Discoloration and corrosion resistance of Tin-coated orthodontic appliances produced by Ion-plating method

Kim, Jin Hee; Kwon, Oh Won; Choi, Young Yun

Abstract

The purpose of this study was to estimate the possibility of practical application of TiN ion-plating method on orthodontic appliances. TiN was coated on the surface of orthodontic stainless steel roll band by means of ion-plating method, and colorimetric properties of its obtained TiN film were investigated by using color analyzer. Also its corrosion and discoloration properties were compared with those of non ion-plated stainless steel roll band by using immersion test, which was done in 1N HCl solution for 10 days. Both weight changes and surface corrosion appearances of specimens for each day were respectively investigated by using electronic weighing machine and SEM(Scanning Electron Microscope). The discoloration degress of TiN-coated specimens immersed in 1N HCI solution were investigated by using color analyzer and then judged by N.B.S.(National Bureau of Standard) Unit. The results of this study were summarized as follows. TiN ion-plated films showed the hue of 5Y, the value of 7, and the chroma of 3 by Munsell notations. The weight losses and surface changes of TiN ion-plated specimens immersed in 1N HCI solution were less than those of non ion-plated specimens. It was shown, therefore, that the corrosion resistance was significantly improved by TiN ion-plating. The discoloration degrees of non ion-plated specimens were too significant to be examined by color analyzer, while those of TiN ion-plated specimens were slight when judged by N.B.S. Unit. It was also apparent, therefore, that the anti-discoloration property was significantly improved by TiN ion-plating.