Objectives: The aim of this study was to verify whether there is a difference in the in vivo performance characteristics of CBCT and periapical radiography (PR) in assessing the apical extension of root canal obturation (RCO) and to evaluate the ability of CBCT in void detection using microsurgical findings as validation.
Methods: This study included 323 tooth roots that required surgical treatment and for which pre-existing periapical radiographs and CBCT images were available. Three calibrated observers individually analyzed the periapical radiographs, CBCT images and photomicrographs of each root. Performance characteristics of CBCT and PR were compared in terms of their evaluation of the apical extension of the RCOs. The ability of CBCT to detect voids in the RCOs was evaluated using microsurgical findings as validation. Kappa values were used for intraobserver/interobserver agreement.
Results: Perfect intraobserver/interobserver agreement (1.0) was achieved when using photomicrography. The two agreements of PR were superior to those of CBCT when CBCT was used to detect voids (p < 0.05). The sensitivity of CBCT [0.86, 95% confidence interval (CI) 0.76-0.93] was superior to that of PR (0.66, 95% CI 0.54-0.76) in detecting overextension (p < 0.005). CBCT showed a poor sensitivity (0.24, 95% CI 0.19-0.30) and specificity (0.67, 95% CI 0.54-0.78) in void detection.
Conclusions: CBCT was better than PR for evaluating the apical extension of RCOs. CBCT, with its poor sensitivity and specificity, might both overestimate and underestimate the proportion of voids in RCOs. CBCT was not suitable for evaluating the quality of RCOs.