Syntheses and characterization of Twofold Nepheline-Combeite Glass-Ceramics for Dental Application

Synthesis of glass-ceramics with a combination of specific crystalline phases can lead in materials with superior chemical, physical and mechanical properties. The aim of this study is to outline the potential of synthesizing a novel glass system which crystallise into two crystalline phase's nepheline-combeite and provide an end monolithic glass-ceramics via sinter crystallization route for dental applications. Four novel glass compositions based on the Na2O-CaO-Al2O3-SiO2 system were synthesized using the melt-quench method. Glasses were designed to contain 6 mole % of CaO and a total of 35 mole % of Al2O3 and Na2O. Experimental glasses were ground into fine powders and then sinter crystallized to monolithic glass-ceramics. The developed glasses and glass-ceramics were characterized using DSC, Dilatometry, X-ray diffraction, Nuclear Magnetic Resonance (MAS-NMR) and scanning electron microscopy. This study shows how the nepheline phase can be produced in combination with other secondary crystalline phases which allow tailoring of the chemical, physical and thermal properties of both the starting glasses and the end glass-ceramics, including their thermal expansions coefficients, glass transition temperatures, softening points, sintering and melting temperatures.