Dynamic cyclic and torsional fatigue resistance of TruNatomy compared with different nickel-titanium rotary instruments.

This study evaluated the dynamic cyclic and torsional fatigue resistance of recently introduced TruNatomy instruments (TRN) and compare with HyFlex CM (HFC), Vortex Blue (VB) and FlexMaster (FM) instruments. Size 20, 0.04 taper of TRN, HFC, VB and FM instruments was tested for dynamic cyclic and torsional fatigue resistance. Dynamic cyclic fatigue resistance was evaluated using an artificial canal with a radius of 5 mm and a 90° angle of curvature. The number of cycles to failure (NCF) was calculated. The dynamic torsional fatigue resistance was evaluated by holding a 5 mm of the tip of each instrument in a metal block with composite resin. Torsional fatigue resistance was recorded by counting the number of load applications before fracture for each instrument. The HFC instruments had greater fatigue resistance than VB, TRN and FM. FM had a higher resistance to torsional stress than TRN, HFC and VB instruments.