Additive manufacturing of magnesium-doped calcium silicate/zirconia ceramic scaffolds with projection-based 3D printing: Sintering, mechanical and biological behavior

The lack of traditional bioactivity in zirconia (ZrO2) and limitations in the personalization capabilities of conventional manufacturing processes pose significant challenges for alveolar bone defect repair. This study aims to investigate whether ZrO2/CSi-Mgx scaffolds, produced by combining magnesium-doped calcium silicate (CSi-Mg) as a doping phase with ZrO2 as the matrix, using projection-based 3D printing (3DPP) technology, exhibit favorable biocompatibility and mechanical properties at low sintering temperatures. The effect of CSi-Mg content (x%), pore structure and heating temperature on the strength of scaffolds were investigated systematically. Incorporation of CSi-Mg could readily adjust the sintering properties of the ZrO2 scaffolds and the scaffolds with low (10-20 %) CSi-Mg possess much higher strength (74-92 MPa) after 1150 degrees C. Meanwhile, the ZrO2/CSi-Mg10 scaffolds with Triply periodic minimum surfaces (TPMS) pore structure had a compression strength of over 92 MPa and maintained a respectable strength (63 MPa) even after immersion in Tris buffer for 6 weeks. Concurrently, cellular experiments showed that incorporation of CSi-Mg could enhance cellular adhesion, proliferation, and migration of the ZrO2 scaffolds and also promote the osteogenic property of the scaffolds. In conclusion, the ZrO2/CSi-Mg10 scaffold with TPMS pore structure showcases remarkable mechanical performance and bioactivity, holding the potential to facilitate in-situ bone regeneration within the alveolar bone.