The number of times root canal treatment is generally performed clinically is uncertain and depends on the specific situation of the patient’s affected tooth, in general, it can be done 1-4 times. If the patient has a tooth with irreducible pulpitis, a one-time root canal treatment can be taken, but for advanced stages of irreducible pulpitis, the success rate of one treatment may not be as high as the success rate of 2-3 treatments because the pulp has been infected to the root pulp, and the treatment time should be extended at this time. However, for patients with periapical inflammation or even apical abscesses, 3-4 root canals are needed at this time because the apical inflammation is more pronounced and the periapical tissues may have pus conditions. The first time requires root canal opening treatment after root canal preparation, the second time after root canal opening should be considered root canal disinfection depending on the degree of pus, and the third time after apical inflammation is basically controlled before root canal filling is done. Therefore, the number of root canal treatment depends on the condition of the affected tooth and cannot be generalized.