Objective: The purpose of this study was to evaluate the potential benefit of an ultrasonic device in apical surgery on the outcome of treatment when comparing with conventional technique using a bur. Methods:A case-control study was used in a standardized treatment protocol. 98 patients were treatment with an ultrasonic device or with a bur for preparation. One year after treatment the results were sorted and numbered by another clinician. The results were evaluated by a third dentist who was blinded for the therapy. Results:The overall success rate in the ultrasonic group was 90.0% and in the group treated with a bur 82.8%(P > 0.05). In premolars,the difference in success rate was 84.6% in ultrasonic group and 70.8% in conventional group(P > 0.05). Conclusion:The use of an ultrasonic device in apical surgery improved the outcome of treatment. Ultrasonic preparation could get better cannel obturation than conventional technique.