In Vitro Comparison of Cyclic Fatigue ResistanceofRevo-s& One- Shape inStraight and Curved Canals

Abstract

The aim of this study was to evaluate the cyclic fatigue resistance of OneShape file and SU file fabricated from traditional NiTi alloy under the effect of angle of curvature and number of usage. A total of forty files are tested. Samples were divided into two main groups according to the file type, then each group was divided to two sub-groups according to the angle of curvature, each sub-group was divided to two sub-divisions according to number of usage. Cyclic fatigue device was constructed to this study, the main metal block contains two canals having curvature 6o and radius of curvature 5mm .files were allowed to rotate inside these canals until fracture and the time to fracture was recorded then number of cycles to failure were calculated. Statistical analysis was performed with three-way analysis of variance and turkey test for individual comparison(confidence level of p<0.05).Fractured surfaces of broken instruments were observed under scanning electron microscope for any defect or deformations observed after testing.

Regarding the file type OneShape file showed cyclic fatigue resistance significantly higher than SU file (p<0.001). Regarding the angle of curvature, all files at (30-35) showed significant fatigue resistance than (40-45). Regarding the number of time to use, all files at one time showed higher cyclic fatigue resistance than three time use.