Corrosion resistance of dental alloys in pseudo-oral environment

The corrosion resistance of dental alloys was investigated by taking anodic polarization measurements in 1 mass%-lactic acid, artificial saliva, and c ell-culture medium solutions. The role of alloying elements in the passive film that formed on the dental alloys by the anodic polarization was examin ed using X-ray photoelectron spectroscopy. The quantity of metals released from the dental alloy into the 1% lactic acid solution at each anodic poten tial was compared. In the anodic polarization curves fur the Au and Au-Ag-P d alloys, the current density tended to decrease with higher Au content. In the Ag alloy, the current density sharply increased in the 1 mass%-lactic acid solution. On the other hand, the passivity zone was slightly seen in t he artificial saliva and Eagle's medium solutions. Amalgam had a Low open-c ircuit potential, and a passivation peak was seen. The peaks of the Au4f an d Ag3d orbital were high in the surface of the passive film formed oil the Au and Au-Ag-Pd alloys by anodic polarization in the artificial saliva solu tion. SnO2 and In2O3 peaks were observed in the passive film formed on the Ag alloy. SnO2 and CuO peaks were seen in the passive film on amalgam surfa ce. In the Au and Au-Ag-Pd alloys, Cu was released most in the low potentia l region less than 1.0 or 0.5 V us. SCE, respectively. For the Ag alloys, Z n release was most, and Ag, Sn and In were also released. In amalgam, Sn re lease increased with higher anodic potentials. Cu release also increased at potentials over 0 V. Ag and Hg release increased from potentials over 0.5 V. Considering that the electrode potential measured in the pseudo-oral env ironment is a maximum of 0.2 V, it is important to examine the effect of Cu and Ag releases far the Au and die Au-Ag-Pd alloys, Zn release for the Ag alloy, and Sn and Cu releases for amalgam.