The effect of cooling Reciproc instruments prior to preparation on cyclic fatigue resistance at simulated body temperature

Abstract

Purpose: This study aimed to examine the effect of cooling Reciproc endodontic files prior to preparation on their cyclic fatigue life at simulated body temperature. Methods: Sixty-four Reciproc R40 files were randomly split into 4 groups (n = 16), as follows: control, cooling at ?50°C, cooling at ?16°C, and cooling at ?80°C groups. The files were used in a simulated metal canal with a curvature of 90° and a radius of 3-mm. The metal block was submerged in a water tank adjusted to a temperature of 37°C. The time to file fracture and the length of the broken fragment were measured and recorded. The data were analyzed using a Kruskal–Wallis H test. Results: The time to fracture was significantly lower in the control group compared to the cooling groups (p< 0.05). No differences in the time to fracture (p> 0.05) were observed between the cooling groups, and all groups exhibited similar length of the fractured fragments (p> 0.05). Conclusion: Within the limitations of this study, it can be concluded that cooling Reciproc R40 files using different methods prior to preparation improves its cyclic fatigue resistance.