Evaluation of cyclic flexural fatigue of M-wire nickel-titanium rotary instruments. 

By Al-Hadlaq SM, Aljarbou FA, AlThumairy R.

Date: 01/2010
Journal: JOE

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.