Pain after root canal treatment sealing may be caused by instrument irritation, use of sealing medication, pulpitis, etc. The causes are different and the treatments are different, which can be dealt with by symptomatic treatment, replacing medication and cleaning the pulp. 1. Instrument irritation: During root canal treatment, the instruments used cause stinging pain to the tissues around the root of the tooth. This is very common and does not require any special treatment, usually the pain will disappear automatically after 2-7 days. The patient should try not to chew food with the bad tooth so as not to aggravate the pain. 2. Sealing medication: The toothache may also be caused by the medication used to seal the tooth, which can be replaced with mild pulp cushioning materials, such as zinc oxide clove oil salve, calcium hydroxide to seal the medication. 3. Residual pulpitis: it may be the residual pulp that causes inflammation and pain when sealing medication, the patient needs to be operated by the dentist to re-execute the root canal treatment to clean up the residual pulp. Root canal treatment after sealing pain, it is recommended that the patient timely hospitalization review, to take appropriate treatment measures to avoid further aggravation of the condition.