In this study, we test the hypothesis that (1) bioactive glasses (50-59 wt.% SiO2, used for coating Ti/Ti alloy) enhance the attachment and proliferation of osteoblasts and (2) that this enhanced behavior is partially owed to the release of ions from the glass surface. In vitro testing included pH and dissolution rate determination in simulated body fluid (SBF) along with in vitro cyto compatibility testing. Experimental bioactive glass (6P55, 55 wt. % SiO2) and commercial Bioglass (45S5, 45 wt. % SiO2), demonstrated t ½ dependence and maximum pH of approximately 8.1 after 10 days of immersion. The dissolution rate of these glasses approached 0 after 15 days of immersion, which resulted in pH stabilization at less than 7.5. Cell culture studies showed that both glasses (6P55 and 45S5) behaved in a similar fashion with a 1.5x and 1.8x increase, (as compared to control) respectively, in cell density after 16 hours in culture, whereas commercial Ti alloy had an increased cell density of 1.2x compared to control. The effect of glass dissolution on osteoblast activity was isolated by culturing MC3T3 E1.4 cells in materials extract . The materials extract was prepared by soaking (48 h) sterilized bioactive glasses in  MEM (which was sterile filtered (0.2 µm) and then supplemented by 10% fetal bovine serum and 1% penicillin streptomycin) and added to to MC3T3 E1.4 cells in vitro. Cells proliferated approximately 2x in the presence of materials extract as compared to control (cell culture media), thus indicating that this enhanced osteoblast behavior is partially owed to the presence of the dissolution products of bioactive glasses.

Support. NIH/NIDCR Grants R01DE11289 and T32DE07306 (VV).