Corrosion of a fluorocanasite dental glass-ceramic

We investigated the corrosion behavior of a fluorocanasite glass-ceramic developed as a dental ceramic. Our investigation was aimed at determining the major corrosion processes. A series of water-dominated static corrosion tests was conducted for up to 14 days. In these tests, the pH of the leachates increased, along with the concentrations of Na, Al, Si, K, and Ca after one day of reaction. The concentrations of K and Na, normalized to their concentrations in the glass-ceramic, were higher than the normalized concentrations of the other elements. These results are consistent with an exchange of H+ and K+ or Na+ in the glass-ceramic as an important corrosion reaction. Microstructural examination of the reacted glass-ceramic showed that the glass phase is more affected by corrosion than the crystalline fluorocanasite. In addition, corrosion is most prevalent near the edge of the glass-ceramic body where large glass regions and crystals are present. We propose that exchange of H+ for K+ and Na+ in the glass phase was the dominant reaction in the corrosion of this glass-ceramic during these short-term tests. Changes in the chemistry of the glass phase might lead to a decrease in this rate of this exchange. In addition, if changes in the processing of this material could eliminate the large glass regions, then the corrosion behavior of the material might be improved.