Objective To evaluate the outcome of endodontic microsurgery in 54 cases with persistent apical periodontitis. Methods All surgical procedures were performed under a dental operating microscope after root canal treatment. Surgical procedures included periapical curettage, root-end resection, retropreparation with ultrasonic microtips, and root -end filling with mineral trioxide aggregate（MTA）. Healing was monitored clinically and radiographically. Results One year later, 31（57.41%） cases were cured, 19（35.19%） cases were improved, 4（7.41%） cases were failure. There were no statistical difference between sex, age, tooth location, size of the lesion and pathological features（P>0.05）. Conclusion The outcome of the present study indicates that endodontic microsurgery may result in a predictable treatment outcome in teeth with persistent periradicular lesions.
