Evaluation of cyclic fatigue and bending test for different Nickle-Titanium files

To compare cyclic fatigue resistance and bending for three different nickel-titanium (NiTi) rotary files.

A sample of 90 NiTi instruments size (25.06) was divided into three groups with 30 files in each: Race Evo files (FKG Dentaire, Switzerland); Tia Tornado Blue files (TiaDent Inc., Texas- USA); One Curve files (Micro-Mega, France). Then each group was subdivided into two groups with 15 files in each; a bending test was performed for one group, and a dynamic cyclic fatigue test at body temperature was performed for the other group. Files fractured by cyclic fatigue were randomly picked from all tested groups for Scanning Electron Microscopy (SEM) (Jeol, Tokyo, Japan). In addition, the test included measuring the broken part of the files tested using (Electronic Micrometre Calliper with LCD Screen, Inch and Millimetre Conversion, Adoric- Taiwan). Data were statistically analyzed using a one-way ANOVA with Tukey-HSD post hoc test.

It was found that maximum load [gf] was less (meaning more flexible) in the group of Tia Tornado Blue with a statistically significant difference in comparison with Race Evo and One Curve. The number of cycles to fracture (NCF) in the Race Evo group was significantly higher than the groups of One Curve and Tia Tornado Blue.

Within the limitation of the study, it could be concluded that Race Evo files were more resistant to cyclic fatigue fracture and Tia Tornado Blue files were more flexible compared to the other tested files.