Abstract
Titania (TiO2)/hydroxyapatite (HAp) composite films were prepared on commercially pure titanium rods (2 mm in diameter, 5 mm in length) by anodic-cathodic pulse electrolysis in an aqueous solution consisting of 0.3 mM Ca(H2PO4)2 and 0.7 mM CaCl2 and pH=5.5. The electrolysis was carried out in an autoclave at 120°C for 30 min. using +8.7 V vs. Ag/AgCl sat. KCl as the anodic potential and −9.3 V as the cathodic potential, and changing the electrolysis cycle (60∼600 s) and duty ratio. We obtained TiO2/HAp composite films in which fine HAp particles were uniformly dispersed on a thin TiO2 layer. The coated rods were implanted in the tibiae of 10-week-old male rats. The constructs were retrieved 14 days postimplantation and examined for new bone formation and tissue response in the cancellous and cortical bone. They were compared with HAp-coated titanium rods, TiO2-coated rods (anodizing in an aqueous solution), TiO2/HAp-coated rods formed by the high temperature oxidization of specimens coated with HAp by cathodic electrolysis, and uncoated titanium rods. Fourteen days after implantation, new bone had formed on all the coated samples (HAp, TiO2, and TiO2/HAp) and noncoated titanium rods in the cancellous bone and cortical bone. In particular, TiO2/HAp composite films prepared by pulse electrolysis had very high osteoinductivity, which resulted from a synergistic effect of HAp and TiO2 on the bioactivity.
