Effect of titanium carbide coating on the osseointegration response in vitro and in vivo

Titanium has limitations in its clinical performance in dental and orthopaedic applications. This study describes a coating process using pulsed laser deposition (PLD) technology to produce surfaces of titanium carbide (TiC) on titanium substrates and evaluates the biological response both in vitro and in vivo. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of 18.6-21.5% TiC in the surface layer, accompanied by oxides of titanium 78.5-81.4% in the following concentrations: 11.1-13.0% Ti(2)O(3), 50.8-55.8% TiO(2), 14.5-14.7% TiO. Expression of genes central to osteoblast differentiation (alkaline phosphatase, A2 pro-collagen type 1, osteocalcin, BMP-4, TGFbeta and Cbfa-1) were up-regulated in all cell lines (primary human osteoblasts, hFOB1.19 and ROS.MER#14) grown on TiC compared with uncoated titanium when measured by semiquantitative PCR and real time-PCR, whilst genes involved in modulation of osteoclastogenesis and osteoclast activity (IL-6 and M-CSF) were unchanged. Bone density was shown to be greater around TiC-coated implants after 2 and 4 weeks in sheep and both 4 and 8 weeks in rabbits compared to uncoated titanium. Rapid bone deposition was demonstrated after only 2 weeks in the rabbit model when visualized with intravital staining. It is concluded that coating with TiC will, in comparison to uncoated titanium, improve implant hardness, biocompatibility through surface stability and osseointegration through improved bone growth.