Biological response of tissues with macrophagic activity to titanium dioxide

The titanium dioxide layer is composed mainly of anatase and rutile. This layer is prone to break, releasing particles to the milieu. Therefore, corrosion may cause implant failure and body contamination. We have previously shown that commercial anatase-titanium dioxide (TiO2-anatase) is deposited in organs with macrophagic activity, transported in the blood by phagocytic-mononuclear cells, and induces an increase in the production of reactive oxygen species (ROS). In this study, we evaluated the effects of rutile-titanium dioxide (TiO2-rutile). Male Wistar rats were injected i.p. with a suspension of TiO2-rutile powder at a dose of 1.60 g/100 g b.w. Six months postinjection, the presence of Ti was assessed in serum, blood cells, liver, spleen, and lung. Titanium was found in phagocytic mononuclear cells, serum, and in the parenchyma of all the organs tested. TiO2-rutile generated a rise in the percentage of reactive cells, which was smaller than that observed when TiO2- anatase was employed in a previous study. Although TiO2-rutile provoked an augmentation of ROS, it failed to induce damage to membrane lipids, possibly due to an adaptive response. The present study reveals that TiO2-rutile is less bioreactive than TiO2-anatase. (C) 2007 Wiley Periodicals, Inc.