It is normal to experience bite pain during or after the completion of root canal treatment. Generally, the bite pain will gradually disappear within a period of time after the root canal is completed. Bite pain during root canal treatment is usually seen when the root canal, pulp or periodontium of the tooth has been infected more seriously before the treatment. During the root canal treatment, the root canal will be repeatedly flushed and the canal will be prepared with manual or nickel-titanium instruments. Bite pain occurs during root canal treatment and even for a period of time after root canal treatment. When the infected material in the root canal is completely removed and the source of infection is cleared, the inflammation in the apical area will be metabolized and absorbed by the organism gradually, and the pain will disappear when the inflammation is metabolized and absorbed.