目的：比较两种旋转镍钛系统Twisted File（TF）和ProTaper Universal（PU）预备根管的有效性和安全性。方法：收集离体磨牙样本20颗（62个根管），随机分成2组，分别使用TF和PU按照推荐程序预备根管至#25/0.08，记录预备时间（使用每支镍钛锉的累加时间）。利用立体显微镜在25倍放大下观察并记录两组牙齿预备前后根尖3 mm区域牙根表面裂纹，应用Micro-CT对预备前后根管形态进行扫描重建分析，比较两组根管预备时间以及根管中心偏移等三维形态变化。结果：TF组每根管的平均预备时间为（0.53±0.14） min，明显短于PU组（2.06±0.39） min（P<0.05）。在根管中段，两实验组根管中心偏移量分别为：TF组（0.070±0.056） mm、PU组（0.097±0.084） mm，差异具有统计学意义（P<0.05）。TF组和PU组在预备过程中均未发生器械折断；根管预备完成后，3D表面重建分析以及立体显微镜下观察，两组均未见牙根裂纹的产生。 结论：与PU相比，TF镍钛系统预备磨牙根管所用时间短，效率高；TF根管中段的中心偏移小，成形效果好，优于PU。

Objective： To evaluate the efficacy and security of two type of rotary nickel titanium system (Twisted File and ProTaper Universal) for root canal preparation based on micro-computed tomography(micro-CT).Methods: Twenty extracted molars (including 62 canals) were divided into two experimental groups and were respectively instrumented using Twisted File rotary nickel titanium system (TF) and ProTaper Universal rotary nickel titanium system (PU) to #25/0.08 following recommended protocol. Time for root canal instrumentation (accumulation of time for every single file) was recorded. The 0-3 mm root surface from apex was observed under an optical stereomicroscope at 25×magnification. The presence of crack line was noted. The root canals were scanned with micro-CT before and after root canal preparation. Threedimensional shape images of canals were reconstructed, calculated and evaluated. The amount of canal central transportation of the two groups was calculated and compared.Results:The shorter preparation time ［(0.53±0.14) min］ was observed in TF group, while the preparation time of PU group was (2.06±0.39) min (P<0.05). In mid-root level, TF group shaping resulted in less canal center transportation than PU group ［(0.070±0.056) mm vs. (0.097±0.084) mm, P<0.05］. No instrument separation was observed in both the groups. Cracks were not found in both the groups either based in micro-CT images or observation under an optical stereomicroscope at 25× magnification.  Conclusion:Compared with ProTaper Universal, Twisted File took less time in root canal preparation and exhibited better shaping ability, and less canal transportation.