Influence of Temperature on the Cyclic Fatigue Resistance of Reciproc Blue Instruments.

AIM: To evaluate the cyclic fatigue resistance of Reciproc blue (RB) 40/0.06 instruments tested at room temperature (20 degrees +/- 0.5 degrees C) and at body temperature (37 degrees +/- 0.5 degrees C) in a simulated stainless steel canal. MATERIALS AND METHODS: Twenty-four new RB 40/0.06 instruments were randomly divided into two groups (n = 12) according to the temperature used. Dynamic fatigue testing was performed using an artificial stainless steel canal with a 60 degrees curvature angle and a 5-mm radius of curvature. The temperature was controlled throughout the experiment with an underwater thermometer and a thermostat. The data were analyzed descriptively using the IBM SPSS 23.0 program, considering p < 0.05. RESULTS: The time to fracture of the RB instruments differed significantly between the two temperatures (1083.82 seconds at 20 degrees C and 403.80 seconds at 37 degrees C). No significant differences were found in fragment size. CONCLUSION: An increase in temperature reduces the cyclic fatigue resistance of RB 40/0.06 instruments. The results of the study suggest that an intracanal cooling system can be favorable to the fracture resistance of the tested instruments. CLINICAL SIGNIFICANCE: A cooling system of the root canal system is important in endodontic as it favors the cyclic fatigue resistance of Ni-Ti instruments.