[Oral streptococci affecting Ca-phosphate precipitation]

The precipitation of Ca-compounds in ageing dental plaque leads to the formation of calculus. Bacterial lipoteichoic acid (LTA) has been discussed as Ca-carrier in this process (Zoon et al., 1989). Therefore in this study, LTA was isolated from oral streptococci and tested for its influence on the precipitation of Ca-phosphate. LTA-containing bacteria, LTA-free bacteria and isolated LTA were added to the reaction mixtures for Ca-phosphate precipitation and the amount of precipitated mineral was measured. LTA-containing cells and, above all, LTA, inhibited Ca-phosphate precipitation in a distinct pH-range just above the acid solubility of the mineral by complexing Ca(2+)-ions. Experiments with Ca-fluoride in place of Ca-phosphate showed that LTA did not affect the precipitation of this mineral.