Fatigue Resistance of a 3-dimensional Conforming Nickel-Titanium Rotary Instrument in Double Curvatures

• Fatigue resistance of TRUShape in artificial single curvature and in two different artificial double curvature canals is evaluated.
• NiTi files have significantly higher fatigue resistance in a single curvature canal than in the double curvature canals.
• The fatigue resistance of TRUShape is superior to ProFile and Vortex Blue in double curvature canals.

IntroductionFatigue resistance of ProFile, Vortex Blue, and TRUShape files in artificial single curvature and in 2 different artificial double curvature canals was evaluated.MethodsThree files (ProFile, Vortex Blue [size 20/.06], and TRUShape [size 20/.06v]) were subjected to fatigue tests in a single curvature (group 1: 60° curvature) and 2 different double curvatures (group 2: 60° and 30° curvatures; group 3: two 60° curvatures). The time to fracture and the total number of cycles to failure were recorded. The fracture surfaces of the fragments were examined with a scanning electron microscope.ResultsAll files had significantly higher fatigue resistance in a single curvature canal than in the double curvature canals. In a single curvature group, the time to fracture of TRUShape and ProFile was longer than in Vortex Blue files. In both double curvature groups, TRUShape had the longest time to fracture among all files. The fatigue resistance (the time to fracture and number of cycles to failure) of ProFile and Vortex Blue was lower in group 3 than in group 2 (P < .05). However, there was no significant difference in fatigue resistance of TRUShape in the double curvature groups. The length of the fragment of TRUShape was longer than in Vortex Blue and ProFile files in group 3 (P < .05).ConclusionsThe fatigue performance of TRUShape is different in double curvature canals, compared with conventional nickel-titanium rotary files. The fatigue resistance of TRUShape was superior to ProFile and Vortex Blue in double curvature canals.