热处理连续旋转镍钛锉对重度弯曲根管成形能力的比较研究

Comparative study on the shaping ability of thermally treated continuous rotating nickel-titanium systems for severely curved simulated canals

目的比较3种不同热处理连续旋转机用镍钛锉与传统镍钛锉预备重度弯曲根管的成形能力,为其临床应用提供实验依据。方法将60个重度弯曲(45°)树脂模拟根管随机分为4组,每组15个,分别使用Twisted File锉(R-相技术,TF组)、ProTaper Next锉(M-wire技术,PTN组)、Hyflex CM锉(CM-wire技术,HCM组)以及Mtwo锉(传统技术,Mtwo组)进行根管预备,并记录预备时间,测量4个实验组预备前后根管工作长度的变化,采用失重法比较树脂切削量,数码相机采集预备前后根管的形态,使用Photoshop软件将其重叠,通过ImageJ软件测量根管树脂去除量,计算中心定位能力。使用单因素方差分析、Kruskal-Wallis检验及Bonferroni检验进行统计学分析。结果4种器械预备前后根管工作长度变化的差异无统计学意义(P>0.05)。Mtwo组预备后树脂切削量最多(P<0.05),其余3组之间树脂切削量的差异无统计学意义(P>0.05)。在距根尖孔0 mm及7~9 mm的观测位点,4组器械的中心定位能力无明显差异(P>0.05);在距根尖孔1~2 mm的观测位点(即根方弯曲部分),TF组的中心定位能力较其他3组更好,Mtwo组的偏移量在根方弯曲部分及弯曲最凸点冠方均为最大(P<0.05)。TF组的根管预备时间最短,PTN组次之,与其他2组的差异有统计学意义(P<0.05)。结论4组器械均可快速有效地预备弯曲根管,且可较好地保持重度弯曲根管的原始形态;与传统镍钛锉相比,3种热处理镍钛锉均具有更好的中心定位能力,其中Twisted File锉在根尖区的中心定位能力最好。

Objective This study aimed to compare the centring ability of three different thermally treated continuous rotating systems in severely curved simulated canals.Methods Sixty single-curved canals in resin blocks were prepared by using the Twisted File(group TF,R-phase),ProTaper Next(group PTN,M-wire),Hyflex CM(group HCM,CM-wire),and Mtwo(group Mtwo,traditional nickel-titanium alloy)systems(n=15),and the preparation time was recorded.The reduction in the working length after the preparation was measured.The weight change in the resin block was measured using an electronic balance.Images of pre-and post-instrumentation were recorded by digital camera and then superimposed by Photoshop.The amount of resin removed was measured by ImageJ.The differences between the groups were determined using one-way ANOVA,the Kruskal-Wallis and post hoc Bonferroni tests.Results No significant difference was observed in the changes in working length in the four groups(P>0.05).The weight change in the resin block was highest in the group Mtwo(P<0.05),and those of the three other groups were not significantly different(P>0.05).No significant difference was observed in the transportation of the canal at the apical foramen and in the coronal plane portion among four nickel-titanium instruments(P>0.05).In the apical part of the curvature,the group TF had the least root canal transportation(P<0.05),and the group Mtwo had higher root canal transportation than the three other groups in each measurement point(P<0.05).The Twisted File and the ProTaper Next could complete the preparation in a shorter time than the Mtwo and the Hyflex CM(P<0.05).Conclusion All tested files could prepare and maintain the original shape of severely curved canals effectively.This study showed that the Twisted file,ProTaper Next,and Hyflex CM systems had better centring ability than the Mtwo system and that the Twisted file system was demonstrated to have superior shaping ability compared with the others in the apical part.