Calcium-phosphate surface coating by casting to improve bioactivity of titanium.

In order to improve the bioactivity of titanium, an original surface treatment was attempted with the use of a casting technique was attempted. Pure titanium was cast into a special graphite mold in which the cavity wall was coated with hydroxyapatite (HA) powder. According to analyses of X-ray diffraction and EDX, the existence of HA and CaO and uptake of Ca and P on the surface of the titanium castings were identified. By immersing the specimen in Hank's solution, the concentrations of Ca and P on the surface increased with immersion time, and the formation of a thin layer with characteristics of spherical HA precipitates was observed after 1 week. The concentrations of Ca and P elements and the Ca/P ratio on the HA layer increased with immersion time. The formation of the HA layer on the titanium cast by this treatment was significantly accelerated compared with pure titanium. The present surface treatment of Ti is expected to improve early bone fixation of Ti implants. Copyright 2001 John Wiley & Sons, Inc.