The effect of multiple sterilization on cyclic fatigue resistance of nickel-titanium rotary file systems produced by different processes

The aim of our study is to compare the cyclic fatigue resistance of EndoArt Touch Gold and EndoArt Touch Blue branded rotary file systems produced with different processes and to examine the effect of multiple sterilization on the cyclic fatigue resistance. In this in-vitro study, control and sterilization groups of 2 different Ni-Ti rotary file systems were formed. A total of 100 Ni-Ti files, 25 in each group; It was used statically in an artificial canal made of stainless steel with an internal diameter of 1.5 mm, a curvature of 60° and a radius of 5 mm. The cyclic fatigue tests of the files belonging to the control group were performed and the mean breakage times were determined. The times corresponding to 25%, 50% and 75% of these average breaking times were determined. Sterilization group files were used in the cyclic fatigue test setup up to 25%, 50% and 75% of the mean breakage times, respectively, and the operation was stopped at these points and sterilization with autoclave was applied. After 75% of the mean break time at the last autoclave, the files were used until they broke in the cyclic fatigue test setup. The breaking length of all files was measured; The time to breakage was determined as seconds (sec). The conformity of the data to the normal distribution was evaluated with the Shapiro-Wilk test and the Kruskal-Wallis test was used for analysis. According to the comparison results, a significant difference was found between the EndoArt gold sterilization group and the EndoArt blue sterilization group, and between the EndoArt gold control group and the EndoArt blue control group (p<0.05). When the broken piece lengths are examined; While the difference between the EndoArt blue sterilization group and the EndoArt blue control group was significant (p<0.05); No statistically significant difference was found between the other groups. It was determined by SEM analysis that the fractures occurred as a result of cyclic fatigue. As a result, the file system with the highest cyclic fatigue resistance was determined as EndoArt Blue. The sterilization had no significant effect on cyclic fatigue resistance.