Cyclic Fatigue Resistance of Hyflex EDM and ProTaper Gold Files at Different Locations of Canal Curvature

Aim: Study's purpose was to evaluate and compare the fatigue resistance of ProTaper Gold and Hyflex EDM files at five different locations of canal curvature. Methods: Two types of NiTi files; ProTaper Gold and Hyflex EDM (n=80) with similar sizes (25/0.08) were used as two main groups (n=40), each group subdivided into five subgroups (n=8) according to distance from the orifice to curvature which are; 11, 10, 8, 6 and 5 mm. Five stainless steel canals were fabricated. Each canal had 16 mm length, 1.5 mm width and single curvature with 3-mm radius and 60° angle. Fractured samples were examined under a scanning electron microscope. Independent t-test, One-way ANOVA and Posthoc tests assessed the data statistically. Results: Number of cycles to fatigue for the Hyflex EDM file was significantly higher than the ProTaper Gold file at all curvature levels (p≤0.05). The files demonstrated significantly higher number of cycles to fatigue in canals of (10 and 11) mm when compared to the canals of (5, 6, and 8) mm (p≤0.05). Conclusion: Hyflex EDM files showed higher fatigue resistance than ProTaper Gold files. The canal curvature position had a substantial impact on the resistance of the NiTi file, with short life coronally.