MgO, SiO2, Al2O3, MgF2, CaF2, CaCO3, SrCO3, and P2O5 were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892°C (second crystallization temperature+20°C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa√m) combined with the hardness to give a lower brittleness index (1.81 µm −1/2 ) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium micafluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM.

Four formulas of the stoneware bodies were formulated with and without an increasing amount of lithium oxide. The bodies were designed to vitrify at the temperature lower than 1150°C. A comparison on the physical properties and the phase formation of the bodies after firing at the temperature of 1100°C, 1150°C, and 1200°C was studied. The experiment results showed that the bodies containing lithium oxide vitrified at lower temperature and showed less variation in water absorption, density, and shrinkage values in the firing range 1100-1200°C. The XRD results showed that, at 1100°C, all the bodies composed of mullite, albite, and quartz. A reduction in the <em>amount</em> of albite and quartz associated with mullite formation was observed when increasing the amount of lithium oxide or the temperature. Furthermore, the body with lithium oxide tended to have higher value of the Modulus of Rupture.