Improving the in vitro cell differentiation and in vivo osseointegration of titanium dental implant through oxygen plasma immersion ion implantation treatment

Abstract Titanium (Ti) is widely used in dental implants; however, the bioinert surface has been shown to limit osseointegration, particularly in patients with poor bone quality. This study created a thin bioactive oxide film on Ti dental implants via oxygen plasma immersion ion implantation (OPIII) to improve bone cell differentiation and osseointegration. OPIII treatment was performed using low (1016 ions/cm2) and high (4 × 1017 ions/cm2) doses of oxygen ions. The Ti surfaces were characterized in terms of topography, wettability, chemical composition, and crystal structure. The differentiation of human bone marrow mesenchymal stem cells on OPIII-treated Ti surfaces was evaluated in vitro in terms of alkaline phosphatase (ALP) activity (early stage marker) and von Kossa staining (late stage marker). The osseointegration of OPIII-treated screw-type Ti dental implants in the femur of rabbits was evaluated in vivo using scanning electron microscope/backscattered electron imaging and histological staining at 4 weeks after implantation. OPIII treatment could induce a Ti oxide film on Ti surface without altering the surface topography, roughness or wettability. Higher oxygen ions dose increased the thickness of the surface Ti oxide film as well as the proportion of rutile phase titanium dioxide (TiO2) in the Ti oxide film. The OPIII-treated Ti surfaces presented higher ALP expression level, stronger von Kossa staining signal, and higher bone-to-implant contact. Note that all of these effects were more pronounced on surfaces created using higher oxygen ions dose due to the higher proportion of rutile phase TiO2. Overall, our results indicate that OPIII treatment using higher oxygen ions dose can enhance the in vitro bone cell differentiation and in vivo osseointegration of Ti dental implants.