Department of Conservative and Preventive Dentistry, Division of Endodontology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
Int Endod J. 2020 Aug;53(8):1153-1161. doi: 10.1111/iej.13319. Epub 2020 May 29.
To study the impact of dentine cutting efficiency of rotary instruments on the lateral force they create when instrumenting simulated root canals in bovine dentine.
Lateral cutting efficiency of austenitic files (ProTaper Universal) was compared to that of counterparts of a reported identical geometrical design with a martensite phase component (ProTaper Gold) in bovine dentine disks (n = 6). Instrument shapes were studied using digital microscopy. The intracanal lateral force exerted by the two systems in simulated premolars (n = 9) made from bovine incisor roots containing a standardized narrow root canal of 16 mm length was monitored using a testing apparatus equipped with a torque-controlled endodontic motor/handpiece. Data were compared using parametric statistics, alpha error = 0.05.
The geometrical design of the two systems under investigation was found to be identical. The martensitic nickel-titanium rotary files had a significantly (t-test, P < 0.05) higher lateral cutting efficiency than austenitic counterparts. This difference, however, did not impact the lateral force that was created when instrumenting simulated premolar root canals. Furthermore, lateral force peaks were generated with the progressively tapered instruments under investigation towards the full working length. Even though a glide path was prepared, the first instrument in the full-length sequence (S1) created the highest lateral force (anova/Tukey's HSD, P < 0.05).
The current experimental set-up allows the study of the lateral force generated during root canal instrumentation. This force was not influenced by the dentine cutting efficiency of the instruments under investigation, but rather by their geometrical design.
研究旋转器械在牛牙本质中切割牙本质的效率对其在根管预备过程中产生侧向力的影响。
比较了奥氏体锉（ProTaper Universal）和具有马氏体相成分的同几何设计锉（ProTaper Gold）在牛牙本质圆盘（n=6）中的侧向切削效率。使用数字显微镜研究器械的形状。使用配备扭矩控制根管马达/手机的测试设备，监测来自牛切牙根的模拟前磨牙（n=9）内根管的两个系统产生的根管内侧向力，这些切牙根含有标准化的 16mm 长的狭窄根管。使用参数统计方法比较数据，alpha 误差=0.05。
发现研究的两个系统的几何设计完全相同。马氏体镍钛旋转锉的侧向切削效率明显（t 检验，P<0.05）高于奥氏体锉。然而，这种差异并没有影响到在预备模拟前磨牙根管时产生的侧向力。此外，在研究的逐渐变细的器械上产生了侧向力峰值，直至完全工作长度。即使制备了导丝通路，全长序列中的第一个器械（S1）产生的侧向力最高（anova/Tukey 的 HSD，P<0.05）。
目前的实验设置允许研究根管预备过程中产生的侧向力。该力不受研究器械牙本质切削效率的影响，而是受其几何设计的影响。
