Influence of Temperature on Cyclic Fatigue Resistance of ProTaper Gold and ProTaper Universal Rotary Files

Introduction: The aim of this study was to evaluate the cyclic fatigue resistance of ProTaper Universal (PTU; Dentsply Maillefer, Baillagues, Switzerland) and ProTaper Gold (PTG, Dentsply Maillefer) nickel-titanium rotary files at room and intracanal temperatures.

Methods: A total of 120 files were used to test the cyclic fatigue resistance of PTU (S1 and F2) and PTG (S1 and F2) in an artificial canal at room temperature (20°C) and at intracanal temperature (35°C). The number of cycles to failure and the fracture length of the fragment were recorded, and data were subjected to statistical analysis.

Results: PTG registered no differences in fatigue life between the 2 temperatures tested (P > .05), whereas PTU showed a statistically significant reduction in fatigue life at intracanal temperature compared with room temperature (P < .05). PTG instruments exhibited a statistically higher resistance to cyclic fatigue than PTU instruments both at room and intracanal temperatures (P < .05). There were no statistically significant differences among the fracture length of separated instruments (P > .05).

Conclusions: Intracanal temperature influenced the cyclic fatigue resistance of instruments produced with traditional nickel-titanium, whereas it did not influence the fatigue life of instruments produced with gold heat treatment. Gold heating treatment enhances the resistance to cyclic fatigue of ProTaper instruments.