Tooth pain after the second dressing change of root canal treatment may require removing the medication, treating again, observing for a period of time and waiting for self-healing, or extracting the affected tooth, etc. It is recommended to go to the hospital for timely examination and treatment. 1. If the pain is caused by too much pressure from the medication during the second dressing change, the medication can be rinsed out and resealed to relieve the pain. 2. If there is persistent pain and spontaneous pain, it may be caused by missing root canals or other affected teeth, and the tooth needs to be retreated or other affected teeth need to be retreated. 3. During root canal treatment, there will be swelling and discomfort, usually two or three days after the recovery, this situation can wait for self-healing. 4. If the tooth splits and causes pain after root canal treatment, the tooth needs to be extracted.