In the diagnosis and treatment of oral diseases, imaging examination is a more important auxiliary method. Among them, the application of digital X-ray examination is the most common. However, because the image information provided by this technology is a two-dimensional model, it is difficult to obtain a comprehensive image, so there is a missed diagnosis. With the development of imaging technology, cone-beam CT (CBCT) is widely used in the diagnosis and treatment of oral diseases. This is a non-invasive imaging examination. The diagnosis effect is achieved by cone-beam computed tomography or volume tomography. It has less radiation and low cost. Clear imaging and high spatial resolution. This study compared the diagnostic effect of cone-beam CT and traditional X-ray examination in diseases related to oral medicine to observe the diagnostic superiority of cone-beam CT. In this study, we can know that 30 patients with periapical periodontal disease have been treated by this technique, and the detection accuracy rate is 100.00%. The damage of the apical root of the patient’s tooth is completely displayed in the image. The measurement results of the bone defect around the tooth are accurate and space and the location image is presented in front of the doctor, so the detection accuracy of this technology is high. The study found that cone beam CT is effective in the diagnosis and treatment of diseases in oral medicine, and can clearly show the three-dimensional structure of oral tissue, which is convenient for physicians to observe the shape of the disease and improve the accuracy of disease diagnosis.