[Accuracy assessment of cone beam computed tomography-reconstructed three-dimensional anatomical models of primary teeth using micro-CT].

Objective: To validate the accuracy of three-dimensional anatomical models reconstructed from cone beam computed tomography (CBCT) using micro-CT as the gold standard, and to evaluate the feasibility of performing anatomical analyses on such models. Methods: A total of 13 isolated primary teeth with intact roots were collected, including 5 anterior teeth and 8 molars, with a total of 34 root canals. The teeth were extracted from children aged 3-9 years who visited Peking University Hospital of Stomatology between January 2019 and April 2022 due to trauma or periapical disease, and were then scanned by micro-CT (with a voxel size of 0.018 mm) and CBCT (with a voxel size of 0.125 mm), respectively. Using a threshold-based semi-automated region segmentation method, anatomical models of these isolated teeth were reconstructed from the two CTs. Subsequently, the two CT reconstructed models were registered based on the iterative closest point algorithm, then the deviation analysis was performed. The key anatomical parameters were measured on the micro-CT and CBCT models, respectively, and the difference was calculated. Results: The CBCT reconstruction model were relatively accurate in the hard tissue morphology, and 97.1% (33/34) of the root canals were identified accurately. When it comes to the deviation analysis, the average distance between the matched points on the CBCT reconstruction models and the micro-CT models was (0.01±0.03) mm for the hard tissue, and (0.00±0.03) mm for the pulp chambers and canals, which did not affect clinical observation. The hard tissue and root canal length of CBCT models were both smaller than that of micro-CT models (P<0.05), with a 95% limits of agreement of (-0.70, 0.14) mm for the hard tissue, and a 95% limits of agreement of (-1.93, 1.00) mm for the pulp chambers and canals. The impact of these differences on clinical operations were all within the acceptable range. Conclusions: Using micro-CT as a validate standard, CBCT with a voxel size of 0.125 mm was proved to be an effective tool for the reconstruction of deciduous teeth. Therefore, the reconstructed models was appropriate for studying deciduous teeth anatomy.