Fabrication of a high-strength lithium disilicate glass-ceramic in a complex glass system

The aim of this work was to develop a high-strength lithium disilicate glass-ceramic for dental restorative applications. A complex lithium disilicate glass composition was designed in the SiO2-Li2O-CaO-P2O5-ZrO2 glass system. Three sets of samples were employed to investigate the effects of heating profile, crystallization annealing temperature and holding time on the phase evolution, microstructure and mechanical properties. The results show that no lithium metasilicate was detected during the crystallization process. Semi-quantitative analysis reveals that the lithium disilicate glassceramics consist of 57-62 wt% of rod-like lithium disilicate crystallites. A high flexural strength of 439 +/- 93 MPa was observed in the glass-ceramic when it was subjected to two-stage annealing at 674 degrees C. Additional higher temperature annealing stages were of little help for the improvement of bending strength, but did enhance the Vickers indentation fracture toughness (VIF) from 0.93 to 1.29 MPa center dot m(1/2). It is found that both the crystallization temperature and the holding time affect the phase transformation, morphology, and crystallite size of these glass-ceramics, but the crystallization temperature has a more profound effect than the holding time. The glass-ceramic developed in this study could be a good candidate for dental restorative applications, especially for posterior three-unit bridges. (C) 2013 The Ceramic Society of Japan and the Korean Ceramic Society. Production and hosting by Elsevier B.V. All rights reserved.