If there is pain and discomfort within a short period of time after killing the nerve, most of them are normal; if there is repeated pain and discomfort for a long period of time, most of them are abnormal and may need to be re-treated. 1. Pain and discomfort within a short period of time: if there is pain and discomfort within 2-3 days after killing the nerve, and then gradually relieved and disappeared, most of them are normal, because if the inflammation of the teeth is heavy, the postoperative recovery needs a process. 2. Pain and discomfort after a long period of time: If there is still pain and discomfort or no obvious relief for a few months after killing the nerve, or no pain at the end of the treatment, and then there is pain and discomfort after a few years, most of the time it is abnormal, which may be related to the incomplete endodontic treatment, and the tooth splitting caused by the tooth not being restored in time after the treatment, and so on, and it is recommended to actively follow up for a second treatment or extraction, and so on.