Objectives: The purpose of this study was to compare the diagnostic accuracy of cone beam CT (CBCT) with that of conventional dental radiography in the detection of root fractures and to evaluate the influence of root canal fillings on root fracture detection. Methods: We investigated 128 patients with clinically suspected root fractures in 135 teeth. These patients underwent conventional dental radiography, CBCT and eventually surgical exploration. Among the 135 teeth, 86 were non-endodontically treated teeth and 49 were endodontically treated teeth. Two oral radiologists independently analysed the dental radiographs and CBCT images of each patient and reached a consensus. The CBCT findings of root fractures were set as the detection of a separation of the adjacent root segments on at least two contiguous sections and on at least two of the three-dimensional (3D) planes. Results: Root fracture was intraoperatively detected in 95 of the 135 teeth. The sensitivity and specificity of root fractures diagnosed on the basis of the consensus between the 2 evaluators were 26.3% and 100%, respectively, for dental radiography and 89.5% and 97.5%, respectively, for CBCT. CBCT was significantly more accurate than dental radiography in detecting root fractures (P , 0.001). The sensitivity of CBCT was reduced in the presence of root canal fillings but its specificity remained unaffected. Both the sensitivity and specificity of dental radiography were not influenced by the presence of root canal fillings.Conclusions: CBCT appears to be more accurate than conventional dental radiography in the detection of root fractures.