Effect of Glass Compositions on Crystallization and Mechanical Properties of Lithium Disilicate Glass Ceramics for Dental Crown

Abstract:

This work proposes three different glass formula derived from the SiO₂-Li₂O-K₂O-Al₂O₃ system to investigate the effect of glass compositions on their crystal formation and mechanical properties. Glass LD_1 was SiO₂-Li₂O-K₂O-Al₂O₃ system with adding P₂O₅ and CaF₂ as nucleating agents. In Glass LD_2, a few amount of MgO was mixed to improve the viscosity of the glass. Finally, an important factor of Si:Li ratio was increased in Glass LD_3. Glass batches were melted at 1500°C and cast into a graphite mold which was annealed at 400-500°C before heat treatment at 700, 750, 800 and 850°C. XRD results can be indexed Li₂Si₂O₅, Li₂SiO₃, Ca₅(PO₄)₃F and SiO₂ as an early crystallization when heat treated at 700°C. After heat treatment at 750-850°C, the intensity of SiO₂ disappeared and the peaks associated to Li₃PO₄ appeared; meanwhile, Li₂Si₂O₅ increased in intensity. Adding MgO resulted in decreasing the viscosity of the glass with no significant effects on the formation of lithium disilicate. By increasing Si:Li ratio, the peak of SiO₂ more obviously observed. SEM results revealed the development of microstructure from plate-like to interlocking rod-shaped crystals in all glasses. The highest indentation fracture toughness and biaxial flexural strength found in all glass ceramics heat treatment at 800°C because the finest microstructure observed at this temperature, except LD_3 heat treated at 850°C, which obtained the finest microstructure. LD_1 heat treated at 850°C presented the best chemical solubility 59 μg/cm².

• Periodical: Advanced Materials Research (Volume 747)
• Pages: 194-197
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.747.194
• Online since: August 2013
• Authors: Naruporn Monmaturapoj, Pornchanok Lawita, Witoon Thepsuwan
• Keywords: Crystallization, Dental Crown, Glass Ceramics, Lithium Disilicate

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