Three-dimensional analysis of root canal curvature in maxillary premolars using CBCT images.

Understanding the root canal system is essential for success in root canal therapy (RCT). Two-dimensional (2D) images, such as panoramic and periapical radiographs, provide limited information on the superimposition of structures. This study aimed to analyze the root canal of maxillary premolars on CBCT using a three-dimensional (3D) canal navigation tool. A virtual 3D root canal was created by connecting the root canal center points of 400 premolars, and the canal type (single or double) was classified, and the most curved point (MCP) was designated. The curvature at the MCP in each canal was automatically calculated using the radius (R) value of the tangent circle. A total of 99.5% of first and 88.0% of second premolars had double canals of buccal and palatal. The mean R value of the MCPs was 1.50 mm for first and 1.58 mm for second premolars. Most MCPs were located in the apical part, but 12.1-35.2% of those in double canals were located in the middle or coronal part. 3D analysis tools on CBCT provide accurate information on the root canal system including the canal curvature, thereby increasing the success rate of RCT.