Formation and Osteoconductivity of Hydroxy apatite/Collagen Composite Films Using a Thermal Substrate Method in Aqueous Solutions

摘要

We have studied the formation and carried out an in vivo evaluation of hydroxyapatite (HAp)/collagen and HAp/denatured collagen (gelatin) composite coatings on titanium substrates using a thermal substrate method. The coatings were formed on commercial pure titanium rods (diameter = 2 mm, length = 5 mm) and plates (thickness = 0.3 mm) using a thermal substrate method in aqueous solutions that contained 0.3 mM Ca(H_2PO_4)_2, 0.7 mM CaCl_2, and a concentration of acid-soluble collagen (Type I) of approx 432 mg dm~(-3). The coating experiments were conducted at 40-140°C and pH = 8 for periods of 15 or 30min. The coating temperature and collagen content in the solution influenced the surface morphology and collagen (or gelatin) content in the films, A coated rod was implanted in a 10-week-old male rat's tibia with a non-coated titanium rod being used as a control. The constructs were retrieved after a period of 14d postimplantation and examined for new bone formation and for tissue response in the cancellous and cortical bone parts, respectively. HAp/gelatin composite films coated at > 60 deg C showed a slight improvement in osteoconductivity in the cortical bone. In contrast, there was no improvement in the cancellous bone, compared with HAp, which had no gelatin. However, the HAp/collagen composites showed a high osteoconductivity in the cortical bone region, and this increased with increasing collagen content in the films. There was the same tendency in the cancellous bone part. However, too higher a collagen content (40mass percent ) in the films gave rise to an obvious negative osteoconductive effect.