Novel ion-exchangeable nepheline glass-ceramics for dental application

Ion exchange of a glass-ceramic system with a specific crystalline phase can lead to materials with superior chemical, physical and mechanical properties. The aim of this study is to characterize newly synthesised nepheline glass-ceramics for dental restorative applications. Four novel experimental glasses based on the nepheline composition were ground into fine powders and then sinter-crystallized into monolithic glassceramics. The developed glass-ceramics were characterized before and after ion exchange in a potassium nitrate bath using X-ray diffraction, EDX-SEM, and biaxial flexural strength, hardness and solubility testing in accordance with ISO-6872. The ion exchange process of nepheline containing glass-ceramic Al20 increased the characteristic strength by more than 163 % compared to the starting value. The experimental glass-ceramics increased in strength after ion exchange compared to their as-sintered values by 139 %, 24 % and 123 %. The strength scatter decreased after ion exchange for the nepheline-containing glass-ceramics by 10 %. The characterised glass-ceramics in this work require further investigation and have the potential to be developed into layered glass powders, which can be ion exchanged after sinter-crystallization to produce dental restorations with superior mechanical and chemical properties.