Bharath Naga Reddy, Department of Conservative Dentistry and Endodontics, Adhiparasakthi Dental College and Hospital, Melmaruvathur, Tamil Nadu, India, Phone: +91 9444792260, e-mail:
Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan, Saudi Arabia.
J Contemp Dent Pract. 2021 Nov 1;22(11):1243-1249.
To compare and analyze the cyclic fatigue resistance of novel TruNatomy files against the conventionally used rotary files and reciprocating files in a simulated canal system with curvatures in the middle, apical portions root, and S-shaped canal employing scanning electron microscopy.
Endodontic files tested in the study include ProTaper, HyFlex EDM, Reciproc blue, and TruNatomy files operated in a simulated root canal system. A total of 96 files were employed in this study. They were categorized into four groups. Group 1 employed 24 TruNatomy files, group 2 employed 24 ProTaper gold files, group 3 employed 24 HyFlex EDM files, and group 4 employed 24 Reciproc blue files. All the groups employed eight files each under three subgroups namely A, B, and C representing middle, apical, and double curvatures, respectively. Artificial grooves were incorporated in the stainless steel blocks having three different curvatures. All the file systems were operated with a torque-controlled electric motor. The files were engaged in the artificial canal until the occurrence of fracture. The time required for the fracture was noted. Length of fractured tip was measured using the digital Vernier caliper. The number of cycles of failure (NCF) was calculated. The fractured parts were subjected to scanning electron microscope to analyze the mode of fracture.
TruNatomy files had the highest mean NCF values of 588.01 in middle curvature, 1,321 in apical curvature, and 642.5 in S-shaped curvature HyFlex EDM and Reciproc blue file system exhibited comparable cyclic fatigue resistance among them. ProTaper gold file system exhibited least mean NCF values of 158.13 in the middle, 196.5 in the apical curvature, and 116.88 in the S-shaped canal system. Middle portion fractured first than the apical curvature. The mean length of fractured segments was found to be insignificant among the experimental study groups tested.
All the file systems employed in the study had good cyclic fatigue resistance while TruNatomy files had the highest cyclic fatigue resistance while HyFlex EDM and Reciproc blue had comparable fatigue resistance. ProTaper gold file system had the least fatigue resistance at different radius of curvature in the simulated canal system in the apical and middle portions and S-shaped root canal.
The selection of file systems in cleaning and shaping protocols is an enigma to the endodontics. This study explored the selection protocols for the execution of root canal preparation. Heat treatment of nickel-titanium (NiTi) endodontic files had improved the cyclic fatigue résistance significantly enhancing the clinical life of file systems.
通过扫描电子显微镜比较和分析在具有中部、根尖和 S 形根管弯曲的模拟根管系统中，新型 TruNatomy 文件与传统使用的旋转文件和往复文件的循环疲劳阻力。
研究中测试的根管锉包括 ProTaper、HyFlex EDM、Reciproc blue 和 TruNatomy 文件，在模拟根管系统中操作。本研究共使用了 96 根锉。它们被分为四组。第 1 组使用 24 根 TruNatomy 文件，第 2 组使用 24 根 ProTaper Gold 文件，第 3 组使用 24 根 HyFlex EDM 文件，第 4 组使用 24 根 Reciproc blue 文件。每组都有 8 根锉，分别在三个亚组 A、B 和 C 下，分别代表中部、根尖和双弯曲。在具有三种不同曲率的不锈钢块中加入人工凹槽。所有文件系统都在扭矩控制的电动机上运行。锉刀在人工管道中一直工作，直到发生断裂。记录断裂所需的时间。使用数字游标卡尺测量断裂尖端的长度。计算失效的循环次数（NCF）。对断裂部分进行扫描电子显微镜分析，以分析断裂模式。
TruNatomy 文件在中部曲率、1321 在根尖曲率和 642.5 在 S 形曲率下具有最高的平均 NCF 值，HyFlex EDM 和 Reciproc blue 文件系统之间具有相当的循环疲劳阻力。ProTaper Gold 文件系统在中部曲率、196.5 在根尖曲率和 116.88 在 S 形根管系统中表现出最低的平均 NCF 值。中部首先断裂，然后是根尖曲率。测试的实验组之间，断裂段的平均长度没有明显差异。
研究中使用的所有文件系统都具有良好的循环疲劳阻力，而 TruNatomy 文件具有最高的循环疲劳阻力，而 HyFlex EDM 和 Reciproc blue 具有相当的疲劳阻力。ProTaper Gold 文件系统在模拟根管系统的不同半径曲率下，在根尖和中部以及 S 形根管中具有最低的疲劳阻力。
在清洁和成型方案中选择文件系统对牙髓学来说是一个谜。本研究探讨了执行根管准备的选择方案。镍钛（NiTi）根管锉的热处理显著提高了循环疲劳阻力，显著提高了文件系统的临床寿命。
