Toothache one year after root canal treatment may be caused by the incomplete treatment of the first root canal or the reoccurrence of inflammation at the root tip. Patients usually need to undergo a new root canal treatment and take anti-inflammatory and pain-relieving medication to treat the toothache. Root canal treatment is mainly used to treat endodontics or periapical disease, removing infected material from the pulp cavity to relieve pulpal inflammation. If the removal is incomplete, it may re-initiate pulpal inflammation, resulting in a recurrence of the toothache after one year. It is recommended that the patient undergo a new root canal for treatment. If the inflammation of the apical root tissue is not well controlled after using root canal treatment, it may also cause the tooth pain after one year. The patient can visit the hospital to find out the cause of the disease, and can choose to re-treat the root canal or perform apical surgery. Significant pain can be prescribed oral anti-inflammatory painkillers, such as metronidazole, ibuprofen and so on. If the patient in the root canal treatment after a year of toothache, should go to the regular dental hospital in time for examination, identify the cause of the disease under the guidance of professional doctors for targeted treatment.