Image and numerical analyses for understanding the in vivo dissolution of partially crystalline bioactive glass S53P4 scaffolds

This work employs image and numerical analyses of SEM micrographs to understand the fate of partially crystallized S53P4 scaffolds after implantation in rabbit femurs for 2, 4, and 8 weeks. Bioactive glasses commonly used for the regeneration of bone tissue may crystallize during hot-working, which affects their dissolution. The in vivo degradation behavior of the scaffolds was analyzed from cross-sectional SEM images by separating surface reaction layers, unreacted glass, and ingrown bone. The partial crystallization resulted in scaffolds degrading rapidly without decreasing size, thus enabling image analysis to estimate the progress of the in vivo behavior. The analysis enabled numerical estimates for the dissolution of sodium and silicon from the glass scaffolds. After 56 days, 68 % of silicon and 90 % of sodium had dissolved from the original sintered scaffolds. It was estimated that if the degradation continued similarly, all sodium would dissolve within three months and silicon in eight months.