Surface Hydrophilicity and Osteoconductivity of Anodized Ti in Aqueous Solutions with Various Solute Ions

Abstract

Surface hydrophilicity is considered to have a strong influence on the biological reactions of bone substituting materials. However, the relationship between hydrophilicity and osteoconductivity has not been discussed quantitatively. In this study, Ti substrates were coated with TiO₂ having different water contact angles, using anodizing in aqueous solutions containing different types of solute ion, and the quantitative relationship between hydrophilicity and osteoconductivity was investigated.
All of the anodized coatings were anatase-type TiO₂ with a fine surface roughness. Most of the solute ions were included in the coatings, but they did not influence the hydrophilicity of the anodized coatings. However, the surface hydrophilicity of the anodized coatings depended on the pH of the aqueous solution. The amount of hard tissue formed on TiO₂-coated specimens (denoted as R_B-I) depended on the water contact angle on their surface. For water contact angle between 20 (deg.) and 55 (deg.), the value of R_B-I increased as water contact angle decreased. On the other hand, for water contact angle between 55 (deg.) and 70 (deg.), the value of R_B-I increased as water contact angle increased.