Abstract: Regenerated and reconstructed bone and tooth material which is well tolerated by the body and can be implanted without any danger of rejection is obtained by first demineralizing natural bone or tooth material obtained, for instance, from animals, converting said demineralized material into a mucopolysaccharide-free colloidal solution, adding to said solution a physiologically inert foreign mucopolysaccharide, gelling said solution, and remineralizing the resulting gel.