Objective To compare the clinical effects of the two methods of intruding overerupted molars by micro-screws. Methods 21 overerupted molars were selected and ramdomly divided into group A and group B. Group A was implanted with one microscrew anchorage at the side of the buccolingual tongue, and the force was produced by the ten-sion spring. Group B was implanted with two microscrews combined with nickel - titanium fragments to lower the mo-lars. The distances, velocities and microscrew anchorage failure rates were measured and compared between the two groups. Results Two methods can achieve significant depressing effect, however, the failure rate of micro-screws was different in the two methods. The failure rates of group A and group B were 27.3%and 5.0%, respectively. The average speed of group A was 0.37 mm/month, and group B was 0.33 mm/month. Conclusion Both microscrew anchorage methods can effectively intrude overerupted upper molars. The speed of intrusion with microscrews directly is faster than NiTi Segmental arch and microscrews, but the implant failure of microscrews is higher.%目的 比较两种微螺钉支抗压低上颌伸长磨牙方法的临床效果.方法 将21颗伸长的上颌磨牙随机分为A、B两组,A组在被压低牙的颊腭侧各植入一颗微螺钉支抗,拉簧加力进行压低;B组在被压低牙的近中邻牙区颊腭侧各植入一颗微螺钉联合镍钛片段弓压低磨牙.测量并比较两组压低牙齿移动的距离、速度和微螺钉支抗失败率.结果 两种方法都可以取得明显的压低效果,但是两组磨牙压低速度和微螺钉失败率不同,差异均有统计学意义(P<0.05).A组磨牙压低平均速度是0.37 mm/月,B组平均压低速度是0.33 mm/月,A组和B组失败率分别为27.3%和5.0%.结论 两种微螺钉支抗压低磨牙方法均能达到较好的临床效果,微螺钉直接压低法效率稍快,但失败率更高.
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