Stereolithography-Based Additive Manufacturing of High-Performance Osteoinductive Calcium Phosphate Ceramics by a Digital Light-Processing System

Digital light processing (DLP) is one of the additive manufacturing (AM) technologies suitable for preparation of high-performance ceramics. The present study provided an optimized formula to fabricate osteoinductive calcium phosphate (CaP) ceramics with high precision and controllable three-dimensional (3D) structure. Among the four surfactants, monoalcohol ethoxylate phosphate was the best one to modify the CaP powders for preparing the photocurable slurry with high solid loading and good spreading ability. By testing the photopolymerization property of the 60 wt % solid loading slurry, the appropriate processing parameters including the slice thickness (50 μm), exposure intensity (10.14 mW/cm2), and exposure time (8 s) were set to perform the 3D printing of the ceramic green body in the DLP system. After the debinding and sintering, the final CaP ceramics were acquired. The stereomicroscope and SEM observation confirmed the high precision of the ceramics. The average compressive strength of the ceramics with 64.5% porosity reached 9.03 MPa. On only soaking in simulated body fluid for 1 day, an even layer of apatite formed on the ceramic surface. The cell culture confirmed that the ceramics could allow the good attachment, growth, and proliferation of murine bone marrow mesenchymal stem cells. After implantation into the dorsal muscles of beagle dogs for 3 months, abundant blood vessels and obvious ectopic bone formation were observed clearly by the histological evaluation. Therefore, with good bioactivity and osteoinductivity as well as high precision and adjustable mechanical strength, the 3D printed CaP ceramics in the DLP system could have good potential in customized bone-repairing applications.