Titanium Alloy Lattices with Regular and Graded Porosity for Dental Implant Applications

Interconnected porous titanium components prepared by additive manufacturing technologies have a great potential in dental and orthopaedic implants, due to their biocompatibility, lower stiffness and larger surface area compared to dense structures. Therefore they should permit better bone-implant integration. Graded porosity may provide large pores for bone ingrowth on the periphery of an implant and a denser core to sustain mechanical loading. However, the optimal porosity and structure for the mechanical and biological performance of load-bearing implants remains undefined. Given the small size of dental implants it is very challenging to achieve gradations in porosity. Therefore, this thesis aimed to develop a range of lattices from the titanium alloy Ti-6Al-4V of regular and graded porosity via selective laser melting. The effects of pore variance on mechanical and biological properties were investigated. These lattices were designed to be rod-shaped with dimensions representing the size of current dental implants. Surface chemistry and mechanical properties of these components were investigated. The potential to support bone in-growth was evaluated by direct seeding of bone cells on the lattices and cell viability, and extracellular matrix deposition was evaluated. To evaluate cell migration, an in vitro 3D culture model was invented; the porous Ti-6Al-4V lattices were implanted into a ring of porous polymer sponge that had been pre seeded with boneforming cells. Our results confirmed that Ti-6Al-4V lattices were duplicated from the CAD models and characterised by interconnected porosity. Mechanical tests revealed good strength properties comparable to bone tissue, but a dense core was required to maintain
strength in the high porosity structures. All samples were a suitable for growing osteoblast cells and supporting bone formation with good mineral deposition. It was demonstrated that a tissue engineering approach could be used to examine optimum cell migration and
extracellular bone matrix deposition on the implanted titanium in vitro and bone formation within the pores of the implanted titanium after explantation was confirmed.