Department of Conservative Dentistry and Endodontics, Guanghua School of Stomatology, Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University Guangzhou, China; Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, Vancouver, Canada.
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, Vancouver, Canada; Department of Materials Engineering, The University of British Columbia, Vancouver, Canada.
J Endod. 2017 Nov;43(11):1847-1851. doi: 10.1016/j.joen.2017.06.033. Epub 2017 Sep 23.
The purpose of this study was to introduce a new fatigue test model that simulates the clinical situation for evaluating the corrosion effect of 5.25% sodium hypochlorite (NaOCl) on nickel-titanium (NiTi) files and to evaluate the effect of 3 different temperatures (22°C, 37°C, and 60°C) on the cyclic fatigue of these files.
Three NiTi files (size 25/.04), K3 (SybronEndo, Orange, CA), K3XF (SybronEndo), and Vortex (Dentsply Tulsa Dental Specialties, Tulsa, OK), were subjected to cyclic fatigue tests inside a novel artificial ceramic canal with a curvature of 60° and a 5-mm radius. A 19-mm-long file segment from the tip was introduced into the canal and immersed in water or 5.25% NaOCl at 3 different temperatures, and the number of revolutions to fracture (N) was recorded. The fracture surface of all fragments was examined by a scanning electron microscope. Data were analyzed using univariate analysis of variance with the significance level at 0.05.
The N of Vortex files was the highest followed by K3XF and K3 (P < .05) at all conditions. The N of all files was highest at 22°C and lowest at 60°C (P < .05). However, no difference in N was detected in Vortex files between 22°C and 37°C. The N of all files in 5.25% NaOCl was shorter than that in water although there was no statistically significant difference. No pitting or crevice corrosion was observed on the fracture surface.
NaOCl, 5.25%, does not significantly affect the fatigue behavior of NiTi files. The fatigue resistance should be tested under specific temperature conditions. The austenite finish temperature of a file is important in determining the fracture risk at body temperature.
本研究旨在介绍一种新的疲劳测试模型，该模型模拟临床情况，评估 5.25%次氯酸钠（NaOCl）对镍钛（NiTi）锉的腐蚀效果，并评估 3 种不同温度（22°C、37°C 和 60°C）对这些锉的循环疲劳的影响。
将 3 种 NiTi 锉（规格 25/.04），K3（SybronEndo，Orange，CA）、K3XF（SybronEndo）和 Vortex（Dentsply Tulsa Dental Specialties，Tulsa，OK）置于新型人工陶瓷管内进行循环疲劳测试，管的曲率为 60°，半径为 5mm。将 19mm 长的锉尖端段插入管内，并浸入水或 5.25% NaOCl 中，记录断裂时的转数（N）。用扫描电子显微镜检查所有碎片的断裂面。使用单变量方差分析进行数据分析，显著性水平为 0.05。
在所有条件下，Vortex 锉的 N 最高，其次是 K3XF 和 K3（P<.05）。在所有温度下，所有锉的 N 在 22°C 时最高，在 60°C 时最低（P<.05）。然而，在 22°C 和 37°C 之间，Vortex 锉的 N 没有差异。所有锉在 5.25% NaOCl 中的 N 均短于水中，尽管无统计学差异。在断裂面上未观察到点蚀或缝隙腐蚀。
5.25% NaOCl 对 NiTi 锉的疲劳性能没有显著影响。应在特定温度条件下测试疲劳强度。锉的奥氏体终了温度对体温下的断裂风险很重要。
