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The integration of biological and mechanical requirements remains a challenge in developing porous hydroxyapatite (HA) and tri-calcium phosphate (TCP) scaffolds for load-bearing bone implant application. With the newly developed slipdeposition and coating-substrate co-sintering technique, a strong layered HA/TCP-zirconia scaffold composite structure was successfully fabricated. The bending strength (321 MPa) of this composite can match upper strength limit of the natural compact bone. The HA-based scaffold coating has multiple scale porous structures with pore size ranging 1-10 and 20-50 lm. The zirconia-based substrate is also porous with submicropores. Focus ion beam micrographs show most of the micropores in the coating are interconnected. Microindentation and primarily adhesive strength tests demonstrate that the scaffold coating strongly bonds with the zirconia based substrate. In vitro cell culture study indicates that the coatings have no cytotoxicity. It is evident that the strong layered HA-zirconia scaffold composite offers new implant options for bone repairs requiring immediate load bearing capacity.

This study presents a dipcasting method that can deposit both porous and dense bioceramic coatings onto 3D Ti-mesh made from commercially pure Ti-mesh for surgical applications. First, a dense bioglass coating was deposited onto the 3D Ti-mesh, which is to seal off the Ti-mesh. Second, a microporous HA/bioglass coating was deposited on top of the dense bioglass coating, which is to promote bone regeneration into the 3D Ti-mesh. X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy were used to analyze the bioceramic coatings and cross-sectional microstructures. Vickers microhardness across the interface between bioceramic coating and Ti-substrate was measured.

Bioceramic scaffolds with desired bone regeneration functions have the potential to become real alternatives to autologous bone grafts for reconstruction of load-bearing and critical-sized segmental bone defects. The aim of this paper was to develop a layered scaffold structure that has the biodegradable function of common monolithic scaffolds and adequate mechanical function for surgical fixing and after surgery support. The exemplary case of this study is assumed to be a large-segment tibia or femur bone repair. The layered scaffold structure consists of a macro porous hydroxyapatite-wollastonite layer and a strong dense zirconia matrix dense layer. The bio-functional scaffold layer with interconnected freeze-dried porous structures shows excellent apatite formation, cell attachment, and cell proliferation capabilities. The mechanical functional layer provides a bending strength matching that of the compact bone.

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