Effect of in situ plaque mineral supplementation on the state of saturation of plaque fluid during sugar-induced acidogenesis

Dental plaque fluid is normally supersaturated with respect to enamel miner al but this may change to a state of undersaturation when plaque pH falls f ollowing sugar exposure, placing the adjacent enamel at risk of caries. We have determined the saturation status of the fluid in both resting and ferm enting plaque following mineral supplementation. Eleven subjects abstained from oral hygiene and rinsed their mouth 3 times/d for 3 d with a placebo s olution or with test solutions designed to enrich plaque with hydroxyapatit e or fluorhydroxyapatite. On the morning of day 4, plaque samples were coll ected before and after exposure to 10% sucrose. Compared to the placebo, us e of the test rinses resulted in significantly higher concentrations of Ca, P and F in plaque residue. In plaque fluid, higher post-sucrose Ca-free(2) concentrations and saturation levels with respect to enamel mineral and f luorapatite were found after use of the hydroxyapatite rinse compared to th e placebo, effects that probably resulted from the release of cell-bound Ca 2+ as well as from the dissolution of apatite. Thus, some evidence was obta ined that the test mouthrinses can counteract the fall in saturation level found when plaque is exposed briefly to sucrose. Potential long-term benefi ts of the test mouthrinses deserve further study.