Temperature-Dependent Effects on Cyclic Fatigue Resistance in Three Reciprocating Endodontic Systems: An In Vitro Study

This study aimed to analyze the effect of 1% sodium hypochlorite (NaOCl) solution at different temperatures on endodontic file resistance to cyclic fatigue. A total of 90 files, Reciproc NiTi M-Wire (R) (REC) (n = 30), WaveOne Gold (R) (WOG) (n = 30), and Reciproc Blue (R) (RB) (n = 30) were activated under constant irrigation with 1% NaOCl at 5, 37, and 60 degrees C in a stainless-steel artificial canal (curvature angle = 60 degrees; radius = 5 mm). The time to the fracture and the maximum and minimum load were recorded for each instrument, and data were subjected to statistical analysis. A higher number of cycles to fracture at 5 degrees C was observed between WOG and RB compared to the REC system (p < 0.05). The RB files were more resistant to cyclic fatigue fracture at 60 degrees C than WOG and REC (p < 0.05). No statistically significant differences were found between the mean values of the three file types used at 37 degrees C. The high temperature of NaOCl significantly affects the lifespan of endodontic files, making them more prone to fractures due to cyclic fatigue. The files manufactured with heat treatment showed a longer life than M-wire reciproc files.