A Comparative Study of Cyclic Fatigue Resistance of Different Types of Endodontic Instruments: An in Vitro Study

Background and Objectives: Nickel-titanium (NiTi) rotary files are routinely utilized in root canal instrumentations for their flexibility and competency. However, they are susceptible to fracture due to cyclic fatigue, particularly in curved canals. The objective of the current study is to investigate and compare the cyclic fatigue resistance of different nickel-titanium (NiTi) rotary instruments. The tested instruments were Protaper Gold (PTG), HyFlex EDM (HEDM), 2Shape (TS1) and TruNatomy (TN). Materials and Methods: A total of forty NiTi endodontic rotary instruments were split into four study groups (n = 10 each). Group 1: Protaper Gold (F2 25/.08), group 2: HyFlex EDM (25/.08), group 3: 2Shape (25/.04) and group 4: TruNatomy (26/.04). A custom-made stainless-steel block having simulated canal with 60° angle of curvature and 5 mm radius of curvature was used to test the cyclic fatigue resistance. The number of cycles required for fracture with the length of the fractured segment were calculated and the data were statistically analyzed utilizing one-way analysis of variance (p < 0.05). Results: The results demonstrated that HyFlex EDM had the highest statistically significant mean cyclic fatigue value, followed by 2Shape, Protaper Gold and TruNatomy respectivly. Conclusion: The alloy properties and manufacturing processes of the evaluated rotary nickel–titanium systems had a direct influence on their capability to resist cyclic fatigue. HyFlex EDM files demonstrated greater fatigue resistance compared to 2 Shape, Protaper Gold and TruNatomy. Keywords: Cyclic Fatigue, NiTi rotary intstruments, Protaper Gold, HyFlex EDM, 2Shape, Trunatomy