Comparison between sol-gel-derived anatase- and rutile-structured TiO2 coatings in soft-tissue environment.

The bioactivity of the surface reactive TiO(2) coatings for medical implants can be locally modified by CO(2) laser processing to match with the properties of surrounding tissues. The TiO(2) coatings heat-treated at 500 degrees C exhibit in vitro bioactivity. With further CO(2) laser treatment they exhibit enhanced in vitro bioactivity. The aim of this in vivo study was to compare the performance of heat-treated anatase-structured TiO(2) coatings with preheat-treated and CO(2) laser-treated rutile-structured coatings in terms of their ability to attach soft connective tissues. The coatings were characterized with TF-XRD and AFM. TiO(2)-coated discs were implanted in rats. The samples were analyzed with routine histology, SEM-EDS, and TEM. In both groups, already at 3 days, soft connective tissues were in immediate contact with the surface. No thick crystalline CaP layer was detected by SEM-EDS, but a thin amorphous CaP layer was detected by XPS. No gap between the cell membrane and the coating could be observed in TEM pictures. No differences were observed between the anatase- and rutile-structured coatings in terms of tissue responses. Further studies are needed to verify if the tissues are adherent to the surface of the implant.