Objective To study the root resorption caused by edgewise appliance combined with flat bite plate treatment. Methods 65 patients with edgewise technique and flat bite plate treatment were chosen. All patients were taken panoramic radiograph before flat bite plate treatment, immediately after flat bite plate treatment and 6 months after flat bite plate treatment. Root resorption grade of mandibular permanent incisors were analyzed. Results There were statistical difference in the root resorption grade of three groups（P0.05）. Conclusion Flat bite plate can cause root resorption of mandibular permanent incisors, but the root resorption is slight.
