Root canal treatment generally need to go three times, the nerve necrosis need to go twice, individual inflammation heavy need to go a few more times to change the medicine, root canal treatment need to go to do restorations, probably need to be about two times, it is recommended to go to the hospital to check the condition of the tooth specifically. 1. Generally speaking, root canal treatment requires the first time to kill the nerve; the second time to take the nerve to remove the infected material in the root canal, and put anti-inflammatory and antibacterial drugs; the third time to fill the root canal with alternative materials such as dental adhesive, and the treatment is completed. 2. If the affected tooth is already necrotic or the nerve can be removed under anesthesia, then two treatments are needed. 3. If the affected tooth is heavily inflamed with recurrent pus, the number of changes may need to be increased. 4. After root canal treatment, it is usually recommended to do crown restoration and other protection of the tooth, usually the first time you need to prepare the tooth and take the model; the second time to wear the tooth.