Objective To evaluate the therapeutic effect of teeth with large periapical lesions followed apical surgery. Methods 59 patients（59 periapical lesions, 91 teeth） with large periapical lesions ranging in size from 6 mm to 21 mm in diameter were included in this study. All teeth were treated by root canal therapy and apical surgery, and the surgical procedure was completed with microsurgical technology and ultrasonic root -end preparation. The outcomes were evaluated clinically and radiographically at 1, 3, 6, 9, 12 and 24-month intervals, and the various factors which may affect the success rate were analyzed statistically. Results 52 cases（88.1%） of 59 patients were considered success, 6 cases（10.2%） were considered failure, and 1 case（1.7%） was considered in progress. The success rate of elderly patients group（63.6%） was significantly lower than that of the youth group（87.5%） and middle-aged group（95.0%）（P=0.037；P=0.017）. The success rate of molar group（75.0%） was significantly lower than that of the anterior group（92.6%） and the premolar group（90.0%）（P=0.041, P=0.047）；however, there was no significant difference in the gender, the number of teeth invaded in lesions, the size of periapical lesion（P>0.05）. Conclusion It is an effective therapy for the teeth with large periapical lesions by apical surgery after root canal treatment.
