Missing teeth are congenitally missing, acquired trauma, tooth decay or periodontal disease and other various causes of tooth loss, missing a tooth or several teeth, or no teeth in the whole mouth, these situations belong to missing teeth. If a missing tooth is missing for a long time and not restored, the position of the missing tooth will slowly become smaller and smaller, mainly from the three-dimensional aspect. The teeth on both sides of the missing tooth will tilt toward the side of the missing tooth, and the opposite side of the missing tooth will elongate toward it, resulting in less and less space for the missing tooth. If the patient has a desire to set the tooth, the space of the missing tooth may be too small to be restored, and by this time the adjacent teeth will have shifted, which will not only be irreparable but will also cause some damage to the adjacent teeth.