Biocompatibility of Hydroxyapatite Films Formed on Ti Metal by a Simple Urea and Urease Treatment

HAp films with good adhesive property were formed by a simple surface treatment utilizing an enzyme reaction of urea with urease. The resulting coating layer consisted of carbonate-containing HAp with poor crystallinity. The in vitro evaluation using osteoblastic cells showed that HAp-coated Ti substrate had a good cellular response, such as cell proliferation and differentiation into osteoblast. From the results of in vivo evaluation using rabbit models, the HAp-coated Ti substrate directly bonded to bones to form large amount of new bone around implant. It has been found from both the in vitro and in vivo evaluations that the present HAp-coated Ti substrate has excellent biocompatibility.