Comparison of cyclic fatigue resistance between heat-treated and conventional retreatment files

Abstract

Objectives: To compare the cyclic fatigue resistances of MicroMega Remover, EndoArt, and ProTaper nickel-titanium retreatment files when used in curved artificial canals. Methods: A total of 45 new C-wire Remover, controlled-memory wire EndoArt D2, and nonheat-treated NiTi ProTaper D2 retreatment files, 15 per group, were tested in a stainless-steel block containing an 18-mm-long artificial canal with curvature in the apical third, an inner diameter of 1.5 mm, a curvature angle of 60°, and a radius of curvature of 5 mm. The experimental system was filled with distilled water, and the ambient temperature was kept constant at 35±1°C. The retreatment files were rotated until fracture to calculate the number of cycles to failure. The length of each fractured fragment was recorded. The number of cycles to failure and the fragment length values were analyzed using one-way analysis of variance (ANOVA) and Tukey post-hoc tests. The statistical significance level was set at p<0.05. Results: The group with the highest number of cycles to failure values was EndoArt D2 (1401.33±279.00), followed by MicroMega Remover (950.07±195.84) and ProTaper D2 (341.87±48.12), with a statistically significant difference between all file systems tested (p<0.05). No difference was observed among the retreatment files regarding the lengths of fractured fragments. Conclusions: The EndoArt D2 file exhibited greater cyclic fatigue resistance than the MicroMega Remover and ProTaper D2 files.

Keywords

• cyclic fatigue
• endodontic file
• retreatment
• root canal preparation