Microstructural analyses of two high noble gold-platinum alloys before and after conditioning in a cell culture medium

Abstract

Microstructures of two high noble experimental Au-Pt alloys were compared before and after conditioning for biocompatibility, in order to identify phases and microelements responsible for the alloys' corrosive behaviour. Microstructural characterization was carried-out by optical and scanning electron microscopy, in addition to energy dispersive X-ray analysis. X-ray diffraction was applied to determine the phases' composition and their contribution in the alloys. Additionally, simultaneous thermal analysis was used to identify the temperatures of phase transformations. An overall assessment before conditioning showed that Au-Pt I is a two-phase alloy containing a dominant Au-rich α 1 phase and a minor Pt-rich α 2 phase, while the Au-Pt II alloy contains in addition three minor phases: AuZn 3 , Pt 3 Zn and Au 1.4 Zn 0.52 . The highest content of Zn (up to 6.76 wt.%) was detected in the Pt 3 Zn phase. After RPMI cell culture medium conditioning, the Pt 3 Zn and AuZn 3 phases disappeared, suggesting that they are predominantly responsible for Zn loss and the lower corrosive stability of the Au-Pt II alloy.

Ageing of Advanced Biomaterials

“…Many published works describe the microstructure and properties of base and noble dental alloys in the as-cast state and after heat treatment, and often include the simulation of relevant ceramic firing cycles. However, there are only a few published studies that directly examine the ageing of dental alloys (noble metals only) at intraoral or room temperature (Rudolf et al, 2010).…”