The effect of plasma chemical oxidation of titanium alloy on bone-implant contact in rats

Many different technologies have been used to enhance osseointegration in orthopaedic and dental implant surgery. Hydroxyapatite coatings, pure or in combination with growth factors or bisphosphonates, showed improved osseointegration of titanium alloy implants. We choose a different approach to enhance osseointegration: plasma chemical oxidation was used to modify the surface of titanium alloy implants. This technique converts the nm-thin natural occurring titanium oxide layer on an implant to a 4 μm thick ceramic coating (TiOB surface). Bioactive TiOB surfaces have a macroporous structure and were loaded with calcium and phosphorus, while bioinert TiOB surfaces are smooth. A rat tibial model with bilateral placement of titanium alloy implants was employed to analyze the bone response to TiOB surfaces in vivo. 64 rats were randomly assigned to four groups of implants: (1) titanium alloy (control), (2) titanium alloy, type III anodization, (3) bioinert TiOB surface and (4) bioactive TiOB surface. Mechanical fixation, peri-implant-bone area and bone contact were evaluated by pull-out tests and histology at three and eight weeks. Shear strength and bone contact at eight weeks were significantly increased in the bioactive TiOB group compared to all other groups. The results of plasma chemical oxidation in a rat model showed that the bioactive TiOB surface has a positive effect on implant anchorage by enhancing the bone-implant contact in normal bone.