METHODS: Polished titanium discs (10x10x5mm) were pre-treated with 30% H2O2 (5ml H2O2/g disc) at room temperature for 0, 1, 3, 6 or 24h and 1, 2 or 4wks. Treated discs (3 discs/treatment) were subjected to AFM, SEM and Profilometric analysis. For protein adsorption analysis, Fluoroscein isothiocyanate (FITC)-conjugated human serum albumin (40mg/ml) was added to untreated (control) and H2O2-treated titanium disc surfaces (3 discs/treatment), incubated at 37°C/1min and examined by Fluorescent Microscopy.
RESULTS: AFM, SEM and Profilometry demonstrated that 1-6h-treated titanium discs exhibited only subtle alterations in surface topography, compared to smooth, untreated discs. In contrast, 24h-treated discs exhibited more obvious topographical alterations, with a fibrous-like network. Greater alterations in surface topography/roughness were observed in 1-4wk treated discs. Surface roughness (Ra) increases were confirmed at each H2O2-treatment, being significantly higher to controls at 24h (p<0.01) and 1-4wks (p<0.001). FITC-conjugated serum albumin adsorption demonstrated increased albumin surface coverage to controls on 1-24h H2O2-treated discs, with further increases on 1-4wk-treated discs.
CONCLUSIONS: As an optimal surface roughness range to enhance protein and cellular adsorption/adherence is well-established, it appears that H2O2 pre-treatments of above 24h are necessary to induce surface roughness increases, improving osseointegration. However, as extremely rough surfaces are acknowledged to impair cellular adherence, and serum albumin is non-adhesive to osteoblasts, further investigations are required to determine whether such longer-term H2O2 pre-treatments are beneficial to osteoblast adherence and activity?