Effect of Crystallinity on Strength and Fracture Toughness of Li2O-Al2O3-CaO-SiO2 Glass-Ceramics

The influence of crystal volume fraction on fracture toughness ( K _{I C} ) and indentation strength was analyzed for Li₂O-Al₂O₃-CaO-SiO₂ (LACS) and LACS glass-ceramics containing 0.58 mmol% AgNO₃ (LACS-0.58Ag) or 0.78 mmol% AgNO₃ (LACS-0.78Ag). The mean flexure strength, indentation strength, and K_{I C} values of the LACS-0.78Ag groups increased with volume fraction of crystallinity. To achieve the greatest strength and K_{I C} in LACS-Ag specimens, a high volume fraction of crystallinity (95%) had to be produced. However, the relationship between volume fraction of crystal phase and translucency had to be analyzed to determine the influence of crystallization on the potential esthetic results that are essential for dental applications. Addition of AgNO₃ to LACS glass produced a change from surface crystallization to bulk crystallization.