Bioactivity of tape cast and sintered bioactive glass-ceramic in simulated body fluid.

A common ceramic processing technique, tape casting, was used to produce thin, flexible sheets of bioactive glass (Bioglass 45S5) particulate in an organic matrix. Tape casting offers the possibility of producing three-dimensional shapes, as the final material is built up layer by layer. Bioactive glass tapes were sintered together to form small discs for in vitro bioactivity testing in simulated body fluid (SBF). Four different sintering schedules were investigated: 800, 900, and 1000 degrees C for 3 h; and 1000 degrees C for 6 h. Each schedule produced a crystalline material of major phase Na2Ca2Si3O9. Tape cast and sintered bioactive glass-ceramic processed at 1000 degrees C formed crystalline hydroxyapatite layers after 20-24 h in SBF as indicated by Fourier transform infrared spectroscopy, Scanning electron microscopy, and EDS data. FTIR revealed that the greatest amount of hydroxyapatite formation after 2 h was observed for samples sintered at 900 degrees C. The differences in bioactive response were likely caused by the variation in the extent of sintering and, consequently, the amount of surface area available for reaction with SBF.