Osteogenic Properties of Titanium Alloy Ti6Al4V-Hydroxyapatite Composites Fabricated by Selective Laser Melting

Hydroxyapatite (HA) has been widely used for coating metal bone implants. However, HA coating may separate from the metal substrates, resulting in poor performance such as inflammatory reactions which may finally lead to implant failure. Dispersing HA into metal substrate may be a viable solution but such a composite may suffer from inferior mechanical strength. Therefore, a functionally graded material (FGM) with HA dispersing in metal substrate in gradients is introduced to increase surface osteogenic capability and simultaneously maintain a good mechanical strength of the bone implant. In this study, Ti6Al4V(Ti64)-HA composite with different component of HA and their corresponding FGMs were fabricated by selective laser melting (SLM). It was demonstrated that compared with the pure Ti64 and Ti64-2.5%HA composite, Ti64-1%HA composite seemed to have a better osteogenic promoting property in vitro. Both the FGMs significantly promoted the osteogenic activities of the pure Ti64 in vivo. Moreover, functionally graded structure improved the anti-compression properties of composites.