Enhanced Bioactivity and Osteoblast Viability on Calcium Soaked Titanium Oxides
Objectives: To compare the bioactivity and assess osteoblast attachment and functionality for phosphorous containing oxide layers with and without calcium soak treatment. Methods: Commercially pure titanium samples (n=6) were anodized in two electrolytes with a DC rectifier using 12V, 10s steps to a final voltage of 108V. Thin film X-ray diffraction was used to determine oxide phases present. Samples (n=3) from each group were soaked for 72 hours at 80°C in a 1.2M calcium nitrate tetrahydrate solution. Energy dispersive spectroscopy was used to analyze surface chemistry. Bioactivity testing was performed for 7 days according to ISO standard 23317. Samples (n=3) with and without calcium treatments were seeded with approximately 40,000 MC3T3-E1 pre-osteoblasts/cm2, and live/dead assays were performed at days 7 and 21. A DNA assay was performed at days 0, 7, 14, and 21, and an ANOVA (α = 0.05) with post hoc Tukey analysis was used to compare results. Results: One electrolyte produced an anatase oxide with a Ca/P ratio of 1.89, while the other produced an amorphous layer with a Ca/P ratio of 1.84. All calcium soaked samples revealed enhanced apatite formation. All samples showed confluent cells that were more than 95% alive by live/dead assay. DNA testing revealed no significant differences at day 7 or 14, but did show significantly lower values for soaked versus non-soaked amorphous oxides at day 21 (p=0.008) Conclusions: A calcium soak treatment enhanced bioactivity on a phosphorous containing anatase layer without compromising osteoblast attachment.