RESUMO
AIM: To evaluate the diagnosis of simulated external root resorption in cone beam computed tomography (CBCT) images acquired with different voxel sizes, then reconstructed with the same voxel size. METHODOLOGY: Buccal, mesial and distal root surfaces of twenty single-rooted premolar teeth were evaluated for the presence or absence of simulated resorption defects. Images were obtained using a Classic i-CAT CBCT unit with two different voxel sizes (0.25 and 0.30 mm). Then all images were reconstructed to 0.25 mm voxel size. The McNemar's test was applied to evaluate the agreement between the two protocols (different voxel sizes/reconstruction parameters) with the gold standard (defects created in the root). Accuracy, sensitivity, specificity, positive and negative predictive values were calculated for each voxel and defect sizes. RESULTS: Better sensitivity and accuracy were obtained with 0.25 (0.25 mm) voxel size. Specificity, positive and negative predictive values were highest with the 0.25 (0.30 mm) voxel size. McNemar's test results revealed significant differences between the protocols with the gold standard (P < 0.0001). The results revealed that as the cavity size increased, sensitivity, accuracy, positive and negative predictive values also increased. When correlating the voxel size and root third, better sensitivity, accuracy, positive and negative predictive values were obtained in the middle third. CONCLUSIONS: In the diagnosis of simulated external root resorption with the Classic i-CAT CBCT unit, images acquired with 0.30 mm voxel size and reconstructed with 0.25 mm voxel size provided the best protocol with a lower radiation dose than the 0.25 mm voxel size.
