TORSIONAL RESISTANCE TESTS ON Ni-Ti FILES HAVING THE SAME SHAPE BUT DIFFERENT PHASE
2017 年 8 巻 1 号 p. 34-40
詳細
2017 年 8 巻 1 号 p. 34-40
The purpose of this study was to investigate the resistance to torsional stress and cyclic fatigue of R-phase Ni-Ti files experiencing different phase-transformation temperatures with identical geometric characteristics. In the cyclic fatigue failure test, the values were SILK 5481±1307.18 and SILK-N (before heat-treatment of SILK) 2922±702.55, respectively. SILK was significantly greater than SILK-N (p < 0.01).
In the torsional torque test, the values were SILK 57.24±2.65 gfcm and SILK-N 58.58±3.15 gfcm, respectively, and there were no significant differences.
In the torsional bending test, SILK was 514.91±84.78° and SILK-N was 521.63±78.13°, and there were no significant differences. In scanning electron microscope examination of factors causing fatigue fracture, the dimpling percentages for SILK and SILK-N were 7.25±3.02 and 5.69±2.76, respectively, and there were no significant differences. The results of the present study suggest that, at clinical temperatures, the R-phase Ni-Ti files have a higher cyclic fatigue resistance than those with the austenite phase.
