Interfacial characteristics of bioglass diffusion zone between scaffold-like hydroxyapatite/wollastonite coating and dense zirconia substrate

Abstract

A thin bioglass (BG) layer or diffusion zone has been used to enhance interfacial bonding between co-sintered scaffold-like micro-porous hydroxyapatite (HA) coating over dense zirconia substrate. However, there still have problems such as low fracture toughness and low wear resistance. Therefore, while meeting the basic requirements of degradability and biocompatibility, how to improve the mechanical properties of the scaffold, endow it with osteoinductivity and build a low-density porous structure has become the focus of bone scaffold research. The tri-layer bio-ceramic composites, consisting of porous HA, BG diffusion zone, and strong zirconia substrate, are designed with superior loading-bearing capability to the scaffold. Surface handling properties of the scaffold-like HA coating are further enhanced by incorporating wollastonite. The gradient in material compositions across the coating and substrate interface is further minimized by adding HA into the zirconia substrate. Benefiting from these special design and the thin BG diffusion zone, the tri-layer bio-ceramics present excellent interfacial strength, which ensures good structural strength and machinability. The results could provide the feasible options for bio-ceramic scaffolds design and manufacturing process, thus advance the practical clinical applications of HA-based scaffolds for bone repair and regeneration.