Methods: In this in vitro experimental study, mesial root canals of 97 extracted human mandibular molar teeth were prepared. Distal wall of the mesiolingual canals were thinned in the danger zone. Then 51 teeth were randomly perforated. Before and after obturation, PR (3 horizontal angulations: 20 degree mesial, straight and 20 degree distal) and CBCT were performed and evaluated by two observers. Chi square and Fisher Exact tests were used for statistical analysis, with significance level set at P=0.05.
Results: In the absence of root filling, sensitivity, specificity, and accuracy of CBCT was superior to PR (P<0.05). In the presence of root filling, the sensitivity of PR was significantly higher (P<0.05), although specificity and accuracy were not significantly different. After root canal obturation, the sensitivity, specificity, and accuracy of CBCT were significantly dropped (P<0.05). However, the sensitivity, specificity and accuracy of PR were significantly increased (P<0.05).
Conclusions: Under the conditions of this in vitro study, in the absence of root filling, CBCT was superior to PR. In the presence of root filling, PR was more sensitive. The presence of root filling reduced the ability of CBCT and increased the ability of PR in detecting strip root perforations.