Effect of porosity and curing pressure on flexural strength of resin infused feldspathic porcelains

Abstract

Objectives: The objectives of this study were to: Investigate the effect of sintering temperature on the microstructure and density of two different ceramics. Investigate the effect of curing pressure on flexural strength of resin infused ceramic and resin-infused porcelain fabricated at various sintering temperatures. Compare flexural strength of study materials to commercial CAD/CAM monolithic materials. Materials: RIC and clear MKII ceramic powders were the experimental materials used in this study. Vitablock MKII, Vita Enamic and LAVA Ultimate were used as controls. Methods: Ceramic powders were dry-pressed in cylindrical molds and then sintered at various temperatures. The sintered density of each block specimen was measured then the block was treated with a silane coupling agent before infusion with UDMA/TEGDMA resin under vacuum. Resin infused ceramic blocks were cured under pressure and sectioned into bars. Flexural strength was measured with a 3 point bending test. The microstructure of each group was investigated using scanning electron microscope (SEM). Statistics: Data were analyzed with ANOVA and compared with a Tukey post-hoc test. Results and Conclusions: The clear MKII ceramic required lower firing temperature to achieve the same density as RIC. The ceramic density had a significant effect on the flexural strength of resin infused ceramic. Interpenetrating phase materials had greater flexural strength than single phase feldspathic porcelain. Under the test conditions, the curing pressure had no significant effect on the flexural strength of resin infused ceramic blocks.