Aim: The purpose of this study was to compare the resistance to cyclic fatigue of three nickel-titanium (NiTi) endodontic instruments from Protaper Gold (PTG), OneShape (OS), and Twisted files (TF).
Methodology: A total of 45 nickel-titanium instruments were tested and divided into 3 experimental groups (n = 15): group 1, Protaper Gold (F2 25/.08); group 2, OneShape (25/.06) file; and group 3, Twisted file (25/.06). The testing device was specially designed for this experiment. The time and cycles to failure were calculated. The data were compared for differences by using 2-way analysis of variance (p < 0.05).
Results: Statistical analysis revealed that PTG showed the statistically significantly highest mean cyclic fatigue value, while TF showed statistically significantly lower mean cyclic fatigue value. OS system showed the statistically significantly lowest mean cyclic fatigue value.
Conclusions: ProTaper Gold files demonstrated significantly higher cyclic fatigue resistance than OneShape and Twisted files, while OneShape files revealed the lowest cyclic fatigue resistance. The enhanced alloy properties of ProTaper Gold may be the main reason for this difference.