Objective:To compare the effectiveness of the ProTaper Universal, R-Endo retreatment files and a Hedstrom manual technique in the removal of gutta- percha during retreatment. Methods: 60 single- rooted straight mandibular premolars were selected. The root canals of all cases were shaped by Nickel-Titanium rotary instruments Hero 642, and obturated with lateral condensation technique. Then all cases were randomly divided into 3 groups(n =20) and prepared with a Hedstrom manual technique, ProTaper Universal and R-Endo retreatment files respectively. Eucalyptol was used as a solvent in the treatment. For all roots, the following data were recorded: procedural errors and time of retreatment. Bucco-lingual and proximal radiographs of the roots were taken and the percentage area of the remaining material was calculated by dividing the area of remaining filling material by the area of canal wall. Data were statistically analysed with Kruskal-Wallis and Mann-Whitney U tests(P =0. 05). Results: None of the techniques completely removed the root filling materials. The remaining filling material was significantly less after manual instrumentation than R-Endo or ProTaper instrumentation(P<0. 05) . The ProTaper and R-Endo retreatment files had a positive impact in reducing the time for retreatment( P < 0. 05 ). Conclusion; All tested instruments can not completely remove the filling material inside the root canal. ProTaper and R-Endo rotary instruments work faster than manual instruments.%目的:比较Protaper Universal、R-Endo镍钛根管再治疗器械和手用H锉等3种器械在再治疗根管中对牙胶的清理能力.方法:选取60个单根管的离体下颌前磨牙,截去牙冠部统一工作长度,使用Her0 642镍钛器械预备至30#,侧方加压法完成牙胶尖和糊剂充填.样本随机分为3组,分别使用手用H锉,Protaper Universal和R- Endo清理根管内充填材料,记录操作过程引起的堵塞、台阶、穿孔等并发问题以及操作时间.随后从颊舌和近远中2个角度拍数码X线照片,使用图像分析软件分析根管壁的清洁度.结果:所有样本均有充填物残留,手用器械组管壁充填物的残留量明显低于机用镍钛2组(P＜0.05),ProTaper Universal和R- Endo两者之间差异无显著性.和手用H锉比较,Protaper Universal和R- Endo均可减少再治疗的时间(P＜0.05).结论:所有器械均会残留根管充填物,机用镍钛器械残留的充填物较多,但可以明显减少操作时间.
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