Biological performance of boron-modified bioactive glass particles implanted in rat tibia bone marrow.

The aim of the present study was to characterize the neoformed bone tissue around boron-modified bioactive glass particles implanted in rat tibia bone marrow by histologic, histomorphometric and microchemical evaluation. Melt-derived glasses were prepared from a base 45S5 bioactive glass of nominal composition (45% SiO2, 24.5% CaO, 24.5% Na2O and 6% P2O5 in wt%). The glass composition was modified by adding 2% wt of boron oxide (45S5.2B). Histological and histomorphometric analyses using undecalcified sections showed that at 15 days post-implantation the area of neoformed bone tissue around the 45S5.2B particles was significantly higher than control 45S5 glass. No statistically significant differences were observed at 30 days post-implantation. The thickness of osseointegrated tissue on 45S5.2B BG particles was significantly greater than on the control at all experimental time-points evaluated. A statistically significant increase in the Ca:P ratio was observed in the neoformed bone around 45S5.2B particles 15 days post-implantation. The results of the present study provide evidence that particles of boron-modified 45S5 BG (45S5.2B) enhance bone formation more than 45S5 glass when implanted into the intramedullary canal of rat tibiae.