34. Surface Modification with Hydrophilization

Corrosion-resistant valve metals, such as Ti, Nb, Ta, and Zr, and their alloys have attracted much interest as bone substitutes in dental and orthopedic fields. However, in their pure form, these metals and alloys do not always encourage hard-tissue growth on their surface in living bodies. Surface characteristics always influence the biological response at the interface between the implants and body tissues. Titanium dioxide (TiO₂) is known as an osteoconductive material and it has been shown to exhibit strong physicochemical fixation with living bone. In this paper, our experimental results using anodized TiO₂ coatings are briefly outlined, including their in vivo evaluation. Based on these results, a comprehensive description of the factors that influence osteoconductivity with respect to the surface characteristics of the implants is presented, and a new approach to controlling the osteoconductivity of Ti and other valve metals and their alloys by using hydrothermal treatment is proposed. Furthermore, the hydrophilization of ceramics such as alumina and zirconia, and polymers such as polyetheretherketone (PEEK) and polyethersulfone (PES) is discussed. The protein adsorbability of the surface-treated samples and the osteoconductivity of the protein-adsorbed samples are also discussed.