Effect of Different Temperatures on Flexural Cyclic Fatigue Resistance of 2Shape and OneShape Rotary Endodontic Instruments

Objectives: The aim of the present study was to evaluate the effect of the different temperatures on the flexural cyclic fatigue of 2 Shape and OneShape rotary endodontic files.
Materials and Methods: Forty-rotary endodontic files were divided according to the type of instrument used and the surrounding temperature (n=10); 2Shape and OneShape rotary endodontic files rotated in a custom made simulated canal model block fixed to a beaker containing water with temperature adjusted to either 37 °C or 60 °C. Time was recorded from the beginning of rotation until the fracture was detected, then the number of cycles to failure (NCF) and the length of the fractured segment (FL) were evaluated. Two representative samples were photographed under scanning electron microscopy. Two-way Analysis of Variance (ANOVA) was used to study the effect of the type of instrument used and temperature on the number of cycles to failure and the length of the fractured segment.
Results: 2Shape rotary endodontic files used at 37° C showed statistically significant highest mean of number of cycles to failure compared to 2Shape at 60°C (P<0.001), then OneShape used at 37°C, and finally the OneShape used at 60 °C (P<0.011).
Conclusions: 2 Shape showed more resistance to flexural cyclic fatigue than OneShape, and high temperature seemed to have a reducing effect on the flexural cyclic fatigue resistance of the both tested rotary endodontic instruments.
Objectives: The aim of the present study was to evaluate the effect of the different temperatures on the flexural cyclic fatigue of 2 Shape and OneShape rotary endodontic files.
Materials and Methods: Forty-rotary endodontic files were divided according to the type of instrument used and the surrounding temperature (n=10); 2Shape and OneShape rotary endodontic files rotated in a custom made simulated canal model block fixed to a beaker containing water with temperature adjusted to either 37 °C or 60 °C. Time was recorded from the beginning of rotation until the fracture was detected, then the number of cycles to failure (NCF) and the length of the fractured segment (FL) were evaluated. Two representative samples were photographed under scanning electron microscopy. Two-way Analysis of Variance (ANOVA) was used to study the effect of the type of instrument used and temperature on the number of cycles to failure and the length of the fractured segment.
Results: 2Shape rotary endodontic files used at 37° C showed statistically significant highest mean of number of cycles to failure compared to 2Shape at 60°C (P<0.001), then OneShape used at 37°C, and finally the OneShape used at 60 °C (P<0.011).
Conclusions: 2 Shape showed more resistance to flexural cyclic fatigue than OneShape, and high temperature seemed to have a reducing effect on the flexural cyclic fatigue resistance of the both tested rotary endodontic instruments.