diagnostic accuracy of different resolutions of cone beam computed tomography imaging system for detection of vertical root fractures in presence of casting posts

objective: the diagnosis of vertical root fracture (vrf) in endodontically treated teeth is a clinical challenge due to lack of specific clinical and radiographic signs. although radiographic evaluation such as cbct is helpful, intracanal posts can produce artifacts and may impair the quality of cbct scans. this study aimed to compare the diagnostic accuracy of different resolutions of cbct in detection of vrf in roots with casting post.   methods: eighty extracted human premolars were under went routine endodontic procedure and cast posts were subsequently prepared. the teeth were randomly divided into two groups. the fracture lines were induced by an instron machine in test group, while the teeth in control group had no fracture. the teeth were scanned by cbct with two voxel resolution protocols (0.15mm and 0.2mm). three observers assessed the scans for presence of vrf on a 5-point scale. diagnostic accuracy indices were estimated and the difference were analyzed with the mann-whitney test (p<0.05).   results: probabilistic sensitivity for 0.15mm and 0.2mm resolution was 59.16 (5.2) and 46.66 (16.64), respectively. furthermore, probabilistic specificity for 0.15mm resolution was 56.16 (15.21) and for 0.2mm was 61.66 (8.77).there were no statistical differences between different resolutions in all diagnostic values including sensitivity, specificity, positive and negative predictive values (p>0.05).   conclusion: diagnostic ability of cbct in presence of casting posts was not influenced by system resolution. according to alara principle, 0.2mm voxel resolution protocol is recommended in these cases.