the effect of intra-canal posts on diagnostic accuracy of cone beam computed tomography and digital radiography in detection of vertical root fractures

objective: diagnosis of vertical root fractures (vrfs) is critical in endodontics. cone beam computed tomography (cbct)  has significantly enhanced image quality compared to digital radiography (dr) and greatly aids the diagnosis of vrfs but, metal artifacts has remained as a problem in vrf detection.  this study evaluated the effect of intra canal posts on the diagnostic accuracy of cbct and dr for detection of vrfs. methods: in this experimental in vitro study eighty extracted human premolar teeth were cut at the cement-enamel junction .after root canal preparation, the casting posts were made. samples were randomly divided into 2 groups of 40 group one with induced fracture and group 2 as the control group. radiographs were taken for  all specimens with and without posts with both imaging systems. three observers assessed the presence or absence of vrf. accuracy of the two imaging systems and the effect of post on vrf detection were assessed, using two-way anova test and inter observer coefficient agreement was calculated. results: absolute diagnostic sensitivity and specificity of cbct and absolute sensitivity of dr in the group with intracanal posts were significantly lower than those in the group without posts (p=0.023, p=0.034 and p=0.034 respectively). absolute specificity of dr in the group with posts was significantly higher than that of the cbct (p=0.014). the absolute and complete specificity of cbct in the group without posts was significantly higher than those of dr (p=0.024, p=0.04). no statistically significant difference was found in inter observer agreement coefficient in presence or absence of posts or between the two imaging systems (p=0.119). conclusion: intra canal posts decreased the diagnostic accuracy of cbct and dr for detection of vrfs and this reduction was greater in cbct. however, absolute specificity of dr in the group with posts was significantly higher than that of the cbct, where as cbct images of teeth without posts still had higher diagnostic accuracy than dr.