Evaluation of bone response to titanium-coated polymethyl methacrylate resin (PMMA) implants by X-ray tomography

High-resolution three-dimensional data about the bone response to oral implants can be obtained by using microfocus computer tomography. However, a disadvantage is that metallic implants cause streaking artifacts due to scattering of X-rays, which prevents an accurate evaluation of the interfacial bone-to-implant contact. It has been suggested that the use of thin titanium coatings deposited on polymeric implants can offer an alternative option for analyzing bone contact using micro-CT imaging. Consequently, the aim of the current study was to investigate bone behavior to titanium-coated polymethylmethacrylate (PMMA) implants by micro-CT and histological evaluation. For the experiment titanium-coated PMMA implants were used. The implants had a machined threaded appearance and were provided with a 400-500 nm thick titanium coating. The implants were inserted in the right or left tibia of 10 goats. After an implantation period of 12 weeks the implants were retrieved and prepared for micro-computer tomography (microCT), light microscopy, and X-ray microanalysis. The micro-CT showed that the screw-threads and typical implant configuration were well maintained through the installation procedure. Overall, histological responses showed that the titanium-coated implants were well tolerated and caused no atypical tissue response. In addition, the bone was seen in direct contact with the titanium-coated layer. The X-ray microanalysis results confirmed the light microscopical data. In conclusion, the obtained results proof the final use of titanium-coated PMMA implants for evaluation of the bone-implant response using microCT. However, this study also confirms that for a proper analysis of the bone-implant interface the additional use of microscopical techniques is still required.