目的:比较2种不同类型机用镍钛根管预备器械Mtwo、K3的根管成形效果。方法:选择36个离体上颌第一磨牙的近中颊侧根管,根据其弯曲度分成A(弯曲度≥20°)、B(弯曲度<20°)2组,每组再随机分成2个亚组,分别采用镍钛锉Mtwo和K3进行根管预备。预备前后,分别向根管内注入造影剂并拍摄数字X线片,利用合作研制的计算机图像分析软件生成预备前根管几何中心线并投影至预备后根管,测定根管偏移量(几何中心线偏移量)及根管弯曲度的变化。所有数据用SPSS11.0软件包进行统计学分析。结果:各组样本经t检验分析,根管弯曲度≥20°时,根管弯曲起始处的根管偏移量Mtwo组显著小于K3组(P<0.05);根管弯曲度减小量Mtwo组显著小于K3组(P<0.05)。根管弯曲度<20°时,Mtwo、K3组间根管偏移量及根管弯曲度减小量均无显著性差异(P>0.05)。结论:Mtwo、K3根管预备时均能良好维持原始根管的中心位置;预备弯曲度大于20°根管时,Mtwo可更好维持原始根管弯曲度及走向。 OBJECTIVE: To compare the root canal forming effects of Mtwo and K3 for two different types of NiTi equipment. Methods: The 36 proximal maxillary first molars were selected and divided into two groups according to the degree of curvature: A (degree of curvature ≥20 °) and B (degree of curvature <20 °), and each group was randomly divided into two groups A subgroup, respectively, using nickel titanium file Mtwo and K3 for root canal preparation. Before and after the preparation, respectively, into the root canal injection of contrast media and digital X-ray film, the use of computer software developed by the collaborative computer image analysis software to generate the geometric center line before preparation and projection to the preparation of post-root canal, determination of root canal offset Centerline offset) and changes in root canal curvature. All data were statistically analyzed using SPSS 11.0 software package. Results: The results of t-test showed that the root canal deviation Mtwo at the beginning of root canal bending was significantly lower than that of K3 at the bending of root canal ≥20 ° (P <0.05) Mtwo group was significantly smaller than K3 group (P <0.05). There was no significant difference in root canal offset and root canal curvature reduction between Mtwo and K3 group (P> 0.05) when root canal curvature was less than 20 °. Conclusion: Mtwo and K3 could well maintain the original position of the root canal in the preparation of root canal. Mtwo could maintain the curvature and orientation of the root canal more than 20 °.