Technological watch

Titanium (Ti)-based alloys exhibit low elastic modulus that better match the modulus of human bones than several other metallic biomaterials while providing high strength to weight ratio and corrosion resistance. The rapid emergence of additive manufacturing (AM) and three-dimensional (3D) printing offers the advantage of producing complex geometries with the potential benefit of engineering patient-specific devices for various biomedical implants, which are otherwise difficult to achieve through conventional processes. Typically, the performance of as-built Ti-alloy implants fabricated by AM are limited owing to the low surface quality, surface imperfections, and defects introduced by layer-by-layer deposition processes. Research in recent years demonstrates that post-fabrication surface engineering techniques offer promise for enhancing the performances of additively manufactured components. This review systematically describes the recent advances in surface engineering of Ti- alloys fabricated by AM toward clinical use of these implants. Popular surface treatments by the action of chemicals, heat, and laser are described. Coatings are also widely explored, and recent developments in preparing coatings of hydroxyapatite, oxide, calcium carbonate, and bioactive glasses are discussed. The effects of the surface treatment on the physicochemical properties and the biological response are described. The challenges and opportunities for attaining greater control over the surface properties of additively manufactured Ti-based biomaterials by post-AM surface treatments for enhancing the clinical performance of implants are highlighted.