Killing the nerve and then stuffing it with cotton will hurt for about three days, depending on the individual. Cotton after killing the nerve can relieve the excessive pressure inside the pulp cavity and reduce the pain. In addition, there is a disinfectant drug inside the cotton, and after disinfection, you can proceed to the subsequent root canal filling. The pain will subside in about three days after the cotton is inserted after the nerve is killed, or the pain will stop, depending on the patient’s condition. If the pain does not improve, it may be affected by inflammation, need to re-open, anti-inflammatory and then sealing medicine, serious inflammation needs to be drained first. After killing the nerve must pay attention to, do not use the teeth to eat hard, cold and irritating food, to ensure that the mouth is clean, must rinse after meals, morning and evening to do the correct brushing. Diet should pay attention to nutritional balance, light. If the patient kills the dental nerve after stuffing cotton, there is a long time pain and other abnormalities, should promptly go to the hospital stomatology department.