Cyclic fatigue resistanceof Hyflex EDM NiTi rotaryfiles in different distancesof pecking motion

Aim: The purpose of this study was to evaluate the effect of different distances of pecking motion on the cyclic fatigue of Hyflex EDM OneFile (Coltene/Whaledent AG, Altstatten, Switzerland) in simulated curved canal. Methods: Sixty Hyflex EDM OneFile (#25/0.08) files were tested at three different pecking depths: G(1): 1-mm depth, G(2): 2-mm depth, G(3): 3-mm depth, and G(4): 4-mm depth. Cyclic fatigue resistance was tested measuring the time to fracture and the number of cycles to failure (NCF) in an artificial canal with a 60° angle and a 3-mm radius of curvature. Data were analyzed using the analysis of variance test and the Student-Newman-Keuls test for multiple comparisons. Results: There was a significant difference between the four groups for the NCF (p < 0.05). G(1) group had lower NCF compared to the other groups. There was a significant difference between group 4 (1278.9) and the others (p < 0.05). Groups 2 and 3, with NCF means of 714.4 and 872.2, respectively, did not show any significant difference between them (p > 0.05). Conclusion: The results showed that different pecking distances can significantly extend the life span of Hyflex EDM rotary files. Our results suggest that a longer pecking depth may reduce the risk of instrument fracture.