Sharroufna and Mashyakhy evaluated the effect of 10 cycles of autoclave sterilization on the cyclic fatigue resistance of three heat-treated nickel-titanium (NiTi) rotary file systems: EdgeFile® X7 (EdgeEndo), Vortex Blue, and TRUShape. The instruments were tested in a simulated curved canal, and the number of cycles to failure (NCF) was measured. EdgeFile X7 demonstrated the highest cyclic fatigue resistance in both sterilized and nonsterilized conditions, outperforming Vortex Blue and TRUShape. Notably, repeated autoclave sterilization produced a statistically significant increase in the fatigue resistance of EdgeFile X7, with NCF increasing from 756 to 1,199 cycles after sterilization. In contrast, Vortex Blue and TRUShape showed only small, non-significant improvements following sterilization. The authors attributed EdgeFile X7’s superior performance to its proprietary FireWire™ heat-treated alloy, which appears to enhance flexibility and fatigue resistance while benefiting from repeated heat sterilization. The study concluded that autoclave sterilization does not compromise—and may actually improve—the cyclic fatigue resistance of modern heat-treated NiTi instruments, with EdgeFile X7 exhibiting the greatest durability and statistically superior performance among the systems evaluated.
