3D Printing in alloy design to improve biocompatibility in metallic implants.

ABSTRACT

3D Printing (3DP) or additive manufacturing (AM) enables parts with complex shapes, design flexibility, and customization opportunities for defect specific patient-matched implants. 3DP or AM also offers a design platform that can be used to innovate novel alloys for application-specific compositional modifications. In medical applications, the biological response from a host tissue depends on a biomaterial's structural and compositional properties in the physiological environment. Application of 3DP can pave the way towards manufacturing innovative metallic implants, combining structural variations at different length scales and tailored compositions designed for specific biological responses. This study shows how 3DP can be used to design metallic alloys for orthopedic and dental applications with improved biocompatibility using in vitro and in vivo studies. Titanium (Ti) and its alloys are used extensively in biomedical devices due to excellent fatigue and corrosion resistance and good strength to weight ratio. However, Ti alloys' in vivo biological response is poor due to its bioinert surface. Different coatings and surface modification techniques are currently being used to improve the biocompatibility of Ti implants. We focused our efforts on improving Ti's biocompatibility via a combination of tantalum (Ta) chemistry in Ti, the addition of designed micro-porosity, and nanoscale surface modification to enhance both in vitro cytocompatibility and early stage in vivo osseointegration, which was studied in rat and rabbit distal femur models.