Calcium-phosphate formation on titanium modified with newly developed calcium-hydroxide-slurry treatment

Authors developed a new surface-modification method with calcium-hydroxide slurry, which make it possible to treat a titanium surface by contacting with an alkaline agent containing high concentration of calcium. The objective of the new surface modification method was to improve a bone conductivity of titanium with simple and low-cost processes. The calcium-hydroxide slurry was prepared by mixture of calciumhydroxide regent and deionized water. A titanium plate was completely buried in the calcium-hydroxide slurry, and the slurry including the titanium was heated in air at 873 K for 7.2 ks, followed by washing in deionized water, and drying in air. Characterization with X-ray photoelectron spectroscopy revealed that chemical state of the surface-modified-titanium surface was the same as that of calcium titanate. X-ray diffraction pattern showed that the perovskite-type calcium titanate was formed in the surface-modified layer, and depth profile by Auger electron spectroscopy titanium indicated that dioxide layer was formed under the calcium-titanate layer. When the surface-modified titanium was immersed in a Hanks' balanced saline solution for 9d, hydroxyapatite was formed on the surface-modified- titanium surface, while was not formed on the unmodified-titanium surface without surface modification. However, after 18-d immersion, hydroxyapatite was also formed on unmodified-titanium surface. X-ray diffraction pattern showed that thickness of the hydroxyapatite layer formed on the surface- modifiedtitanium surface was thicker than that on the unmodified-titanium surface. These results indicated that the calcium-hydroxide-slurry treatment improves the performance of calcium-phosphate formation of titanium. Therefore, the new treatment technique is one of the promising methods for improvement of bone conductivity of titanium.