Fracture behavior of lithia disilicate- and leucite-based ceramics

Objective: This study was designed to characterize the fracture behavior of ceramics and test the hypothesis that variation in strength is associated with a variation in fracture toughness. Methods: The following four groups of 20 bar specimens (25×4×1.2 mm) were fabricated (ISO standard 6872): E1, a hot-pressed leucite-based core ceramic (IPS Empress); E2, a hot-pressed lithia-based core ceramic (IPS Empress 2); ES, a hot-pressed lithia-based core ceramic (Experimental); and GV, a glass veneer (IPS Empress2 body). Specimens were subjected to four-point flexure loading in 37 °C distilled water. Fractographic analysis was performed to determine the fracture origin ( c) for calculation of fracture toughness ( K IC). Weibull analysis of flexure strength ( σ) data was also performed. Results: Differences in mean σ and K IC were statistically significant for E1 and GV ( p