There is accumulating evidence that strontium-containing biomaterials have positive effects on bone tissue repair. We investigated the in vitro effect of a new Sr-doped bioactive glass manufactured by the sol-gel method on osteoblast viability and differentiation. Osteoblasts isolated from foetal mouse calvaria were cultured in the presence of bioactive glass particles; particles were undoped (B75) or Sr-doped with 1 wt.% (B75-Sr1) and 5 wt.% (B75-Sr5). Morphological analysis was carried out by contrast-phase microscopy and scanning electron microscopy (SEM). Cell viability was evaluated by the MTS assay at 24 h, 48 h and 72 h. At 24 h, day 6 and day 12, osteoblast differentiation was evaluated by assaying alkaline phosphatase (ALP) activity, osteocalcin (OC) secretion and gene expression of various bone markers, using Real-Time-PCR. Alizarin Red staining and ALP histoenzymatic localisation were performed on day 12. Microscopic observations and MTS showed an absence of cytotoxicity in the three investigated bioactive glasses. B75-Sr5 particles in cell cultures, in comparison with those of B75 and B75-Sr1, resulted in a significant up-regulation of Runx2, Osterix, Dlx5, collagen I, ALP, bone sialoprotein (BSP) and OC mRNA levels on day 12, which was associated with an increase of ALP activity on day 6 and OC secretion on day 12. In conclusion, osteoblast differentiation of foetal mouse calvarial cells was enhanced in the presence of bioactive glass particles containing 5 wt.% strontium. Thus, B75-Sr5 may represent a promising bone-grafting material for bone regeneration procedures.

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IT and mucosal tissue thickness did not influence marginal bone loss. Buccal bone thickness of ≥2 mm was associated with a minimal marginal bone remodeling.

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Studying the local release of strontium traces in vivo is of key interest, but calls for highly sensitive techniques besides providing an excellent (micronic) spatial resolution. In this context nuclear microprobes such as the PIXE (Particle-Induced X-ray Emission) technique, appear as powerful tools of investigation. Here, the in vivo behaviour of a Sr-delivering bioactive glass has been investigated through micro-PIXE analyses in connection with histological studies. New bone formation is observed after 6 weeks of implantation in rabbit femoral condyle. Interestingly, Sr traces are detected over a large area at the site of implantation, demonstrating the efficient release of Sr osteo inductive ions from the glass and their diffusion over several ten microns through the tissues. From its inorganic composition and content in traces of interest such as Zn, neo formed bone seems of higher quality for Sr-delivering particles compared to Sr-free particles, evidencing the positive effect of Sr in vivo.