Static Cyclic Fatigue Resistance of Three Different Thermally Treated Nickel-Titanium Rotary Files: In-vitro Comparative Study

Aim: compare cyclic fatigue resistance, length of the separated fragment and time to file fracture between Race Evo, TruNatomy and ProTaper Next files.Materials and Methods: 75 new NiTi rotary files of ProTaper Next (PTN), TruNatomy (TN) and RaCe EVO (RE) were divided into 3 equal groups (n=25). Tested files were subjected to static cyclic fatigue protocol by rotating the file in 45o curved simulated canal in stainless steel block with 5 mm radius until the file separated. Time to file fracture and length of separated instrument was recorded while the number of cycles to fracture (NCF) were calculated. Data was statistically analyzed using one way ANOVA test.Results: NCF in RE group was significantly higher than that obtained from TN and PTN, while PTN was lowest significantly. RE group recorded the least time to fracture between the tested groups with no significant difference between TN and PTN groups. PTN recorded significantly longer separated fragments than the other two tested groups.Conclusion: Within the limits of the current investigation, RE files demonstrated the highest cyclic fatigue resistance in comparison to TN and PTN NiTi files regarding a static cyclic fatigue testing protocol. However, the RE files also fractured in a shorter duration than the other two systems.