中文摘要：

目的比较4种机用镍钛器械预备S形树脂模拟根管的成形能力，为临床应用提供实验依据。方法将40个S形树脂模拟根管按随机数字表法分为4组，每组10个，分别使用Reciproc （A组）、WaveOne（B组）、Mtwo（C组）和ProTaper（D组）进行根管预备，记录预备时间，测量预备后根管工作长度，扫描仪获取预备前后根管图像，使用Photoshop 和ImageJ 软件进行图像重叠并分别测量预备后根管冠方弯曲角度和根方弯曲角度的变化值，从距根尖孔1 mm处开始，每隔1 mm测量根管内外侧壁树脂去除量，共10个测量点，各观测点弯曲外侧树脂去除量减去内侧树脂去除量所得差值即为器械的中心定位能力。以单因素方差分析和Student-Newman-Keuls检验进行统计学分析，检验水准为双侧α＝0.05。结果 A、B、C、D组器械预备时间分别为（42.1±2.7）、（41.5±3.2）、（62.7±2.8）及（62.8±5.2） s，A、B组的根管预备时间均显著短于C、D组（P＜0.05）。4种器械预备后根管工作长度变化值差异无统计学意义（ P ＞0.05）。 A、B、D 组根管冠方弯曲角度变化值[分别为（4.69±0.63）°、（4.15±0.89）°及（4.13±0.59）°]均显著小于C组[（5.26±0.70）°]（P＜0.05），4种器械根管根方弯曲角度变化值差异无统计学意义（ P＞0.05）。距根尖孔2 mm位点，A、B和D组的中心定位能力[分别为（-0.242±0.042）、（-0.191±0.077）、（-0.272±0.046） mm]显著优于C组[（-0.343±0.057） mm]（P＜0.05）；距根尖孔3 mm和4 mm位点，A、B组的中心定位能力均显著优于C、D组（P＜0.05）；距根尖孔5 mm处，D组的中心定位能力显著优于A、B组（P＜0.05）。结论 A锉和B锉可以快速有效地预备根管，且能较好地保持S形树脂根管的原始形态，在根管根方弯曲部分具有较好的中心定位能力。

英文摘要：

Objective To evaluate the shaping ability of Reciproc ,WaveOne,Mtwo and ProTaper instruments in simulated S-shaped root canals.Methods A total of 40 simulated S-shaped resin blocks were divided randomly into four groups,each group was prepared with Reciproc （group A）,WaveOne（group B）, Mtwo（group C） and ProTaper（group D）,respectively.The preparation time and reduction of working length after preparation were measured.Pre-and postoperative images were obtained by a scanner and superimposed using Photoshop.Changes of coronal curve and apical curve curvature ,as well as material removal from the inner and outer canal wall at 10 points beginning 1 mm from the end point of the canal ,were measured using ImageJ.Centering ability was determined ,accordingly.The data were analyzed using the one-way ANOVA and Student-Newman-Keuls.Results The preparation time of group A and group B were （ 42.1 ±2.7 ） and （41.5 ±3.2） s respectively,significantly less than that of group C and group D [（62.7 ±2.8）,（62.8 ± 5.2） s]（P〈0.05）.Reductions of working length after preparation were not significantly different among the four groups（P＆gt;0.05）.Coronal curve curvature changes of group A ,group B and group D were （4.69 ± 0.63）°,（4.15 ±0.89）°and （4.13 ±0.59）°respectively,significantly less than that of group C [（5.26 ± 0.70）°],P〈0.05.Apical curve curvature changes were not significantly different among the four groups （P＆gt;0.05）.At the 2 mm point,the centering ability of group A [（ -0.242 ±0.042） mm],group B [（-0.191 ±0.077） mm],and group D[（-0.272 ±0.046） mm] was better than group C [（ -0.343 ± 0.057 mm] significantly（P〈0.05）.At the 3 mm and 4 mm point,the centering ability of group A and group B was better than group C and group D significantly （ P 〈0.05 ）.Whilst at the 5 mm point , the centering ability of group D was better than group A and group B （ P〈0.05 ）.Conclusions Reciproc and WaveOne could complete preparation fast