Tarnish resistance evaluation of experimental Pd-free Ag-Au-Pt-Cu dental alloys

Abstract

This study evaluated the tarnish resistance of eight experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.1% Na2S aqueous solution at 37°C. Color measurements of the plate samples were made using a computerized spectrophotometer before and after immersion in the test solution for up to 72 hours. Tarnish discoloration was evaluated using the color difference vector, ΔE*, in the CIELAB color space. Microstructural observation of each sample through an optical microscope revealed the matrix phase as the major constituent and second-phase small grains in the matrix phase. Selective tarnish discoloration occurred in the matrix, and fractional area of the matrix to the whole surface area was influenced by the sum of Au and Ag concentrations. The ΔE* value significantly decreased with increasing Au/(Au+Ag) atomic ratio. In conclusion, the Au/(Au+Ag) ratio in an alloy and the fractional area of the matrix were found to be primary and auxiliary factors affecting the tarnish resistance of the experimental alloys.

Fractals in dentistry

“…Takuma et al [43] mentioned the use of FD to obtain the fractional area of the matrix to the whole surface in a study of the tarnish resistance of Pd-free Ag-Au-Pt-Cu dental alloys. Mangano et al [44] characterized the surface of Ti6Al4V alloy model dental root implants made with direct laser fabrication.…”

Corrosion resistance evaluation of Pd-free Ag-Au-Pt-Cu dental alloys

“…In recent years, Pt was found to wield twofold advantages over Pd in terms of stability in price and supply 22) . Hence, we developed Pd-free Ag-Au-Pt-Cu alloys and investigated their tarnish resistance 23) and cell toxicity.…”