Drukteinis et al. (2020) evaluated the shaping ability, centering accuracy, cyclic fatigue resistance, and fracture characteristics of three heat-treated nickel-titanium (NiTi) rotary file systems: EdgeFile® X5 (EdgeEndo), HyFlex CM, and HyFlex EDM. Using micro-computed tomography (µCT), the authors found that all three systems maintained the original canal anatomy equally well, with comparable canal transportation, dentin removal, and percentages of unprepared canal surfaces, demonstrating similar shaping performance. However, significant differences were observed in cyclic fatigue resistance. EdgeFile X5 exhibited the highest resistance to cyclic fatigue, achieving an average of 4,504 cycles to failure—substantially greater than HyFlex EDM (3,132 cycles) and HyFlex CM (1,143 cycles). These findings indicate that while all three systems provide effective and conservative canal preparation, EdgeFile X5 offers superior durability and resistance to fracture, likely due to its proprietary Fire-Wire™ heat treatment. Fractographic analysis confirmed typical fatigue fracture patterns for all instruments, with EdgeFile displaying the highest fatigue endurance despite showing expected microscopic wear after extended testing. Overall, the study concluded that EdgeFile X5 combines excellent shaping ability with significantly greater cyclic fatigue resistance, making it a highly durable option for endodontic instrumentation, particularly in curved canals.
