Dental CT as a dedicated CT of human maxillofacial is widely used in clinical procedures including preoperative evaluation of impacted teeth in bone, dental implants, diagnosis of temporomandibular joint disease, jaw cysts and tumors, orthodontics, and teeth marrow disease, etc. Although there are some Dental CT machines abroad, they are expensive and there are some shortcomings in their functions and technical indexes. Dental CT has the following advantages: as no destruction, high resolution, no image overlapping, no image distortion and low dose. By virtue of high resolution and no image distortion, this CT system can be widely applied in a number of dental treatments such as filling, tooth-planting, periodontal disease, dental surgery etc.