Teeth can be extracted in the following cases: 1, teeth with extensive and severe caries that cannot be repaired; 2, teeth with extensive resorption and destruction around the root, which cannot be cured by root canal therapy, apicoectomy, etc.; 3, teeth suffering from periodontal disease, with most of the alveolar bone resorbed and the degree of tooth looseness exceeding III; 4, teeth with longitudinal folding of the root, which leads to recurrent fistulae and infections of buccal gingiva When there are retained milk teeth in children, which affects the eruption of permanent teeth; 6. Orthodontic treatment requires the removal of wisdom teeth or the first and second premolar teeth to obtain orthodontic space; 7. Multiple teeth and blocked teeth; 8. Some teeth undergo intrapulpal resorption, which is easy to fracture, and should be extracted at the earliest possible time.