The micro-flow extrusion forming of ceramic material has not been developed in three dimensional (3D) printing field. The shape forming of material is by bonding and stacking of filaments of ceramic slurry extruded through micro-sized pores with rather large gaps and porosities, which can affect material’s density after sintering and its mechanical property thereafter. Aiming at such a deficiency of this process, the preparation method of ceramic denture printing paste applicable to the process is studied, and the properties of slurry and sintering performance are analyzed and tested. It is concluded that the rheological properties of the prepared ceramic slurry conforms the requirement of micro-flow extrusion process, and the green body after sintering can satisfy the mechanical property requirement of oral denture. This is a technologic breakthrough, laying a foundation for the application of micro-flow extrusion forming in 3D printing of ceramic material, and promoting its development and maturation.
Tricalcium phosphate (TCP) is one of the most widely used bioceramics for constructing bone tissue engineering scaffold. The three-dimensional (3D) printed TCP scaffold has precise and controllable pore structure, while with the limitation of insufficient mechanical properties. In this study, we investigated the effect of sintering temperature on the mechanical properties of 3D-printed TCP scaffolds in detail, due to the important role of the sintering process on the mechanical properties of bioceramic scaffolds. The morphology, mass and volume shrinkage, porosity, mechanical properties and degradation property of the scaffold was studied. The results showed that the scaffold sintered at 1 150℃ had the maximum volume shrinkage, the minimum porosity and optimal mechanical strength, with the compressive strength of (6.52 ± 0.84) MPa and the compressive modulus of (100.08 ± 18.6) MPa, which could meet the requirements of human cancellous bone. In addition, the 1 150℃ sintered scaffold degraded most slowly in the acidic environment compared to the scaffolds sintered at the other temperatures, demonstrating its optimal mechanical stability over long-term implantation. The scaffold can support bone mesenchymal stem cells (BMSCs) adherence and rapid proliferation and has good biocompatibility. In summary, this paper optimizes the sintering process of 3D printed TCP scaffold and improves its mechanical properties, which lays a foundation for its application as a load-bearing bone.