Advances in titanium bio-implants: Alloy design, surface engineering and manufacturing processes

Metallic biomaterials have been widely used as load-bearing prostheses, internal fixation devices, vascular/nonvascular stents and dental brackets, wires and implants because of their excellent mechanical strength and resilience. Metallic biomaterials are advancing rapidly with the innovative design and development of titanium (Ti)-based biomaterials due to their superior mechanical behavior, chemical properties, and biocompatibility. Even though Ti and its alloys are generally trusted for biomedical applications, there is still room for improvement because of the mechanical mismatch between bone and implant and the need for higher bioactivity. In recent years, much attention has been given to the design of new Ti alloys with improved properties tailoring processes such as heat treatment and severe plastic deformation, surface functionalization for fabricating implants with lower elastic moduli in combination with higher strength and better biocompatibility. Porous Ti has also attracted increasing interest because the 3D porous network can provide a favorable environment for bone in-growth and possess bone-like mechanical properties. Thus far, considerable efforts have been made to develop new manufacturing techniques for producing porous Ti, such as powder metallurgy and the additive manufacturing techniques.