Abstract: A method is disclosed for preparing an improved bioreactive material of the glass or partially crystallized glass type for bone prostheses or dental implants, which can be welded to bone tissue by chemical bonding. The material consisting essentially of, by weight, 5 to 14% Na.sub.2 O, 0 to 12% P.sub.2 O.sub.5, 49 to 57% SiO.sub.2, and balance, no more than 33% CaO+CaF.sub.2, the material containing 0.5 to 7% CaF.sub.2, and is prepared by a method comprising the steps of preparing a mixture of powders constituting a precursor of the material made of carbonates, phosphates, silica, oxides and fluorides, melting, homogenizing, casting and cooling the mixture to obtain an intermediate, non-crystallized glass, optionally annealing, and then grinding, either pressing the non-crystallized ground glass obtained cold to shape it, then sintering naturally or under a load after degassing, or sintering under a load directly after degassing, then cooling and optionally polishing or machining.