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

Abstract

Introduction: The purpose of this study was to evaluate the effect of 2 different temperatures (20 C and 37 C) on the cyclic fatigue life of rotary instruments and correlate the results with martensitic transformation temperatures. Methods: Contemporary nickel-titanium rotary instruments (n = 20 each and tip size #25, including Hyflex

The Effect of Temperature on Cyclic Fatigue of Nickel-titanium Rotary Endodontic Instruments

“…This is in agreement with previous studies (6,7) in which increasing the temperature was found to decrease the NCF. In one study, NiTi rotary Basic Research-Technology instruments were made from wire to a tip size of 30 with a .06 taper (6).…”

Comparison of cyclic fatigue resistance and bending properties of two reciprocating nickel‐titanium glide path files

“…It has been demonstrated that the cyclic fatigue resistance of thermomechanically treated NiTi file is affected by ambient temperature (de Vasconcelos et al . , Dosanjh et al . , Grande et al .…”

“…All files were operated in 35°C water (de Vasconcelos et al . ) using a torque‐controlled endodontic motor (VDW Gold; VDW) following the instructions given by the manufacturers: R‐Pilot in the ‘Reciproc ALL’ program and WOG Glider in the ‘WaveOne ALL’ program.…”

“…Recent studies reported that ambient temperature might drastically affect the cyclic fatigue resistance of NiTi files (de Vasconcelos et al . , Grande et al . , Plotino et al .…”

Evolution of Nickel–titanium Alloys in Endodontics

“…The tendency for heat-treated alloys to switch back from martensitic to austenitic under stress or when exposed to body temperature was also described in a recent paper in which the authors concluded that a significant proportion of heat-treated alloys (and thus supposed to be working in a martensitic phase) revert to austenitic as soon as they are exposed to body temperature. 45 On the contrary, the metallurgical characteristics of unused and clinically used heat-treated instruments did not seem to be affected by one single clinical use as no variation in the austenite-martensite phase transformation was detected in these instruments.…”