Comparison of cyclic fatigue resistance of three different single-file systems after clinical use

Nickel titanium (NiTi) rotary files have drastically altered the treatment protocol in endodontics, allowing for faster and easier preparation and more thorough irrigation of the root canal system. Despite the advantages of the NiTi files, instrument separation still remains a major concern. The aim of this study was to compare the cyclic fatigue resistance of three different single-file NiTi systems after clinical use: WaveOne Gold (WOG, Dentsply Maillefer, Ballaigues, Switzerland), One Curve (OC, Micro Mega, Besancon, France), and Reciproc Blue (RPC Blue, VDW, Munich, Germany).

A total of 120 patients requiring endodontic treatment to first or second mandibular molars, were randomly divided into three groups (patient n = 40) and root canals were prepared with WOG, OC or RPC Blue. Each group consists of 2 subgroups: first use (file n = 10, patient n = 10) and third use of file (file n = 10, patient n = 30). In control group, files were subjected to cyclic fatigue test without use (file n = 10). Cyclic fatigue resistance of files was assessed by groove method. The data was evaluated by two-way ANOVA, Games & Howell post hoc and Weibull reliability analyses (p < .05).

RPC Blue files showed the highest failure time value in all groups. In third use group, OC and RPC Blue files showed significantly higher failure time values compared to WOG files (p < .05). In general, RPC Blue files show the highest values in terms of number of cycles to fracture (NCF) in all groups, while OC and WOG files follow RPC Blue files respectively. There was statistically significant difference among groups considering the fragment length (p < .05).

Within the limitations of this study, RPC Blue files exhibited highest cyclic fatigue resistance after clinical use.