Effect of Heated Irrigating Solutions on the Cyclic Fatigue Resistance of Reciprocating Endodontic Files

Objectives: The aim of this study was to evaluate the effect of heated irrigating solutions on the cyclic fatigue resistance of reciprocating endodontic files. Materials and Methods: Reciproc Blue, ProDesign S and X1-Blue files were immersed in the irrigating solutions 5.25% NaClO and 2% chlorhexidine digluconate gel heated in oven at 37ºC for 10 min. In same conditions, saline solution was considered as control.  The following groups (n=15) were considered: RSs (Reciproc Blue + saline solution); RNa (Reciproc Blue + 5.25% NaClO); RCd (Reciproc Blue + 2% Chlorhexidine digluconate gel); PSs (ProDesign S + saline solution); PNa (ProDesign S + 5.25% NaClO); PCd (ProDesign S + 2% Chlorhexidine digluconate gel; XSs (X1-Blue + Saline solution); XNa (X1-Blue + 5.25% NaClO) and XCd (X1 Blue + 2% Chlorhexidine digluconate gel). Cyclic fatigue test was performed in a device with a 60 degrees curved canal and 5 mm radius immersed in water at 37ºC. The time for file failure was recorded in seconds to calculate the number of cycles to fracture (NCF). Data were submitted to ANOVA followed by Tukey's test (α=0.05%) comparing split plots (SPSS 26.0). Results: There was no statistically significant difference for NCF between irrigating solutions and control in all file types. ProDesign S showed greater and significant difference when compared to Reciproc Blue and X1 Blue in all irrigating solutions and control. Conclusions: NCF value in each file type was not influenced by the solutions. Among file types, the NCF value was higher for ProDesign S and lower for X1-Blue in all solutions. Clinical Relevance: Heated irrigating solutions is not a relevant factor in relation to fracture resistance of reciprocating endodontic files; however, the fracture was influenced by the file types.