Background/Aim: The present study examined the resistance to cyclic fatigue of three different rotary Ni-Ti instruments: K3XF (Kerr, Orange, CA), HyFlex CM (Coltene/Whaledent, Altstätten, Switzerland) and X7 EdgeFile (EdgeEndo, Albuquerque, New Mexico).
Material and Methods: Thirty instruments (n=30) of each type were used with tip size 25 and 0.04 taper. All instruments were constrained to 600 of curvature with a radius of 5 mm by the use of two grooved stainless steel rods and rotated at a speed of 300 rpm and 3.0 Ncm of torque. The time until separation was recorded for each of the instruments and the number of cycles to fracture (NCF) was calculated. Statistical analysis was performed using R Programming language.
Results: The X7 EdgeFile instrument showed significantly greater resistance to cyclic fatigue when compared to the HyFlex CM and the K3XF with mean NCF for each instrument 1046 ± 311, 707 ± 219 and 360 ± 96 respectively. HyFlex CM performed significantly better than K3XF.
Conclusions: The X7 EdgeFile Ni-Ti file appears to be significantly more resistant to fracture, due to flexural fatigue, than the HyFlex CM and the K3XF.