In vitro dissolution of melt-derived 45S5 and sol-gel derived 58S bioactive glasses.

Effects of powder type, particle size (5-20 microm; 90-300 microm; 90-710 microm), and type of dissolution medium on the dissolution behavior of bioactive glasses were investigated in vitro using melt-derived 45S5 and sol-gel derived 58S bioactive glass powders. Dissolution studies were performed in simulated body fluid and in alpha-MEM based cell culture medium at 37 degrees C under dynamic conditions (1 Hz) for periods of 30 min, 1, 2, 4, 8, 17, and 22 h. The concentrations of elements dissolved from the glasses were evaluated using inductively coupled plasma analysis. The reacted powders were analyzed for bioactivity using Fourier transform infrared spectrometry to observe the formation of a calcium phosphate layer on the surface. The non-porous surfaces of melt-derived 45S5 glass powders exhibited lower dissolution rates and rate of surface layer formation than 58S gel-glass powders. The rates of dissolution for both types of powders were lower in culture medium, compared to simulated body fluid, and increased as the particle size decreased. Thus, particle size range, glass type, and powder volume fraction can be used as a means to control the release rate of active ions that stimulate the gene expression and cellular response for tissue proliferation and repair.