1. Confirm whether the wound is healing well at the site of the missing tooth (3 months after extraction), and whether there are any remaining roots and fragments. Protruding bone tips, scar tissue, etc. If they exist, oral surgery disposal is required before the teeth can be set. 2. Regarding the examination of the remaining teeth, especially the teeth in the adjacent parts of the missing teeth, whether the position is normal, whether the occlusal condition is good, whether there is defect and caries in the teeth, whether the periodontal tissues are healthy, the oral hygiene condition, tartar and soft tartar condition. If the above elements are present, dental implants are required to be placed at an optional date after treatment by endodontics.