The invention relates to the use of ions of weakly basic oxides as linking ions for polyacids in cements, preferably polyelectrolyte cements. Suitable ions comprise elements of the scandium series, for example, Sc.sup.3+, Y.sup.3+, La.sup.3+, Ce.sup.4+ and all subsequent tri- and tetra-valent lanthanides and the ions Mg.sup.2+, Zn.sup.2+, Ga.sup.2+, In.sup.2+. The application of said ions permits a regulation of the cement reaction without surface treatment of the glass powder.