A comparison of the diagnostic accuracy of CBCT images of different voxel resolutions used to detect simulated small internal resorption cavities

Abstract

To assess ex vivo the use of two different cone-beam computerized tomography (CBCT) units at different voxel resolutions for the detection of simulated small internal resorption cavities. A total of 60 single-rooted mandibular incisors and canines were split mesiodistally along the coronal plane into labial and lingual sections. Artificial internal root resorption was simulated by drilling with a 0.5-mm-diameter round bur to its full depth at either the cervical or apical portion of the labial wall. In total, 60 cavities were created (30 cervical and 30 apical), and 60 locations (30 cervical and 30 apical) were left without cavities. The sections were rejoined and placed in dry human mandibles in groups of 6 and imaged using two different CBCT units at different resolutions to obtain five image sets as follows: Iluma, ultra-resolution (0.1 mm(3)); Iluma, high-resolution (0.2 mm(3)); Iluma, low-resolution (0.3 mm(3)); 3D Accuitomo 170, 6 x 6 cm FOV (0.125 mm(3)); 3D Accuitomo 170, 8 x 8 cm FOV (0.160 mm(3)). Each image set was viewed by two observers and evaluated using a 5-point scale for detection of internal resorption cavities. Kappa coefficients were calculated to assess intra- and inter-observer agreement. Az values were calculated and compared, with a significance level of alpha = 0.05. Kappa values were fair-to-moderate for the low-resolution Iluma images and good to excellent for all other image sets. Both intra- and inter-observer agreement values were higher for the Accuitomo images than for the Iluma images. The highest Az values were obtained with the Accuitomo 0.125 mm(3) images and the lowest with the Iluma 0.3 mm(3) images. The Az values for the Accuitomo and Iluma ultra- and high-resolution images were higher than those of the low-resolution Iluma images. No differences (P > 0.05) for internal resorption detection were found between the Az values of the Accuitomo 0.125 mm(3), Accuitomo 0.160 mm(3), ultra-resolution Iluma and high-resolution Iluma images. Ultra-and high-resolution Iluma and Accuitomo 0.125 and 0.160 mm(3) CBCT images performed similarly and better than low-resolution Iluma images in the detection of simulated internal resorption ex vivo.