Investigation of Spark Plasma Sintering on Microstructure-Properties of Zirconia Reinforced Fluormica Glass for Dental Restorations

Abstract

Background: Conventional sintering methods of dental ceramics have limitations of high temperature and slow cooling rates with requirements of additional heat treatment for crystallization. Spark plasma sintering (SPS) is an emerging technique that has the potential to process dental restorations with dense microstructures and tailor-made clinically relevant properties with optimized processing parameters. This study explored the potential of the SPS of zirconia-reinforced fluormica glass (FM) for dental restorative materials. Methods: FM glass frit was obtained through the melt-quench technique (44.5 SiO2–16.7 Al2O3–9.5 K2O–14.5 MgO–8.5 B2O3–6.3 F (wt.%)). The glass frit was ball-milled with 20 wt.% of 3 mol% yttria-stabilized zirconia (FMZ) for enhanced fracture toughness. The mixtures were SPS sintered at a pressure of 50 MPa and a heating rate of 100 °C/min for 5 min with an increase in temperature from 650–750 °C–850 °C–950 °C. Phase analysis was carried out using XRD and microstructural characterization with SEM. Micro-hardness, nano-indentation, porosity, density, indentation fracture toughness, and genotoxicity were assessed. Conclusions: The increase in the SPS temperature of FMZ influenced its microstructure and resulted in reduced porosity, improved density, and optimal mechanical properties with the absence of genotoxicity on human gingival fibroblast cells.