TiN 및 ZrN 코팅이 교정용 브라켓과 와이어의 표면특성에 미치는 영향

Abstract

The dental orthodontic wire requires good mechanical properties, such as elastic strength and frictional resistance, combined with a high resistance to corrosion. The purpose of this study was to investigate the effects of TiN and ZrN coating on corrosion resistance and physical property of orthodontic bracket and wire using various instruments. Bracket and wire(round type and rectangular type) were used, respectively, for experiment. Ion plating was carried out for bracket and wire using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen was observed with field emission scanning electron microscopy(FE-SEM), energy dispersive x-ray spectroscopy(EDS), atomic force microscopy(AFM), vickers hardness tester, and electrochemical tester. The results were as follows.: 1. The surface of TiN and ZrN coated bracket and wire were more smooth than that of other kinds of non coated bracket and wire. 2. The hardness of TiN and ZrN coated surface showed higher than that of non coated surface. 3.The corrosion potential of the TiN coated bracket and wire was comparatively high. The current density of TiN coated bracket and wire was smaller than that of non-coated bracket and wire in 0.9% NaCl solution. Pit nucleated at angle of bracket slot and at scratch of wire. 4. The pitting corrosion resistance｜Epit-Erep｜ increased in the order of ZrN coated(300 mV), TiN coated(120 mV) and non-coated wire( 0 mV). 5. From cytotoxicity test, the optical density of gingiva and L929 cell in the case of the TiN and ZrN coated wire was higher than that of gingiva and L929 cell in the case of non-coated wire and control group. The TiN and ZrN coated wire can be considered non cytotoxic. It is considered that the TiN and ZrN coated film which would prevent bracket and wire from corroding can be applicable to orthodontic system and confirmed that TiN and ZrN film act as inhibitor against corrosion on surface between bracket and wire due to decrease of mechanical defects.