735 roots were classified into 3 categories according to their topographic relationship with the maxillary sinus: class 1, clear, distinct distance between the root tips and the floor of the sinus; class 2, roots adjacent to the floor of the maxillary sinus; or class 3, roots protruding into the maxillary sinus cavity. Panoramic radiographic signs of root protrusion into the sinus (class 3) were categorized as projection, discontinuity, missing lamina dura, darkening, or kinking. The observed data were analyzed using statistical software, and the Cohen κ coefficient was calculated. The level of significance was set at P < 0.05. Multiple logistic regression was performed to identify the predictive radiographic signs of protrusion into the sinus. The overall correlations between panoramic radiography and CBCT classifications were 90.8%, 66.8%, and 47.1% for the class 1, class 2, and class 3 categories, respectively. The radiographic signs of projection and darkening were significant predictors of root protrusion (P < 0.05). Panoramic radiography is reliable for assessing root posi¬tions when there is a clear distance between the roots and the floor of the maxillary sinus. However, when the roots are in contact with or have protruded into the sinus on panoramic images, the results are not definitive, and CBCT should be performed.