Influencia del diseño de la sección transversal sobre la resistencia a la fatiga cíclica de dos instrumentos endodónticos de Níquel- Titanio en canales artificiales con Curvatura de 60°: Estudio In Vitro

Abstract The unexpected fracture of nickel-titanium rotating instruments (NiTi) during endodontic treatments represents a critical complication, especially in curved ducts where cyclic fatigue constitutes one of the main causes of failure. This situation has motivated the search for improvements in the geometric design of the instruments, particularly in the cross-section, to increase their resistance and clinical safety. This research aims to evaluate the influence of the cross-sectional design of two Nickel Titanium endodontic instruments on the resistance to cyclic fatigue using artificial ducts with a curvature of sixty degrees, by measuring the time it takes the instrument to break. A comparative and cross-sectional in vitro investigation was carried out with 40 files categorized into two groups: AF™ F-One ("S" section) and JIZAI (rectangular eccentric section). Each instrument was subjected to continuous rotation at 500RPM under standardized circumstances until its breakage, with measurements taken for the number of cycles and the duration in seconds. The findings indicated that the JIZAI file exhibited an average of 2238.33 cycles to fracture and an average duration of 268.6 seconds, while the AF™ F-One demonstrated 787.83 cycles and 94.47 seconds. The differences were statistically substantial (p < 0.001), demonstrating the best performance of the JIZAI system. This benefit is attributed to its optimized geometric configuration and sophisticated thermal processing, which provide a more effective distribution of internal stresses, identifying that JIZAI demonstrated superior resistance to cyclic fatigue, which makes it a safer and more effective option for instrumentation in curved channels.