A systematic study of high-performance hydroxyapatite processed by vat photopolymerization additive manufacturing

Vat photopolymerization (VPP) enables the fabrication of hydroxyapatite (HAp) with high resolution, complex geometry and interconnected porous structures. However, the inherent property characterization of the VPP-printed HAp as a comparative benchmark for peer studies is still lacking. This study systematically analyzed the performance of VPP-printed HAp with a 55 vol% solid loading, focusing on printability, fabrication quality, mechanical performance limits, reliability, and biological response. The optimized HAp slurry presented high polymerization reactivity and efficient, precise photocuring performance at 17 mJ/cm². With a high density of 98.98 % and compacted grain boundaries, the bending strength of the HAp reached 127 MPa, surpassing the highest reported value for 3D-printing HAp by 23.3 %. In vitro studies demonstrated that the VPP-printed HAp promoted osteoblast proliferation and osteogenic differentiation. The HAp fabricated via VPP with efficient printability, controllable fabrication accuracy (within 1 %) and quality, good mechanical performance and osteogenic activity showcased its promising potential in implant fabrication for bone tissue repair.