NMR spectroscopy of dental materials. II. The role of tartaric acid in glass–ionomer cements

D(+) tartaric acid is incorporated into glass–ionomer cements to control the setting properties. 13C NMR spectroscopy of the fluid cement pastes have shown that tartaric acid reacts more readily than the polyacid with the glass, and hence suppresses the premature gelation of the cement. As the cements set, the pH rises from ca. 1.25 to ca. 3 when tartaric acid is fully complexed. As the polyacid reacts the pH rises further to ca. 5.