Comparative Evaluation of Cyclic Fatigue and Corrosion Resistance of Three Different Nickel-Titanium Instruments
Abstract
Methods: This study was carried out in two stages. In the first one, a total of 120 Ni-Ti rotary instruments (25/.04 taper) from 3 brands (HeroShaper, RaCe, and TF) were selected. Sixty of them were anodized then all of them were tested in simulated root canals with two different curvatures. The time until fracture was recorded, and the number of cycles was calculated for each group. The second stage; the effect of anodization on corrosion resistance was assessed. The file groups tested in 5% NaOCl solution at 37° C. Data were subjected to The Mann-Whitney U test. The significance level was set at P= 0.05.
Results: There was a statistical difference among the rotary systems in terms of cyclic fatigue. Among the file types, TF instruments were the most resistance to cyclic fatigue and RaCe instruments had the lowest results. The effect of anodization process was different among file groups.
Conclusion: Within the limits of this study, the increase in canal curvature reduces the life of the rotary instruments. While the anodization process did not change cyclic fatigue in all file groups in 20° curved canals, it reduced the wear life of RaCe and HeroShaper files and extended the wear life of TF files in canals with 37° curved canals.
Keywords
Anodozation, canal curvature, cyclic fatigue, HeroShaper, RaCe, Ni-Ti, rotary systems files, twisted file
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