Mechanical properties of polymer-infiltrated-ceramic (sodium aluminum silicate) composites for dental restoration

Objective: To fabricate indirect restorative composites for CAD/CAM applications and evaluate the mechanical properties. Methods: Polymer-infiltrated-ceramic composites were prepared through infiltrating polymer into partially sintered sodium aluminum silicate ceramic blocks and curing. The corresponding samples were fabricated according to standard ISO-4049 using for mechanical properties measurement. The flexural strength and fracture toughness were measured using a mechanical property testing machine. The Vickers hardness and elastic modulus were calculated from the results of nano-indentation. The microstructures were investigated using secondary electron detector. The density of the porous ceramic blocks was obtained through TG-DTA. The conversion degrees were calculated from the results of mid-infrared spectroscopy. Results: The obtained polymer infiltrated composites have a maximum flexural strength value of 214 +/- 6.5 MPa, Vickers hardness of 1.76-2.30 GPa, elastic modulus of 22.63-27.31 GPa, fracture toughness of 1.76-2.35 MPa m(1/2) and brittleness index of 0.75-1.32 mu m(-1/2). These results were compared with those of commercial CAD/CAM blocks. Our results suggest that these materials with good mechanical properties are comparable to two commercial CAD/CAM blocks. Conclusion: The sintering temperature could dramatically influence the mechanical properties. Clinical significance: Restorative composites with superior mechanical properties were produced. These materials mimic the properties of natural dentin and could be a promising candidate for CAD/CAM applications.