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. 2022 Mar 4;47(2):e16.
doi: 10.5395/rde.2022.47.e16. eCollection 2022 May.

Comparison of the cyclic fatigue resistance of One Curve, F6 Skytaper, Protaper Next, and Hyflex CM endodontic files

Charlotte Gouédard  1   2 , Laurent Pino  3 , Reza Arbab-Chirani  4   5 , Shabnam Arbab-Chirani  3 , Valérie Chevalier  2   3
Affiliations

Comparison of the cyclic fatigue resistance of One Curve, F6 Skytaper, Protaper Next, and Hyflex CM endodontic files

Charlotte Gouédard et al. Restor Dent Endod. .

Abstract

Objectives: This study compared the cyclic fatigue resistance of One Curve (C wire) and F6 Skytaper (conventional austenite nickel-titanium [NiTi]), and 2 instruments with thermo-mechanically treated NiTi: Protaper Next X2 (M wire) and Hyflex CM (CM wire).

Materials and methods: Ten new instruments of each group (size: 0.25 mm, 6% taper in the 3 mm tip region) were tested using a rotary bending machine with a 60° curvature angle and a 5 mm curvature radius, at room temperature. The number of cycles until fracture was recorded. The length of the fractured instruments was measured. The fracture surface of each fragment was examined with a scanning electron microscope (SEM). The data were analyzed using one-way analysis of variance and the post hoc Tukey test. The significance level was set at 0.05.

Results: At 60°, One Curve, F6 Skytaper and Hyflex CM had significantly longer fatigue lives than Protaper Next X2 (p < 0.05). No statistically significant differences were found in the cyclic fatigue lives of One Curve, F6 Skytaper, and Hyflex CM (p > 0.05). SEM images of the fracture surfaces of the different instruments showed typical features of fatigue failure.

Conclusions: Within the conditions of this study, at 60° and with a 5 mm curvature radius, the cyclic fatigue life of One Curve was not significantly different from those of F6 Skytaper and Hyflex CM. The cyclic fatigue lives of these 3 instruments were statistically significantly longer than that of Protaper Next.

Keywords: Cyclic fatigue; Endodontics; Nickel-titanium alloy; Rotary files; Scanning electron microscopy.

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Conflict of interest statement

Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Figures

Figure 1
Figure 1. Photographs of the experimental set-up of the rotary bending fatigue machine.
Figure 2
Figure 2. Fracture surfaces of the 4 different instruments, with 2 magnifications. The red circle indicates a zone of crack initiation, and the arrow shows the direction of crack propagation. (A) ProTaper Next, with a magnification of ×160 and ×500. (B) F6 Skytaper, with a magnification of ×150 and ×400. (C) One Curve, with a magnification of ×170 and ×500. (D) Hyflex CM, with a magnification of ×170 and ×500.
See this image and copyright information in PMC

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