Preparation And Characterization Of Bicontinuous 3Y-TZP/PMMA Composites

At present,the problem of tooth restoration has attracted extensive attention.Zirconia all-ceramic crown prosthesis has been widely used in clinical practice due to its good appearance and biocompatibility.But the extra high hardness of zirconia will cause excessive wear of natural tooth.PMMA-a kind of organic resin polymerized by MMA,has both good biocompatibility and good toughness.However its strength and hardness are relatively low.Therefore,considering the advantages of resins and ceramics,a 3Y-TZP/PMMA bicontinuous composites with high bending strength,fracture toughness and hardness for tooth restoration was prepared in this paper.Using 3Y-TZP powders as raw material,series of 3Y-TZP porous ceramics skeletons have been prepared using foam-gelcasting method by adjusting the solid content and concentration of foaming agent.The results showed that the solid content and concentration of foaming agent had a significant impact on the porosity,pore structure and mechanical properties of the skeleton,and the skeleton with the 50.13%total porosity and 46.06%apparent porosity exhibited the highest mechanical properties(the bending strength and fracture toughness of the skeleton were 77.28 MPa and 2.16 MPa m1/2 respectively)when the solid content was 25 vol.%and concentration of foaming agent was 0.1 g/L.The prepared porous ceramic skeleton was pretreated with silanization,and then series of 3Y-TZP/PMMA bicontinuous composites were fabricated by infiltrating the MMA containing initiator into the porous ceramics and polymerized in situ.The mechanical properties of the composites prepared from the above skeleton were the highest(bending strength and fracture toughness were 152 MPa and 3.59 MPa·m1/2 respectively).The prepared composites from solid content of 25 vol.%and foming agent concentration of 0.5 g/L had good two-phase dispersion,and its bending strength and fracture toughness reached 106 MPa and 2.47 MPa·m1/2 respectively.The infiltration process has a significant effect on the structure and properties of the bicontinuous composites.The combination of ultrasonic vibration method during the silanization porcess and vacuum method during the MMA infiltration process(ultrasound+vacuum process)was benefit to achieve a good infiltration effect.Porous 3Y-TZP ceramics with total porosity of 74.72%and apparent porosity of 72.89%was used as skelton,which were prepared by foam-gelcasting method from solid content of 25 vol.%and foaming agent concentration of 0.5 g/L sintered at 1400?.And the 3Y-TZP/PMMA bicontinuous composites were fabricated by ultrasound+vacuum process.The bending strength,fracture toughness and vickers hardness of the composites prepared by the above process were 118 MPa,2.65 MPa ml/2 and 0.58 GPa.Properties of the composites can meet requirements of the national standard(GB 30367-2013)for denture restoration material of aesthetic ceramic and base ceramic of a single unit of front or back teeth restoration through adhesive retention.