Resin composite blocks via high-pressure high-temperature polymerization

Objectives m of this study was to thermo-polymerize under high pressure four commercially available dental resin composites to obtain and characterize composite blocks suitable for CAD/CAM procedures. s (GC, Japan), Vita VM LC (Vita Zahnfabrik, Germany), Grandio (VOCO, Germany), and EsthetX (Dentsply, Germany), were selected for this study. Paradigm (3 M ESPE, USA), a CAD/CAM composite block, was included for comparison. Composite blocks were obtained through polymerization at high-temperature high-pressure (HT/HP). Samples for mechanical/physical characterizations were cut from Paradigm and HT/HP composite blocks while control samples were obtained by photo-polymerizing (PP) the materials in molds. Flexural strength (σf), fracture toughness (KIC), hardness, and density (ρ) were determined and compared by pairwise t-tests (α = 0.05). Fractured surfaces were characterized under a scanning electron microscope. s sults have shown that HT/HP polymerization resulted in a significant (p < 0.05) increase in σf, hardness, and ρ for all composites investigated. Even if KIC of all materials was increased by HT/HP polymerization, significant increases were detected only for Gradia and EsthetX. The Weibull modulus of HT/HP polymerized composites was higher than that of PP counterparts. HT/HP materials had higher σf, Weibull modulus, and KIC compared to Paradigm. The most significant SEM observation of fractured KIC specimens from all the materials tested was the presence of fewer and smaller voids in HT/HP polymerized composites. icance sults of this study suggest that HT/HP polymerization could be used to obtain dental resin composite blocks with superior mechanical properties, suitable for CAD/CAM processing.