Enhancement of valve metal osteoconductivity by one-step hydrothermal treatment

• Hydrothermal treatment in distilled water was applied to valve metals.
• Surface characteristics and osteoconductivity by in vivo test were evaluated.
• Water contact angles of valve metals were decreased by hydrothermal treatment.
• Osteoconductivity of valve metals improved notably by hydrothermal treatment.

In this study, we produced super-hydrophilic surfaces of valve metals (Ti, Nb, Ta and Zr) by one-step hydrothermal treatment. Their surface characteristics and osteoconductivity using an in vivo test were then assessed. These data were compared with that of as-polished, as-anodized and both anodized + hydrothermally treated samples. Changes in surface chemistry, surface morphology and structure were investigated by X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffractometry. The results revealed that the water contact angles of valve metals were decreased by hydrothermal treatment and continued to reduce dramatically until lower than 10° after being immersed in phosphate buffered solution. By producing super-hydrophilic surfaces, the osteoconductivity of these hydrothermally treated valve metals was enhanced by up to 55%.