Root canal treatment is a small oral surgery used to treat pulpal necrosis and infection. The specific operation process can be divided into three steps: preparation, sterilization and filling. 1. Root canal preparation: preoperative evaluation, pulp cavity preparation, and determination of working length should be carried out before preparation. Root canal preparation is based on the choice of instruments to prepare the root canal. 2. Root canal disinfection: Live pulp teeth can be disinfected once, while others need to be sealed, usually 2-4 times. 3. Root canal filling: filling is usually done when there are no self-conscious symptoms, no obvious percussion pain, no odor in the canal, no oozing, no acute infection, no need to wait until all the symptoms have disappeared, then filling can be done, and usually fill with cold dental adhesive with lateral pressure method. Root canal surgery is generally no obvious pain, do not need to be too nervous, the procedure just need to cooperate with the doctor operation.