Root canal treatment may cause the patient to experience weakness in chewing, tooth pain, residual pulpitis and other sequelae. 1. Weakness in chewing: after root canal treatment, if the patient’s apical periodontitis has not completely disappeared and the periodontium has not completely recovered, weakness in chewing may occur. 2. Tooth pain: after root canal treatment, tooth pain may occur due to instrument stimulation. Meanwhile, if the root canal treatment is not complete, tooth pain may also occur. 3. Residual pulpitis: Residual pulpitis is the inflammation of a small amount of root pulp left after root canal treatment, which may cause pain and bite discomfort in the affected tooth. When patients experience any discomfort after root canal treatment, it is recommended that they seek prompt medical attention and go to the dentist for diagnosis and reasonable treatment by a professional doctor.