Increased Ca Concentration in Dental Plaque Reduces Dental Demineralization

Objectives: Since mineral loss from dental hard tissues is a function of the saturation of the surrounding fluids with mineral ions, strategies to increase the calcium concentration (Ca) on dental plaque could reduce dental demineralization, but this has not been studied in details. In the present study, experimental plaque pre-treated with calcium at increasing concentrations was submitted to a short-term in situ caries model.
Methods: Fifteen volunteers wore palatal appliances containing enamel blocks which were kept in contact with S. mutans IB1600 cells (test plaque) pre-treated with 0, 1 or 10 mM Ca PIPES buffer, pH 7.0, during 30 min, when test plaque was collected for determination of calcium concentration in its solid and fluid phase. After, volunteers rinsed (1 min) with 20% sucrose solution as a cariogenic challenge, and waited 45 min for collection of blocks and determination of surface hardness loss (demineralization). In the test plaque, Ca concentration in the fluid phase was determinate using a micro-electrode and in solid phase, after acid-extraction, with Arsenazo III reagent.
Results: After 30 min in situ, Ca concentration in the solid phase of the test plaque (μmol/g) was significantly greater (p<0.05) in the group pre-treated with 10 mM (30.5 ±10.2) compared to 0 and 1 mM (17.5 ± 5.1, 25.4 ± 13.0, respectively). Same was observed in the fluid phase (0.6 ± 0.1, 1.2 ± 0.1, 4.7 ± 0.3 mM Ca, for groups treated with 0, 1 or 10 mM Ca, respectively). Significantly lower (p<0.05) demineralization was observed in the 10 mM Ca group (-19.9 ± 10.1), but no significant difference was observed between the 0 and 1 mM Ca groups (30.3 ± 13.3 and 29.6 ± 13.9, respectively).
Conclusions: The data suggest that the increase of Ca concentration in dental plaque is able to reduce enamel demineralization.