The structural evolution of Bioglass after implantation in the femoral defects

Abstract The structural evolution of Bioglass after implantation in the femoral defects was investigated. It indicates that Bioglass directly bonds with new mineralized bone tissue. The rapid releases of Na and Ca ions result in the transformation of Bioglass to the Si-rich layer, and the widths of the Si-rich layers gradually increase to 45 μm at 6 weeks, 100 μm at 12 weeks, and 135 μm at 24 weeks, respectively. The density loss during the transformation of Bioglass to the Si-rich layer is more than 21% after implantation of 6 weeks. The further releases of Ca and Na ions contribute to the disproportionation reaction of Q2 to Q0 and Q4 in the Si-rich layer. Isolated SiO4 tetrahedrons (Q0) are dissolved and absorbed by bone tissue, resulting in the degradation of Bioglass with a decrease in volume. Residual Q4 leads to a more polymerized silica network in the Si-rich layer and a decrease in bioactivity and biodegradation.