Differences in cyclic fatigue lifespan between two different heat treated NiTi endodontic rotary instruments: WaveOne Gold vs EdgeOne Fire

Abstract

Background: Aim of this study is to investigate the cyclic fatigue resistance of the Gold treated WaveOne Gold and the Firewire treated EdgeOne Fire instruments. The null hypotesis was that there were no differences between the lifespan of Gold treated and FireWire treated instruments when subjected to cyclic fatigue tests. Material and Methods: 40 new NiTi instruments with a length of 25 mm were tested: 20 Wave One Gold Medium (WOG), tip size 35 and variable taper (Dentsply Maillefer, Ballaigues, Switzerland) and 20 Edge One Fire (EOF) (EdgeEndo, Albuquerque, New Mexico) tip size 35 and the same variable taper. A mobile support for the electric handpiece and a stainless-steel block containing the artificial canals were used. The same artificial root canal with a 90 degrees angle of curvature and 2 mm radius of curvature was used for all the tested instruments and the WOG counter-clock wise reciprocating motion with an engaging angle of 150° and a disengaging angle of 30° at 300 rpm, was selected for the test. All instruments were inserted at the same length (18mm) and then rotated in the same reciprocating motion until fracture occurred: the time was stopped as soon as the fracture was visible and video-recorded with a 1/100 sec chronometer. Differences among groups were statistically evaluated with an analysis of variance test ANOVA (significance level was set at p<0.05). Results: Mean values of time to fracture (TtF) for EOF instruments were 28,00 seconds (SD +/-2,64) and for WOG instruments were 14,67 seconds (SD +/-2,41). Statistical analysis found significant differences between the TtF of the two instruments (p<0,05). Conclusions: Firewire instruments resulted to be about two times more resistant to cyclic fatigue when compared with identical instruments made with Gold treatment.

Influence of the Pecking Motion Frequency on the Cyclic Fatigue Resistance of Endodontic Rotary Files

“…Different causes of fractures of endodontic instruments have been proposed by many authors and include operator experience [18,19], rotational speed [20,21], the number of uses [22], the number of rotations [23], pre-flaring [24], glide path [25], the angle and radius of the curvature [20,26], and the sterilization of instruments [27]. However, the influence of the frequency of pecking motion performed by the operator on the cyclic fatigue resistance of endodontic rotary instruments has not yet been analyzed.…”

“…Nevertheless, only 12% of published cyclic fatigue studies have used a dynamic fatigue device [30]. Most studies that have compared static and dynamic cyclic fatigue studies have concluded that the time to fracture of endodontic rotary instruments submitted to dynamic cyclic fatigue studies was approximately 20-40% higher than that found in static cyclic fatigue studies [26,[31][32][33][34][35]. Previous dynamic cyclic fatigue devices have been unable to accurately identify the causes of endodontic rotary instrument failures because of the absence of standardization of the axial direction of the pecking motion.…”

Influence of Different Heat Treatments on Torsional and Cyclic Fatigue Resistance of Nickel–Titanium Rotary Files: A Comparative Study

“…Several proprietary heat treatment applications have been developed. Studies have shown that thermal treatments (for files with the same geometry and design) enhance the cyclic fatigue lifespan while, at the same time, reducing the torsional resistance of a file [8][9][10]. Some studies have also compared heat-treated files and non-heat-treated files with different cross-sectional designs in cyclic fatigue tests, which demonstrate that heat treatment may not be the most influential parameter for flexural resistance [11].…”

A new method for assessment of nickel-titanium endodontic instrument surface roughness using field emission scanning electronic microscope

“…Both of systems were reciprocating single-file and single-use systems. The WaveOne Gold is created using proprietary thermal processing obtained by heating the NiTi file and then cooling it slowly; different from production of M-Wire, a pre-manufacturing thermal processing, which is attributed to improvement instrument's elasticity [5]. The Reciproc Blue results from creative thermal processing that produce an instrument with a blue surface.…”