High-performance integrated manufacturing of a 3Y-TZP ceramic crown through viscoelastic paste-based vat photopolymerization with a conformal contactless support

摘要

Ceramic vat photopolymerization has been one of the promising three-dimensional printing technologies for personalized zirconia crown with high dimensional accuracy and surface topography. However, insufficient material stability and complex procedure about auxiliary supports limit the application based on low viscosity slurry. In this work, we developed a photocurable ceramic paste, in which the high static viscosity and high yield stress characteristics allowed it to exhibit sufficient anti-settling and self-supporting capabilities. The rheological characteristics of the as prepared paste were measured by stress-controlled rheometer, and conformal contactless support was designed including top conformal structure without contact with the crown and appropriate empty layer. The 3D precision of crown was evaluated by laser scanning confocal microscope and optical surface scanner. In addition, mechanical properties and biocompatibility of sintered samples were systematically evaluated. The results demonstrated that the yield stress of the ceramic paste approached around 600 Pa, and integrate morphology at the bottom of the crown with the contactless supported zone was observed. 3D deviation between the printed crown scan data and the reference model was reduced within the range of 40-70 μm. Finally, the flexural strength and fracture toughness of the sintered zirconia ceramics reached 1117 MPa and 7.76 MPa·m~(1/2), respectively, as well as good biocompatibility by the lack of cytotoxicity and hemolytic reaction. The results indicate an important practical significance for the development of vat photopolymerization printing technology of viscoelastic paste and conformal contactless support strategy to realize the integrated manufacturing of ceramic crowns.