The effects of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser and silicon carbide (SiC) paper on the surface micro-topography of titanium-6 aluminium-4 vanadium (Ti6Al4V) alloy were examined in relation to the response of bone cells. The study was performed in three distinct stages: (1) after surface treatment of samples by laser and SiC paper, the surface hardness, surface roughness, corrosion resistance and surface tension were evaluated; (2) the growth of mouse connective tissue fibroblast cells (L-929) on untreated and treated samples was assessed in vitro; (3) the response of goat osteoblast cells to untreated and treated implanted samples was assessed in vivo. The surface roughness varied between 7 +/- 0.02 for laser-treated samples (LTSs) at 140 J cm(-2) and 21.8 +/- 0.05 for mechanically treated samples (MTSs). The surface hardness was found to vary from 377 Vickers hardness number (VHN) for MTSs to 850 VHN for LTSs. A corrosion potential of -0.21V was achieved for the LTSs compared with -0.51V for the MTSs. The LTSs exhibited a more hydrophilic behaviour (i.e. wettability) than did the MTSs. No cytotoxicity effect, unlike for the MTSs, was observed for the LTSs. The results of in vivo tests indicated longitudinal growth of osteoblast cells along the grooves on the samples formed by the SiC paper, and multidirectional spreading of the cells on the LTSs.

The effect of Nd:YAG laser surface modification on the microtopography and physicochemical properties of Ti-6Al-4V alloy has been investigated with a view of biomedical applications. The surface roughness and hardness of laser treated samples at 140 J cm 22 were found to be 7¡0?02 and 825 VHN respectively. The superior microhardness value can be attributed to grain refinement associated with laser melting and rapid solidification. The electrochemical property, mainly pitting corrosion resistance, has been carried out in Hank's salt balanced physiological solution using standard potentiodynamic polarisation testing. A higher corrosion potential of 20?21 V was achieved for laser treated samples. At the optimum of laser fluence (140 J cm 22 ), energy dispersive X-ray analysis showed about a 30% decrease in vanadium content. Contact angle measurements also indicated improved surface wettability (i.e. hydrophilicity) characteristics at 35u. Finally, cell culture studies provided a useful tool to investigate the morphology and cell cytotoxicity of the laser treated surfaces.