Vadhana Sekar, SaravanaKarthikeyan Balasubramanian, Nandini Suresh, Velmurugan Natanasabapathy
Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College and Hospital, Meenakshi Academy of Higher Education and Research, Maduravoyal, Chennai, India.
Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College and Hospital, Meenakshi Academy of Higher Education and Research, Maduravoyal, Chennai, India.
J Endod. 2014 Jul;40(7):995-9. doi: 10.1016/j.joen.2013.12.010. Epub 2014 Mar 6.
The purpose of this study was to evaluate and compare the cyclic fatigue resistance of RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and Mtwo (VDW, Munich, Germany) rotary files in continuous rotation and reciprocating motion.
A total of 60 new rotary Mtwo and RaCe files (ISO size = 25, taper = 0.06, length = 25 mm) were selected and randomly divided into 4 groups (n = 15 each): Mtc (Mtwo NiTi files in continuous rotation), Rc (RaCe NiTi files in continuous rotation), Mtr (Mtwo NiTi files in reciprocating motion), and Rr (RaCe NiTi files in reciprocating motion). A cyclic fatigue testing device was fabricated with a 60° angle of curvature and a 5-mm radius. All instruments were rotated or reciprocated until fracture occurred. The time taken for each instrument to fracture and the length of the broken fragments were recorded. All the fractured files were analyzed under a scanning electron microscope to detect the mode of fracture. The Kolmogorov-Smirnov test was used to assess the normality of samples distribution, and statistical analysis was performed using the independent sample t test.
The time taken for the instruments of the Mtr and Rr groups to fail under cyclic loading was significantly longer compared with the Mtc and Rc groups (P < .001). Scanning electron microscopic observations showed that the instruments of all groups had undergone a ductile mode of fracture. The length of the fractured segments was between 5 and 6 mm, which was not statistically significant among the experimental groups.
Mtwo and RaCe rotary instruments showed a significantly higher cyclic fatigue resistance in reciprocating motion compared with continuous rotation motion.
本研究的目的是评估和比较RaCe（FKG Dentaire，瑞士拉绍德封）和Mtwo（VDW，德国慕尼黑）旋转锉在连续旋转和往复运动中的抗循环疲劳性能。
共选取60支新的Mtwo和RaCe旋转锉（ISO尺寸 = 25，锥度 = 0.06，长度 = 25 mm），随机分为4组（每组n = 15）：Mtc（Mtwo镍钛锉连续旋转）、Rc（RaCe镍钛锉连续旋转）、Mtr（Mtwo镍钛锉往复运动）和Rr（RaCe镍钛锉往复运动）。制作了一个曲率为60°、半径为5 mm的循环疲劳测试装置。所有器械旋转或往复运动直至断裂。记录每支器械断裂所需的时间和断裂碎片的长度。所有断裂的锉在扫描电子显微镜下进行分析以检测断裂模式。采用柯尔莫哥洛夫-斯米尔诺夫检验评估样本分布的正态性，并使用独立样本t检验进行统计分析。
与Mtc和Rc组相比，Mtr和Rr组器械在循环加载下失效所需的时间显著更长（P <.001）。扫描电子显微镜观察显示，所有组的器械均发生了韧性断裂模式。断裂段的长度在5至6 mm之间，各实验组之间无统计学差异。
与连续旋转运动相比，Mtwo和RaCe旋转器械在往复运动中表现出显著更高的抗循环疲劳性能。
