Effects of pore connectivity and microstructure on mechanical performance of ZrO2 scaffolds and PMMA-infiltrated ZrO2 composites

To combine the advantages of ceramics and resins, ceramic/resin composites have been explored for dental restorations in recent years. ZrO2 scaffold is considered as a promising candidate porous matrix for polymer-infiltrated composites due to its excellent biocompatibility and mechanical properties. In the present study, porous ZrO2 scaffolds were prepared by adding pore-forming agent and sintered at 1200-1400 °C, the effects of porosity, pore connectivity and microstructure on the mechanical performance of ZrO2 scaffolds and the corresponding PMMA-infiltrated ZrO2 composites were investigated. To obtain a good pore connectivity and favorite mechanical properties of ceramic scaffolds, the content of pore-forming agent and sintering temperature should be well controlled. The flexural strength of ZrO2 scaffolds was simply affected by the total porosity and sintering temperature. While the flexural strength of the infiltrated composites was dominated by both the strength of the porous scaffolds and the amount of closed pores. Crack bridging in the infiltrated composites is one of the important factors to the enhanced mechanical strength. The highest strength of 265.5 MPa was achieved in the composites infiltrated from the 1400°C-sintered scaffolds with an initial pore forming agent content of 30 wt%.