Research Article
Kato Y, Ito A, Hattori T, Ak
Abstract
By means of X-ray follow-up and Contact Micro Radiography (CMR), new bone formation around the implants was investigated. And cytopathological observation was performed on the surrounding tissue. Regarding to the implants, microscopic observation was performed on the removed implants surface. Furthermore, metal element analysis was carried out to investigate chromium ion release as a sign of the galvanic corrosion. In order to investigate the in-vivo galvanic corrosion, the plates and screws made of SUS and Ti64 were implanted into the proximal tibia of the rabbits for 52 weeks. The plate and screws were implanted in 4 different combinations of pairing up in different metals and identical metals By means of X-ray follow-up and Contact Micro Radiography (CMR), new bone formation around the implants was investigated. And cytopathological observation was performed on the surrounding tissue. Regarding to the implants, microscopic observation was performed on the removed implants surface. Furthermore, metal element analysis was carried out to investigate chromium ion release as a sign of the galvanic corrosion. In X-ray follow-up and CMR, the bone tissue under the plates became thin and porous like as concellous bone in all the combinations, which is supposedly due to the stress shielding and the disturbance of periosteal blood flow by the implantation. In the surrounding soft tissue and bone tissue, no remarkable findings were obtained in the cytopathological observation. Regarding to microscopic observation of the implants, short striations with metallic luster in SUS implants, and short striations with metallic luster or dark brown color in Ti64 implant were confirmed. However these are supposedly caused by the scratching or frictional damage during the screw fixation. In metal element analysis, the Cr element elution was confirmed around the SUS plates. However, there is no significant difference between SUS screw (identical metals) and Ti64 screw (different metals). As the results, the in-vivo galvanic corrosion and related changes were not confirmed in all investigations at 52 weeks.