[摘要]目的 了解被动逐步后退法清理根管的效果。方法 分别应用被动逐步后退法、逐步后退法、逐步深入法对人恒磨牙近中颊根管进行预备，纵向劈开牙根，扫描电镜下观察根管内壁冠1/3、中1/3及根尖1/3牙本质碎屑和玷污层的形成情况。结果 3种方法对根管清理能力差异无显著性( F=2.98～3.19，P >0.05)。结论被动逐步后退法操作费时费力，无显著优越性。

    [关键词] 根管制备;被动逐步后退法;牙髓腔

    EFFECTIVENESS OF PASSIVE STEP-BACK TECHNIQUE FOR CLEANING THE FINE CURVED CANAL OF POSTERIOR TEETH

    YUAN CHANG-QING，ZHONG DE-YU， DENG JING

    (Department of Stomatology， The Affiliated Hospital of Qingdao Uni-versity Medical College， Qingdao 266003， China)

    [ABSTRACT]ObjectiveTo study the effectiveness of passive step-back technique for cleaning the fine curved canals of pos-terior teeth. MethodsMesiobuccal root canals of human molar teeth were prepared by passive step-back technique， step-down technique or step-back technique. The roots were cracked longitudinally ......