Advanced Dynamic Slurry Circulation System for Precision 3D Bioprinting of Osteogenic Ceramics: Enhanced Stability, Mechanical Performance Optimization, and In Vitro Bioactivity Validation.

This study presents an improved 3D printing technology that integrates a slurry circulation system (SCS) to optimize the quality of low-viscosity ceramic slurries and address the issue of slurry sedimentation during printing. The use of low-solid-content slurries, traditionally challenging due to sintering shrinkage, is a key feature of this work. The resin solvent completely burns off during sintering, while the remaining solid portion undergoes controlled shrinkage, enabling the production of high-precision ceramics with reduced demands on 3D printer accuracy. Although often avoided in ceramics, this shrinkage can help improve structural accuracy and reduce manufacturing costs. The efficacy of the SCS was validated through fluid dynamics simulations and sedimentation experiments using COMSOL Multiphysics software. The modified technology was used to fabricate bioceramics with various triply periodic minimal surface (TPMS) structures, which were characterized for porosity, pore size, and mechanical properties. In vitro cell experiments demonstrated that the fabricated ceramics had no adverse effects on the survival, proliferation, migration, or osteogenic differentiation of MC3T3-E1 cells, indicating good biocompatibility and osteogenic potential. The SCS significantly reduced slurry sedimentation, improved printing precision, and increased the yield of high-quality ceramics to 97.73%. The resulting bioceramics exhibited high porosity (∼70%) and small pore sizes (∼50 μm), with excellent mechanical properties (compressive strength of 4.00 ± 0.42 MPa and Young's modulus of 453.00 ± 7.43 MPa for the Gyroid structure). These findings suggest that low-solid-content slurries offer a cost-effective and high-precision solution for 3D-printed bioceramics with promising applications in bone tissue engineering.