Preparation and Characterization of Dental Ceramic, Effect of Al2O3 and Hydroxyapatite on Mechanical Properties

Dental ceramic has been widely used in restorative dentistry, as it is beautiful and like natural teeth. This work studied the preparation of dental ceramic and the effect of added Al2O3 and hydroxyapatite (HA) on mechanical properties. The dental ceramic was prepared by mixing the starting metal oxide materials and melting at 1550 degrees C for 4 h. Then the molten glass was quenched rapidly into water at room temperature and ground to obtain glass frit powder. To the powder was added Al2O3 and HA at various ratios and pressed into a mold 10 mm in diameter. Finally, the samples were sintered at 960 degrees C in a vacuum electrical furnace. The crystal structure and microstructure were observed by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The hardness was investigated by Vickers hardness (HV) and Knoop hardness (HK) testing. The modulus of elasticity (E) and fracture toughness (K-IC) were calculated. The biocompatibility was observed by a MTT test on Vero cells. Results indicated that the dental ceramics had two phases as an amorphous phase of glass and a crystal phase of leucite. HV and HK of dental ceramics were in the range of 4.14-4.35 GPa and 3.07-3.62 GPa respectively. K-IC increased with the Al2O3 and HA. The viability of the dental ceramics was 94.0 +/- 0.4-100.0 +/- 0.0%.