With the progress of science and technology, the medical field of examination means are also becoming increasingly mature, CBCT is after 2000, because of its small ionizing radiation (equivalent to panoramic film 4 times, less than the traditional CT nearly 50 times), high precision, display three-dimensional spatial structure and widely used in orthodontics and implants to guide the effective clinical work. Luo Ying, Department of Orthodontics, Hangzhou Stomatological Hospital The role of CBCT in orthodontics mainly lies in the following aspects: 1. Determination of the location of pathological lesions: ambiguous teeth (transposition, obstruction, malocclusion, multiple teeth) maxillary sinus cysts, polyps, apical inflammation, etc. The traditional two-dimensional panoramic film cannot accurately give the position of the buried tooth and the proximity to the adjacent teeth due to overlapping shadows, artifacts, magnification, distortion and deformation, and whether it has caused root resorption of adjacent teeth. 2. Evaluation of TMJ: The ratio of the upper three gaps between the anterior and posterior joints, the morphology of the condyles, and whether there is resorption, abrasion, or even trauma. 3. Evaluation of inter-root distance, root morphology, thickness of cortical bone, density of cancellous bone and position of maxillary sinus and sinus floor morphology in the area of implant placement to guide the site, height and angle of implant placement to ensure the safety and stability of implant placement. Of course, CBCT can also be used to measure the airway of snoring patients and determine the specific site of blockage; determine the orthodontic plan (based on the thickness of the alveolar bone in the upper and lower incisors, estimate the distance of inward or forward movement; evaluate the effect after arch expansion; evaluate the changes before and after orthodontic treatment in 3D; plan and simulate orthognathic surgery, etc. Looking ahead, the combination with 3D printing technology will bring our treatment level into a new world. In the future, the combination with 3D printing technology will bring our treatment level into a new world.