Avaliação do istmo radicular em molares inferiores por tomografia computadorizada de feixe cômico

Abstract

The aim of this study was to evaluate the presence of root isthmus in the mesial root of human lower molars, as well as to compare the influence of different CBCT image acquisition protocols for its detection. 40 healthy human lower molars were used, and their crowns were sectioned at the limit of the cementoenamel junction. The teeth were submitted to micro computed tomography (micro-CT) to elaborate the gold standard and cone beam computed tomography (CBCT) with 4 different acquisition protocols. CBCT scans were evaluated by three examiners for the presence or absence of the root isthmus and its classification (complete or incomplete). The following statistical tests were used: weighted Kappa, Chi-square, ROC curves (sensitivity, specificity and accuracy), one-way ANOVA and McNemar, considering the significance level at 5%. The weighted Kappa test indicated substantial (0.77 - 0.79) to almost perfect reliability (0.91 - 0.94). The isthmus was more prevalent in the apical third, followed by the cervical and middle thirds significantly, being the predominant complete type (p <0.05). McNemar test showed significant difference of all protocols in relation to the gold standard (p <0.05). The highest sensitivity and accuracy values were obtained by protocols that used lower FOVs, regardless of voxel size. It can be concluded that the presence of the root isthmus is common in the mesial root of the lower molars, especially in the apical third. Despite being a structure that is difficult to diagnose by CBCT images, it is more accurate when performed with protocols with smaller FOV size, regardless of voxel size.