Endodontic treatment for pulpitis has no side effects, just complications. Pulpitis is treated due to inflammation of the pulp, and this inflammation is an irreversible lesion, so pulp treatment is performed, which means that the pulp is removed. The most used treatment nowadays is still root canal therapy. The main complication of root canal treatment is acute inflammation. Root canal tooth pain is mainly due to the fact that during the treatment, opening the pulp will destroy the blood vessels in the pulp cavity and the blood vessels will be filled with blood resulting in tooth pain, and the tooth may also crumble during root canal treatment, which also causes tooth pain. When pain occurs after root canal treatment, it is necessary to review and determine the main cause of tooth pain. If the pain is from the tooth itself, you should observe whether it is a problem of root canal treatment, if the pain is caused by unsuccessful root canal treatment, you should find out the reason of unsuccessful root canal treatment, such as pain caused by unsuitable root canal, or the tooth may have new cracks or inflammation, and inflammation not cleared,; also There may be periodontal lesions. Find out the reason for the failure of root canal treatment and adjust the treatment so that the pain will be relieved. Toothache after root canal treatment is mainly caused by inflammation and root canal treatment failure. If toothache occurs, follow up promptly.