Accuracy of CBCT for volumetric measurement of simulated periapical lesions

Aim To compare the accuracy of cone beam computed tomography (CBCT) and micro-computed tomography (CT) when measuring the volume of bone cavities. Methodology Ten irregular-shaped cavities of varying dimensions were created in bovine bone specimens using a rotary diamond bur. The samples were then scanned using the Accuitomo 3D (R) CBCT scanner. The scanned information was converted to the Digital Imaging and Communication in Medicine (DICOM) format ready for analysis. Once formatted, 10 trained and calibrated examiners segmented the scans and measured the volumes of the lesions. Intra/interexaminer agreement was assessed by each examiner re-segmenting each scan after a 2-week interval. Micro-CT scans were analysed by a single examiner. To achieve a physical reading of the artificially created cavities, replicas were created using dimensionally stable silicone impression material. After measuring the mass of each impression sample, the volume was calculated by dividing the mass of each sample by the density of the set impression material. Further corroboration of these measurements was obtained by employing Archimedes' principle to measure the volume of each impression sample. Intraclass correlation was used to assess agreement. Results Both CBCT (mean volume: 175.9mm3) and CT (mean volume: 163.1mm3) showed a high degree of agreement (intraclass correlation coefficient >0.9) when compared to both weighed and Archimedes' principle' measurements (mean volume: 177.7 and 182.6mm3, respectively). Conclusion Cone beam computed tomography is an accurate means of measuring volume of artificially created bone cavities in an ex vivo model. This may provide a valuable tool for monitoring the healing rate of apical periodontitis; further investigations are warranted.