Os tamanhos do FOV e do voxel influenciam na avaliação do istmo de molares inferiores? Um estudo em TCFC

Abstract

Introduction: This study analyzed, through cone-beam computed tomography (CBCT) scans, whether the size of the field of view (FOV) and voxel influence the evaluation of isthmuses in mandibular molars. Methods: Forty human mandibular molars were submitted to microcomputed tomography to obtain the gold standard. Then, they were scanned (ProMax® 3D Max) using seven acquisition protocols, varying in FOV size (10 x 5.5 cm and 5 x 5.5 cm) and voxel (0.400 mm, 0.200 mm, 0.100 mm and 0.075 mm). Two examiners classified the presence and type of isthmus on a five-point scale. To compare the frequency of isthmus detection in each protocol with the gold standard, the chi-square test was conducted. Sensitivity, specificity and accuracy values were calculated for each protocol. Results: Intra- and inter-examiner agreement was verified using the weighted Kappa test and ranged from substantial to almost perfect. The presence of isthmuses was underestimated, especially with a 0.400-mm voxel, regardless of the FOV used. The protocol with 10 x 5.5-cm FOV and 0.200-mm voxel presented the greatest sensitivity and accuracy and the lowest specificity values. Upon comparing all accuracy values, protocol 2 (larger FOV) was better than protocols 4, 5 and 7. Conclusion: Regardless of FOV, the voxel size did not influence the evaluation of isthmuses in mandibular molars. The choice of the most appropriate protocol will depend on each clinical situation’ particularities.