Summary:
Purpose: to investigate cyclic flexural fatigue resistance of GT series X rotary files made from the newly developed M-wire nickel-titanium alloy compared with GT and Profile nickel-titanium files made from a conventional nickel-titanium alloy.
N= 15 files of each type , size 30/04.
Materials/Methods:
-A simple device was specifically constructed to measure the time each file type required to fail under cyclic flexural fatigue testing (Figure 1).
-Each file was operated at a constant degree 300 rpm by using 16:1 reduction handpiece powered by torque-controlled electric motor until instrument fracture was visually observed.
Most highlighted Results:
- The results of this experiment indicated that the GT series X files had superior cyclic flexural fatigue resistance than the other 2 file types made from a conventional nickel-titanium alloy (P = .004).
- The difference between the Profile and the GT files was not statistically significant.
Clinical significance:
The findings of this study suggest that size 30/0.04 nickel-titanium rotary files made from the newly developed M-wire alloy have better cyclic flexural fatigue resistance than files of similar design and size made from the conventional Ni-Ti alloy.

