Department of Conservative Dentistry, School of Dentistry, Dental and Life Science Institute, Dental Research Institute, Pusan National University, Yangsan, Korea.
Department of Conservative Dentistry, School of Dentistry, The University of Jordan, Amman, Jordan.
J Endod. 2021 Jan;47(1):88-93. doi: 10.1016/j.joen.2020.09.011. Epub 2020 Sep 19.
This study aimed to compare the torsional resistances and fracture modes of WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland) and Reciproc Blue (VDW, Munich, Germany) using the repetitive torsional loading (RTL) method and the conventional single-rotation (STL) method.
A 3-mm file tip was fixed with a brass plate, and a torsional load was applied using a custom device. In the RTL method, the file was driven counterclockwise at 50 rpm until it achieved the preset torque of 0.5 Ncm; thereafter, it was returned to its original position. This recovery of the file to its original position was defined as 1 torsional loading cycle; the number of repetitive load cycles until fracture was counted. In the STL method, the files were rotated at a constant rate of 2 rpm in a counterclockwise direction until file fracture. The fragments fractured by the 2 methods were compared under a scanning electron microscope to examine the topographic features of the fractured surfaces and longitudinal aspects.
With the RTL method, Reciproc Blue showed a higher number of repetitive load cycles until fracture than WaveOne Gold (P < .05). With the STL method, Reciproc Blue also had a higher ultimate strength than WaveOne Gold (P < .05). Scanning electron microscopic findings of the fractured specimens from the 2 test methods showed different features of torsional failure.
Within the study limitations, both the RTL and STL methods conferred similar torsional resistance. Therefore, the clinically relevant RTL method with repetitive and reciprocation motion can be used for testing torsional resistance.
本研究旨在使用重复扭转加载（RTL）方法和传统的单转（STL）方法比较 WaveOne Gold（登士柏西诺德，Ballaigues，瑞士）和 Reciproc Blue（VDW，慕尼黑，德国）的扭转阻力和断裂模式。
将 3 毫米的锉尖端固定在黄铜板上，并使用定制设备施加扭转载荷。在 RTL 方法中，锉逆时针以 50 rpm 的速度驱动，直到达到预设的 0.5 Ncm 扭矩；然后，它返回其原始位置。锉回到原始位置被定义为 1 个扭转加载循环；记录直到断裂的重复加载循环数。在 STL 方法中，锉以逆时针方向以恒定的 2 rpm 速率旋转，直到锉断裂。用 2 种方法断裂的碎片在扫描电子显微镜下进行比较，以检查断裂表面和纵向方面的形貌特征。
用 RTL 方法，Reciproc Blue 显示出比 WaveOne Gold 更高的重复加载循环次数直到断裂（P <.05）。用 STL 方法，Reciproc Blue 的极限强度也高于 WaveOne Gold（P <.05）。2 种测试方法的断裂标本的扫描电子显微镜检查结果显示出扭转失效的不同特征。
在研究限制范围内，RTL 和 STL 方法都提供了相似的扭转阻力。因此，可以使用具有重复和往复运动的临床相关 RTL 方法来测试扭转阻力。
