Objective This study aimed to compare the efficacy of cone-beam computed tomography(CBCT) with different voxel resolutions and panoramic radiography for the detection of simulated external apical root resorption(EARR) in vitro. Methods The study sample consisted of 160 single-rooted premolars for simulating EARR of varying degrees according to four setups: no(intact teeth), mild(cavity of 1.0 mm in diameter and depth on mesial, distal, buccal, and lingual root surface), moderate(0.4, 0.8, 1.2, and 1.6 mm root shortening), and severe (2.4, 2.8, 3.2, and 3.6 mm root shortening). These teeth were imaged by CBCT with two different voxel sizes(0.2 and 0.3 mm) and panoramic radiography. Each root was classified according to defect size(no, mild, moderate, and severe) by three calibrated observers using CBCT and panoramic images. McNemar tests were performed to compare the proportions of correct classification between the methods(0.2 mm voxel vs. 0.3 mm voxel, 0.2 mm voxel vs. panoramic, and 0.3 mm voxel vs. panoramic) for each degree of EARR. Results For panoramic radiography, 57.5% of all samples were correctly classified compared with 85% for 0.2 mm voxel and 81.3% for 0.3 mm voxel, and the differences were significant(P<0.01) between both 0.2 mm voxel and 0.3 mm voxel and panoramic radiography. However, no significant difference was observed between 0.2 mm voxel and 0.3 mm voxel in correct classification for no, mild, severe, and all samples(P>0.05). Conclusion CBCT imaging was more reliable than panoramic radiography for detecting simulated EARR. The 0.3 mm voxel resolution was the better configuration because performed the same as the 0.2 mm voxel resolution in diagnosing simulated EARR but with lower exposure to X-rays.
