Biocompatibility of Advanced Manufactured Titanium Implants—A Review

Abstract

Titanium (Ti) and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing) or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible that advanced manufacturing techniques could replace the machining or casting of metal alloys in the manufacture of devices because of associated advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants. The emerging advanced manufacturing approaches of metal injection moulding and additive layer manufacturing are receiving particular attention from the implant fabrication industry because they could overcome some of the difficulties associated with traditional implant fabrication techniques such as titanium casting. Using advanced manufacturing, it is also possible to produce more complex porous structures with improved mechanical performance, potentially matching the modulus of elasticity of local bone. While the economic and engineering potential of advanced manufacturing for the manufacture of musculo-skeletal implants is therefore clear, the impact on the biocompatibility of the materials has been less investigated. In this review, the capabilities of advanced powder manufacturing routes in producing components that are suitable for biomedical implant applications are assessed with emphasis placed on surface finishes and porous structures. Given that biocompatibility and host bone response are critical determinants of clinical performance, published studies of in vitro and in vivo research have been considered carefully. The review concludes with a future outlook on advanced Ti production for biomedical implants using powder metallurgy.

Porous Titanium for Dental Implant Applications

“…Additive manufacturing technology has more specifically been applied to produce non-porous parts with complex geometry for use in implants, such as dental, craniofacial, maxillofacial and orthopedic implants [59]. In 2002, Tolochko et al demonstrated the possibility of producing dental root implants from Ti powders with two different zones, comprising a compact core and irregular porous shell by incorporating (SLS) for the porous surface and (SLM) for the solid core.…”

“…Titanium is well known as a relatively high cost engineering material due to the difficulties in the extraction, forming and machining processes [59]. Traditionally, a titanium alloy dental root implant is manufactured via a casting or powder metallurgy route [60].…”

Welding and Joining of NiTi Shape Memory Alloys: A Review

“…The most used Titanium alloys is the biphasic α + β Ti6Al4V [273]. In the biomedical industry, they are highly considered due to its high specific strength and excellent biocompatibility [274], where can substitute hard tissues [275]. In aerospace structures and propulsion systems, this alloys is commonly used due to the exceptional combination of mechanical and corrosion properties, associated with low weight [276].…”

Mechanical Properties and In Vitro Behavior of Additively Manufactured and Functionally Graded Ti6Al4V Porous Scaffolds

“…These shortcomings can be overcome through additive manufacturing which builds a three-dimensional object in layer-by-layer fashion. Selective laser melting (SLM) and electron beam melting (EBM) have both been utilized to successfully fabricate porous scaffolds [36]. Both methods rely on a computer-controlled high power energy source to selectively melt a metallic powder on each layer.…”