The sand-blasting and acid etching (SLA) method can fabricate a rough topography for mechanical fixation and long-term stability of titanium implant, but can not achieve early bone healing. This study used two kinds of plasma treatments (Direct-Current and Radio-Frequency plasma) to modify the SLA-treated surface. The modification of plasma treatments creates respective power range and different content functional OH groups. The results show that the plasma treatments do not change the micron scale topography, and plasma-treated specimens presented super hydrophilicity. The X-ray photoelectron spectroscopy (XPS)-examined result showed that the functional OH content of the RF plasma-treated group was higher than the control (SLA) and DC treatment groups. The biological responses (protein adsorption, cell attachment, cell proliferation, and differentiation) promoted after plasma treatments, and the cell responses, have correlated to the total content of amphoteric OH groups. The experimental results indicated that plasma treatments can create functional OH groups on SLA-treated specimens, and the RF plasma-treated SLA implant thus has potential for achievement of bone healing in early stage of implantation.

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Titanium alloy (Ti6Al4V) has widespread medical applications because of its excellent biocompatibility. Its biological responses can further be enhanced by polishing and passivation. Unfortunately, preparing titanium alloy samples of nanometric roughness is by far much more difficult than preparing those of micrometric roughness, and numerous investigations on roughness induced effects are all focused on micrometric scales. For the remedy, we investigate, at nanometric scale, the influence of roughness on surface properties and biological responses. Six groups of Ti6Al4V with average roughness (R(a)) values of 2.75-30.34 nm are prepared. The results indicated that nanometric roughness of samples change the wettability and amphoteric OH groups. The contact angles monotonically decrease from 2.75 to 30.34 nm and the rougher surfaces lead to higher wettability. The in vitro cell-culture studies, using Murine NIH-3T3 fibroblasts, showed the spindle-shaped morphology on rougher surface compared to round∕spherical morphology on smoother surface. A cytodetacher is employed to quantitatively measure the initial adhesion force of fibroblasts to specimen. The adhesion strength of fibroblasts, ranging from 55 to 193 nN, is significantly influenced by the nanometric roughness while the surface is within the range of 2.75-30.34 nm R(a) roughness, and the adhesion strength appeared stronger for rougher surface. The cell number on the smoother surface is higher than on the rougher surface at 5-day culture. The studies indicated that nanometric roughness would alter the surface properties and further influence cell morphology, adhesion strength, and proliferation.

Background/purpose The surface properties, such as hydrophilicity and functional OH groups, play an important role in bone fixation in vivo . In our previous study, the plasma treatments of large grit and acid etching (SLA) method produce functional OH groups on the rough surface. There is no report in discussing the integration between basic Ti—OH groups and bone-to-implant contact (BIC). The aim of this study was to evaluate the effect of the functional OH groups on the rough surface both in vitro and in vivo . Materials and methods Functional hydroxyl groups were produced on a SLA-treated surface. The surface topography, roughness, wettability, and chemical composition were examined using various techniques. Twenty-four implants were inserted into the proximal tibia of four New Zealand white rabbits. The biological responses were measured in terms of histomorphometric analysis 4 and 8 weeks post-implantation. Results The surface morphology and roughness were similar among all groups. However, the concentration of OH groups and hydrophilicity were found increased in the plasma treatment. The cell morphology in RF-plasma treated groups had more polygonal type and higher expression of actin and vinculin. The bone-to-implant contact (BIC) ratios of RF-200W were significantly higher than other groups ( P < 0.05). The relationship between basic OH groups and BIC showed linear correspondence. Conclusion The Ti—OH groups introduced on the rough surface by plasma treatments can trigger cell adhesion which further initiate new bone apposition. We propose that RF-plasma treatment can help to enhance bone healing at 4 and 8 weeks.