Cyclic fatigue resistance of two NiTi rotary instruments after blue heat treatment

作者：Rodríguez-Delgado I, Salazar-Vázquez JM, Flores-Treviño JJ, Martínez-García MG, Diabb-Zavala JM, De La Garza-Ramos MA · 发表于：Journal of clinical and experimental dentistry · 年份：2026 · DOI：10.4317/jced.63881 · 被引用次数：20

BACKGROUND: This study evaluated the cyclic fatigue resistance of two blue heat-treated rotary instruments. Thirty files (15 Eflex Blue and 15 BlueShaper) activated by an E-CONNECT motor at 350 RPM with a 2.5 N torque were evaluated. MATERIAL AND METHODS: A stainless-steel device with three different curvatures (25°, 45°, and 90°) was fixed to a SHIMADZU tensile testing machine to measure cyclic fatigue. The instruments were placed on the motor at a constant speed, then on the testing device; the time to each instrument's fracture was recorded. Tension, time, and instrument deformation were measured. Data were analyzed using the Shapiro-Wilk and Kruskal-Wallis tests at a 5% significance level. RESULTS: Eflex Blue files demonstrated superior tensile strength and stability over time, particularly at a 25° curvature (p < 0.05). Performance was comparable between the two files at 45° and 90° curvatures, with no significant differences in deformation percentage. CONCLUSIONS: Eflex Blue files demonstrated greater cyclic fatigue resistance than BlueShaper, especially at smaller curvatures (25°). Although both systems exhibited similar deformation rates, the fracture resistance of both files decreased as curvature increased, reaching a critical threshold at 90°.