Influence of the MgO-TiO2 Co-Additive Content on the Phase Formation, Microstructure and Fracture Toughness of MgO-TiO2-Reinforced Dental Porcelain Nanocomposites

Abstract

The influence of the co-additive concentration (0 -45 wt% with an interval of 5 wt%) of MgO-TiO 2 on the phase formation, microstructure and fracture toughness of MgO-TiO 2 -reinforced dental porcelain nanocomposites derived from a one-step sintering technique were examined using a combination of X-ray diffraction, scanning electron microscopy and Vickers indentation. It was found that MgO-TiO 2 -reinforced dental porcelain nanocomposites exhibited significantly higher fracture toughness values than those observed in single-additive (MgO or TiO 2)-reinforced dental porcelain composites at any given sintering temperature. The amount of MgO-TiO 2 as a co-additive was found to be one of the key factors controlling the phase formation, microstructure and fracture toughness of these nanocomposites. It is likely that 30 wt% of MgO-TiO 2 as a co-additive is the optimal amount for MgTi 2 O 5 and Mg 2 SiO 4 crystalline phase formation to obtain the maximum relative density (96.80%) and fracture toughness (2.60 ± 0.07 MPa•m 1 / 2) at a sintering temperature of 1000°C.