Ion release from metal-ceramic alloys in three different media

The aim of this in vitro study was to assess the effect of pH changes on ion release of metal-ceramic dental casting alloys. Samples from four commercially available alloys (Wirobond C, Wiron 99, Rematitan CP-Ti grade 1, and PontoStar) were prepared and polished. Ion release of alloys subjected to three different pH media (artificial saliva of pH 2.3, pH 6.5 and 0.9% saline solution of pH 7.3) for periods of 7, 15, 30, and 60 days were assessed by means of atomic absorption spectroscopy. Microscopic changes on surfaces of metallic samples before and after immersion were compared by scanning electron microscopy. ANOVA was used for statistical analysis of results. For all ions, pH and period interactions were statistically significant: highest amount of ion release occurred after 60 days of immersion regardless of pH value. For every alloy, ion release results were highest in artificial saliva of pH 2.3 and lowest in 0.9% saline solution. It was concluded that ion release from alloys was pH-dependent.