If the decayed part has touched the nerve of the tooth, or if there is pulpitis, periapical inflammation or pulp necrosis, the filling alone cannot relieve the symptoms and root canal treatment is needed. The filling usually needs to remove the food residue and decayed tooth tissue in the cavity, and then choose different materials to fill the cavity, commonly used filling materials include silver amalgam, composite resin, etc., which can be chosen under the guidance of doctor according to personal economic situation. In some patients, the decayed part of the tooth does not touch the nerve, but the distance is close, in order to protect the tooth, it is also necessary to choose suitable materials for cushion restoration, and then carry out cavity filling. Some patients need local anesthesia for root canal treatment, then remove the decayed dentin and open the pulp cavity to take out the infected or necrotic pulp, disinfect it and use specific materials for filling. The treated tooth is prone to fracture, so crowns are often chosen to maintain the normal function of the tooth. In addition, if a cavity occurs along with severe loosening of the tooth, it may no longer be treatable and requires extraction. Patients are advised to visit the dentistry department of the hospital in a timely manner, conduct the corresponding examination and choose the appropriate treatment plan under the guidance of the doctor to avoid delaying the treatment and causing serious consequences.