In vivo histological response to anodized and anodized/hydrothermally treated titanium implants

In the study, characterization of the anodized titanium surface was performed. In addition, histological evaluation and interfacial strength at the bone-implant interface of the characterized surfaces were then evaluated with the use of a rabbit model at 6 and 12 weeks after implantation. Surface treatments consisted of either anodization or anodization followed by hydrothermal treatments. Nontreated titanium surfaces were used as controls in this study. Using scanning-electron microscopy, porous oxide layers were observed on surfaces of anodized titanium implants, whereas porous oxide layers and HA needles were observed on anodized titanium implants following hydrothermal treatments. X-ray diffraction analysis showed the oxide layers were consisted mainly of anatase and a little of rutile. By the hydrothermal treatment on the anodizing surface, HA peaks, as well as the peaks of anatase and trace amounts of rutile peaks were observed. In EPMA analysis, the Ca/P ratio for the anodic oxide was 1.54 for anodized surfaces, whereas the Ca/P ratios for HA needles and the anodic oxide were 1.64 and 0.57, respectively, for anodized surfaces following hydrothermal treatments. Although no significant difference was observed for the percent bone contact on all implants evaluated in the in vivo study, the removal torque strength was significantly higher for anodized implants (48.02+/-5.92 N/cm) than the untreated implants (controls) (27.83+/-1.78 N/cm) at 6 weeks after implantation. As such, it was concluded that the surface anodized implants resulted in a high interfacial strength at an early implantation period as compared to the nontreated titanium implants.