Toothache after one year of root canal treatment is generally considered to appear after root canal treatment disease, it is the situation of periapical inflammation again after root canal treatment, the possible reasons are: 1, the root canal treatment is not perfect when the root canal treatment, there are missed root canals or there are side branch root canals and other possible. 2, root canal treatment is perfect, but the inflammation of the patient’s root tip has not completely subsided, and after one year the inflammation again appears, need The diagnosis is confirmed by x-ray examination. If the disease occurs after root canal treatment, root canal retreatment can be considered, but root canal retreatment is more difficult, and if the affected tooth has no retention value, the tooth can also be considered to be extracted.