Formation and in Vivo Evaluation of Carbonate Apatite and Carbonate Apatite/CaCO_3 Composite Films Using the Thermal Substrate Method in Aqueous Solution
We have studied the formation and carried out an <I>in vivo</I> evaluation of carbonate apatite (CO<SUB>3</SUB>-Ap) and CO<SUB>3</SUB>-Ap/CaCO<SUB>3</SUB> composite coatings on titanium substrates using the thermal substrate method. The coatings were formed on commercial pure titanium rods (diameter = 2 mm, length = 5 mm) and plates (thickness = 0.3 mm) by the thermal substrate method in an aqueous solution that contained Ca(H<SUB>2</SUB>PO<SUB>4</SUB>)<SUB>2</SUB>, CaCl<SUB>2</SUB>, and NaHCO<SUB>3</SUB>. The coating experiments were conducted at 40–140°C and pH=8 for periods of 15 or 30 min. The coating temperature and NaHCO<SUB>3</SUB> of the solution had a significant influence on the surface morphology (net-like, plate-like, needle-like, or sphere-like), the phase (single phase of CO<SUB>3</SUB>-Ap or binary phase of CO<SUB>3</SUB>-Ap and CaCO<SUB>3</SUB>), and the carbonate content in the precipitated films. A subsequent autoclave treatment also had an effect on the films. A coated rod was implanted in a 10 weeks old male rat's tibia with a non-coated titanium rod being used as a control. The constructs were retrieved after a period of 14 d postimplantation and examined for new bone formation and for tissue response in the cancellous and cortical bone parts, respectively. Single-phase sphere-like CO<SUB>3</SUB>-Ap had high osteoconductivity in the cortical bone region, and this increased with increasing carbonate content in the films. However, the osteoconductivity of the CO<SUB>3</SUB>-Ap/CaCO<SUB>3</SUB> composite coatings decreased with increasing total carbonate content.
- Materials transactions
Materials transactions 49(6), 1434-1440, 2008-06-01
The Japan Institute of Metals and Materials