Fatigue and nanomechanical properties of K3XF nickel‐titanium instruments

Abstract

The fatigue life of K3XF instruments under water is longer than it is for K3XF instruments in air. There was no work-hardening effect on K3XF instruments subjected to the fatigue process.

Evidence for Reduced Fatigue Resistance of Contemporary Rotary Instruments Exposed to Body Temperature

“…Importantly, it has been shown that in vivo intracanal temperature ranges from 31 C-35 C (17, 18); moreover, in vitro data suggest that irrigation solutions intracanal will be at body temperature within 30 to 60 seconds after deposition (20). These findings are in line with our pilot data using an infrared thermometer indicating that rotary instruments just after removal from a root canal had surface temperatures of 30.8 C-32.5 C. In agreement with previous findings (16,21) the present data indicate that fatigue life in air is shorter than in water at room temperature, perhaps because of locally elevated temperatures (15,16). To the best of our knowledge, the present study is the first to simulate cyclic fatigue test resistance for endodontic instruments under temperature conditions similar to those of the body.…”

Effect of a Combination of Torsional and Cyclic Fatigue Preloading on the Fracture Behavior of K3 and K3XF Instruments

“…In the present study, the torque and angle of rotation at fracture of K3XF were similar to K3 instruments. Similar findings were reported in previous studies (18,19).…”

“…The manufacturer claims that K3XF (SybronEndo, Orange, CA) provides clinicians with the basic features of the original K3 (SybronEndo) plus an extraordinary new level of flexibility and resistance to cyclic fatigue with the proprietary R-Phase technology. Recent studies (16)(17)(18)(19) have shown that K3XF instruments have fatigue resistance superior to K3 NiTi instruments. On the other hand, K3XF instruments maintain the same torsional properties as conventional superelastic NiTi instruments (K3) (18,20).…”

'In Vitro' Comparison of K3XF and TFA Cyclic Fatigue Resistance in Continuous Rotation and Adaptive Motion

“…Since we wanted to eliminate factors other than cyclical fatigue that could alter the mechanisms of separation of the instruments [4] . All the instruments that presented defects or microcracks were excluded from the study.…”

“…However, in the K3XF groups, there was no significant difference between torque value and distortion angle among groups with and without preload. The length of the fragments varied between 2.7-3.0 mm [4] . Besides, the NiTi instruments are processed by a thermal treatment after finishing their fabrication with the objective of improving their flexibility, strength, and modify the crystalline structure of the alloy to accommodate some of the internal stress caused by the manufacturing process.…”