A particulate glass for a synthetic bone (including dental) graft includes ZnO, SrO, and may include NaO. The glass promotes cellular metabolism, and upon implantation in living bone tissue induces bone growth at their surface. The ZnO and SrO respectively degrade to provide Zn.sup.2+ and Sr.sup.2+ ions respectively. The ions released by the glass provide anti-bacterial effects; improved bone formation in place of diseased tissue; inhibition of bone resorption; and radiopacity. There is excellent synergy between the SrO, ZnO, and NaO. The Sr.sup.2+ ions have better bone formation effects than the Zn.sup.2+ ions, but an anti-bacterial effect which is not as good. Choice of relative proportions of ZnO and SrO combined with the choice of NaO concentration to set the resorption rate allow optimisation. NaO there is control of the degradation rate of the graft; a feature which is advantageous in tailoring the grafts to specific patients and applications. Additionally the sodium (Na) in the glass imparts water solubility, allowing glasses to degrade to their ionic components.