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 quicker and easier treatment times and more thorough irrigation of the root canal system. Despite the advantages of the NiTi files, instrument separation still remains a major concern. The purpose of this study was to compare the cyclic fatigue resistance and the fragment length after clinical use of, WaveOne Gold (WOG, Dentsply, Maillefer, Ballaigues, Switzerland) One Curve (OC, Micro Mega, Besancon, France) and Reciproc Blue (RB, VDW, Munich, Germany) single-file NiTi systems. A total of 120 patients who required endodontic treatment to first or second mandibular molars. Patients were randomly divided into three file groups (patientn=40) and root canals were prepared with WOG, OC, or RB single file systems. Each group consists of 2 subgroups: first use (filen=10, patientn=10) and third use of file (filen=10, patientn=30). In control group, the files were subjected to cyclic fatigue test without use (filen=10). Each file except the control group was autoclaved before tested. The cyclic fatigue resistance of files was evaluated by groove method.The data wasevaluated by Oneway ANOVA analysis, Games&Howell Post-Hoc analysis, repeated measurements analysis and Weibull reliability analysis. In consider the control and 1st use group, statistically significant difference were found among files (p<0.05), however, RB showed the highest value of fracture time. In 3rd use group, OC and RB files showed significantly high value of fracture time rather than WOG (p<0.05). Based on the pairwise comparisons within files, WOG showed significant difference between control-3rd use and 1st-3rd use groups. OC showed significant difference between control-1st use and control-3rd use groups. However, RB showed significant difference between control and 1st use groups. Overall, RB files showed the highest value of fracture time in 1st use. There was statistically significant difference among the groups considering the fragment length. In conclusion, RB files showed higher value of fracture time than OC and WOG in control, 1st and 3rd use groups. However, the lowest value of fracture time was seen in 3rd use of WOG. Within the limitations of this study, it should be emphasized thatRB can be use until three root canal treatment safely. Key Words:cyclic fatigue, repeatedly used, nickel-titanium single file systems, reciprocation, rotation