Comparative evaluation of Cyclic Fatigue Resistance of Hyflex CM with newer gold treated NiTi file systems: an in vitro study

Objective: The aim of this study was to evaluate cyclic fatigue resistance of three control memory wire based instruments namely, Hyflex CM NiTi files (Coltene/ Whaldent, Switzerland), M3 Pro Gold NiTi files (United Dental, Shanghai, China) and NeoEndo Flex NiTi files (Orikam health care, Gurgaon, India) in an extreme canal curvature.Method: A total of 30 NiTi instruments of three different rotary systems weretested using a custom made jig that reproduces a curvature of 90° and 5mm radius. All of the files were used in the artificial canals until the fracture occurred. The time to fracture for each group was recorded using digital chronometer. Using the time data, the numbers of cycles to failure (NCF) were calculated. The mean, standard deviation and standard error of the three groups were calculated and statistically analyzed using SPSS software 21.0 version. One-way analysis of variance (ANOVA) was done to determine significant differences among the systems, between groups and within groups. Post Hoc test of Tukey was performed to identify pair-wise significance. Results: NeoEndo Flex had highest NCF followed by M3 Pro Gold and Hyflex CM with a mean of 425.310, 380.060 and 259.960 NCF respectively. On one way ANOVA the three groups had statistically significant difference (P value = 0.025) and on Post hoc Tukey HSD between all the three groups NeoEndo Flex vs. Hyflex CM was statistically significant (P value = 0.024).Conclusion: Within the limitations of present study, NeoEndo Flex had significantly higher cyclic fatigue resistance than Hyflex CM in 90 degree canal curvature and among all the three NiTi systems.