Chemical characterization of selected high copper dental amalgams using XPS and XRD techniques

The study was carried out to analyze some dependencies between the composition of seven high copper dental amalgams and mercury release behavior, as well as oxygen reactivity of metallic elements. Chemical comparative analysis of selected dental amalgams was carried out using X-ray photoelectron spectroscopy (XPS) technique and X-ray diffraction (XRD) method. The X-ray powder diffraction measurements revealed two main phases for measured amalgams: γ1-(Ag2Hg3) and η'-(Cu6Sn5). The amount of mercury obtained by the XPS method was lower than the value quoted in the manufacturer's literature, which suggested evaporation of mercury under the UHV conditions. A linear decrease of oxygen and carbon contamination with the growing amount of Cu and Ag was observed. The XPS analysis showed that a high Sn concentration caused less resistance to oxidation. Some of the amalgams contained some extra elements, such as Bi, In, and Zn. All samples contained lead in metallic state and oxides. The amount of Ag, Cu, Sn ingredients determines the main properties of high copper amalgams and plays an important role in mercury evaporation. High tin concentration combined with the presence of smaller amounts of silver and copper (high Sn/Ag ratio) may influence the increase of mercury vaporization.