Endodontics treats narrow root canals that are surrounded by hard tissue and difficult to see directly, and it is important to understand the three-dimensional positional relationship of the medullary cavity that extends inside the tooth. In this study, we used a surgical microscope camera with 4K (3840x2160) resolution to achieve alignment with a three-dimensional image virtually constructed on a computer-based on the patient's CT image. We evaluated the three-dimensional identification accuracy and processing speed and verified the future potential and problems as a precision root canal treatment support system.