Osteoconductivity of hydrophilic microstructured titanium implants with phosphate ion chemistry

This study investigated the surface characteristics and bone response of titanium implants produced by hydrothermal treatment using H₃PO₄, and compared them with those of implants produced by commercial surface treatment methods - machining, acid etching, grit blasting, grit blasting/acid etching or spark anodization. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, contact angle measurement and stylus profilometry. The osteoconductivity of experimental implants was evaluated by removal torque testing and histomorphometric analysis after 6 weeks of implantation in rabbit tibiae. Hydrothermal treatment with H₃PO₄ and subsequent heat treatment produced a crystalline phosphate ion-incorporated oxide (titanium oxide phosphate hydrate, Ti₂O(PO₄)₂(H₂O)₂; TiP) surface approximately 5 μm in thickness, which had needle-like surface microstructures and superior wettability compared with the control surfaces. Significant increases in removal torque forces and bone-to-implant contact values were observed for TiP implants compared with those of the control implants (p < 0.001). After thorough cleaning of the implants removed during the removal torque testing, a considerable quantity of attached bone was observed on the surfaces of the TiP implants. Crown