Abstract
Ag-In alloy cast crowns were removed from the oral cavities of six patients and their tarnish films were analyzed by ESCA.Thickness of the films formed on the alloy surfaces was ranged from 1, 500 to 12, 000Å, and the alloy surface became darker with increasing film thickness.The tarnish films included both In and Zn oxides.The films did not contain sulfides or chlorides of alloy elements but Ag was presented in a metallic state.The Zn oxide in the films was ZnO and In oxide was not In2O3 which is the most stable oxide of In.Tarnish of Ag-In alloy in the oral environment arose from the formation of In and Zn oxides on the alloy surface.
