치과용 합금의 부식 특성에 관한 연구

Abstract

For the aesthetic and functional restoration of edentulous patients, recently dental implants have been used widely. Dental implants and restorative alloys are required with the high corrosion resistance. Therefore, Ti and its alloys have been used as implant materials and gold, silver, Ni-Cr and Co-Cr alloys as dental restorative materials due to their high corrosion resistance. However, they can be corroded in the oral cavity that is very complicated environment. In this study, Ti G2 and G3, gold, silver, Co-Cr and Ni-Cr alloys were investigated for their corrosion resistances and phenomena. Potentiodynamic and potentiostatic tests(open circuit potential and current density at -250, 0 and 250 mV(SCE)) were performed in artificial saliva at 37℃. Corrosion of gold and silver alloys did not occur in artificial saliva due to their immunity in this environment. Co-Cr, Ni-Cr and pure Ti exhibited the high corrosion resistance by their own passivity. Gold, silver and Ti G2 exhibited the highest corrosion resistance, Ni-Cr alloy and Ti G3 did the relatively high corrosion resistance, and Co-Cr alloy did the low corrosion resistance. The open circuit potentials of gold, Ti G2, Ni-Cr and silver alloys were about 50, 20, 0 and -60 mV(SCE), respectively. The open circuit potentials of Ti G3 and Co-Cr decreased with the immersion time. In the potential loading of -250mV, cathodic current flowed to all samples, although the absolute values were different. In the potential loading of 0mV, cathodic current in the potential loading of 250mV. If the pure Ti is used as dental implant in the oral cavity, gold and silver alloys are considered to minimize the adverse effects by galvanic corrosion, but the galvanic corrosion as well as the localized corrosion such as pitting or crevice can be occurred in Co-Cr alloy.