Some Properties of Au-Containing Dental Amalgam

Abstract

Conventional dental alloy, mostly Ag₃Sn, has been modified by substituting 10 wt% Au for as much Ag. A spherical-particle, rapidly quenched alloy powder was produced by spraying the melt into a reducing atmosphere.

Amalgam prepared from this alloy has improved physical and chemical properties, especially corrosion resistance. Tensile strength was about 9000 psi, creep about 0.94%, and dimensional change about +23 μm/cm. Dissolution was essentially zero at -0.25 V in an artificial saliva.

X-ray diffraction showed γ₁ and γ₂ peaks in the freshly prepared amalgam but only γ₁ after storage at body temperature for about 2 weeks. Metallographic specimens showed a ring containing a high concentration of Au and Sn around each alloy particle in the amalgam.