1996 Volume 60 Issue 9 Pages 897-901
The effects of surface treatments of Ti and Al on the relative growth ratio of L929 and the colony formation ratio of V79 cells were investigated. Ti and Al were oxidized inside the heating oven at 453 K(180°C) for 7.2 ks. These powders were suspended in the medium and were extracted for 173 ks(48 h) in the incubator with 95% air-5% CO2 atmosphere. The medium not containing any metallic powder (control) was also extracted under similar conditions. After filtering with a 0.2 μm filter, 1.5×104 L929 cells/ml and 102 V79 cells/ml were seeded in control and in the filtrates of the medium containing metallic powder. It was observed that, upon oxidation, the relative growth ratio of L929 cells for oxidized Al powder became almost equal to 0.8 after 346 ks(4 d) of incubation. This shows that a relatively strong oxide film is formed over the surface of Al powder, thus preventing Al ions to be released in the medium and, hence the relative growth ratio of L929 cells markedly increases. Anodic polarization measurements showed an excellent corrosion resistance for Ti in medium solution, whereas, the corrosion resistance for Al was found to be very low in medium solution. In the investigations of the colony formation of V79 cells, well formed colonies were observed for Ti with mirror-like finishing, but, no colony exists in the case of Al with mirror-like finishing. However, the colony appeared when the plate was etched with NaHCO3 and C2H4O2. Also, a similar result was observed when the plate is polished with #240 water proof emery paper. Hence, the colony formation of V79 cells strongly depends on the surface treatment of Al plate. The oxide film formed on the surface of Ti and Al after 0.6 Ms(7 d) of incubation with V79 cells were investigated by X-ray photo electron spectroscopy. It was observed that, the peak for Ca and P were observed for Ti. On the other hand, such peaks were small for Al. The peaks for Ti resembles the peaks of those of hydroxyapatite, thus exhibiting excellent biocompatibility. It is important to note that no peak resembling hydroxyapatite was observed for Al.
