3Oginni A, Udoye C I.Endodontic flare-ups: comparison of incidence between single and multiple visits procedures in patients attending a Nigerian teaching hospital[J].Int Endod J, 2004, 37(1): 70-82.
4Smith C S, Setchell D J, Harty F J.Factors influencing the success of conventional root canal therapy-a five-year retrospective study[J].Int Endod J, 1993, 26(6): 321-333.