[Preparation of thin hydroxyapatite layers on cp titanium through anodic oxidation followed with hydrothermal treatment].

To study the method of anodic oxidation followed by hydrothermal treatment for cp titanium and to know bone response to thin hydroxyapatite layers in vivo, commercially pure titanium plates were anodized at 200 V-400 V with direct electric current density no more than 50 mA/cm2 for 15 minutes in the electrolytic trough. beta-glycerophosphate sodium(0.03-0.04 M) and calcium acetate(0.2-0.3 M) were used as electrolytes. Then, titanium plates were hydrothermal treated in the autoclave for 2 hours at 280 degrees C-300 degrees C. Polishing and grit-blasting surface was used as control to learn bone response to thin layers. Twelve rabbits were evenly divided into 3 groups, each group was implanted with 12 implants into the rabbits femoral bone. After 4, 8 and 16 weeks, implants were taken out and collected respectively and were made grinding slices. The bone-implant interface was observed with light microscope. And the bone-implant interface of polishing and layered implants after 8 weeks implantation was observed with scanning electron microscope. The element contents at the interface of polishing and layered implants before and after 8 weeks implantation were detected with EDAX. Results showed that there was hydroxyapatite(HA) precipitated on the titanium surfaceamellae bone in 8 weeks for thin HA coatings, and no HA debris were found at the interfacial zone. In addition, Ca and P content on the hydrothermal treated implant surface increased much more after implantation than that of polished implants. It was concluded that anodic oxidation followed by hydrothermal treatment could precipitate thin hydroxyapatie layer on the surface of cp titanium, which could improve early formation of woven bone and accelerate woven bone transferring to lamellae bone at the implanted site.