Influence of ZrO2 on the crystallization and properties of lithium disilicate glass-ceramics derived from a multi-component system

Lithium disilicate glass-ceramic in the Li2O–SiO2–Al2O3–K2O–P2O5 system has been investigated by incorporation of ZrO2. The influence of ZrO2 on phase formation, microstructure, biaxial flexural strength and translucency were determined. Investigations were carried out by means of differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy. The mechanical strength was measured corresponding to dental norm ISO 6872 and the contrast ratio determined by BS 5612 method. Zirconia influences the crystallization by hampering crystal growth. With the increasing ZrO2 content, the crystals become smaller. By increasing the crystallization temperature the crystal growth could be improved. The translucency of the glass-ceramic is adjusted by adding ZrO2. A highly translucent glass-ceramic with a contrast ratio of approx. 0.4 with a high strength microstructure has been developed.