Half of the back teeth are lost, which is a common symptom in clinical practice. It is recommended that the patient should have an examination in a professional dental institution, and dental radiographs should be taken to check the specific remaining condition of the tooth, and in most cases, the tooth can be retained. After the cleaning, the tooth can be made into a form that can bear the resistance shape, and then the root canal treatment can be carried out systematically for the pulp cavity of the tooth, and after the root canal treatment is completed, the pile crown can be made to restore the tooth, so that this tooth can serve for a longer time.