Microchemical analysis of bioactive glass particles of narrow size range

摘要

Previous studies demonstrated the capacity of bioactive glass particles (BG) of narrow size range (300-355 mu m, Biogran~circleR) to stimulate the formation of new bone tissue by the formation of protective pouches. In these pouches, formation of new bone is detected without this bone being connected to the bone tissue outside the particles. These islands of newly formed bone tissue act as nuclei for enhanced bone repair. This osteostimulatory effect is a consequence of the chemical interactions between the bioactive glass and the surrounding tissue fluids. This study evaluates the chemical transformation of these bioactive glass particles. The particles are implanted in the jaws of beagle dogs and resected after 1, 2, 3, 6, 12 months. Microchemical analysis is performed using a scanning electron microscope equipped with an Energy Dispersive X-ray analysis system. The results show that after 1 month Na-ions are completely leached out and that the particle is transformed into a dual reaction layer; the centre is turned over into a Si-rich gel, while the outer surface consists out of a CaP-rich shell. After 2 months the concentration levels of the CaP-rich shell remain, while in the centre the Si-concentration decreases and the Ca- and P-concentrations increase. Histologically, phagocytosis of the Si-gel, resulting in excavated particles, is observed. These tendencies continue after 3 months and after 6 months Si has disappeared completely, while the Ca- and P-concentrations in the centre and in the outer shell are similar. At this time, bone formation in the excavated area is noticed. After 1 year the Ca- and P-concentrations in the transformed particles equal those of the bone tissue, further confirming the biological equivalence of the CaP-shell and bone tissue.