온도변화가 교정용 니켈-티타늄 호선의 상-변태에 주는 영향 = The Effects of Temperature Changes on the Phase Transformation of Orthodontic Nickel-Titanium Wires

다국어 초록 (Multilingual Abstract)

The purpose of this study was to evaluate the change of phase transformation and mechanical properties of orthodontic Ni-Ti wire by temperatures changes (0 ℃, 20 ℃, 37 ℃ and 60 ℃) using three-point bending tests and to investigate the phase transformation behavior by microstructure analysis and X-ray diffraction in greater detail. The transition temperature range (TTR) of orthodontic Ni-Ti wires was analysed by DSC for the reference of proportion of martensite to austenite matrix. From this study the following results were obtained. In SM group, as the temperature decreased to 20 ℃ and 0 ℃, superelasticity loop showing at 37 ℃ in load-deflection curve disappeared and the critical load of stress induced martensite transformation decreased (p<0.01). In SE group, the load increased as the temperature increased as the temperature increased under certain temperature (p<0.01). From the microscope, the proportion of stripe-shaped martensite plate to austenite matrix was higher in NEO, active martensite alloy, than OPTI, the active austenite alloy. The (002) peak indicating martensite phase clearly appeared when the temperature decreased to -20 ℃ in NEO from the X-ray diffraction spectra. This study indicated that mechanical properties of orthodontic Ni-Ti wires were substantially affected by temperature and we could expect the biological response in periodontal ligament by load fluctuation of wires tied in bracket induced by temperature variation.