Fabrication of TiO₂ nanotubes on porous titanium scaffold and biocompatibility evaluation in vitro and in vivo

Porous titanium was modified by anodic oxidation and heat treatment method. Scanning electron microscopy and X-ray diffraction examinations revealed that the modified surface of porous titanium was covered by anatase nanotubes. In vitro, the bioactivity of specimens before and after modification was evaluated by immersing into the double-concentration simulated body fluid for 7 days. The porous titanium specimens were implanted into the femurs of dogs for 3 months. The osteointegration of the implants was investigated by push-out test and histological examination. The results showed that the porous titanium with anatase nanotubes has the superior ability of apatite formation and a higher push-out force when compared with the other implants. The histological analysis indicated that the implant with anatase nanotubes had excellent ability to facilitate the osteointegration in vivo.