Mineral ions in the fluid of biofilms formed on enamel and dentine shortly after sugar challenge.

To test the effect of distinct solubilities of dentine and enamel on mineral ion concentration in the biofilm fluid during a sugar-induced pH drop, dental biofilms were formed in situ for 4 days on acrylic (control), dentine or enamel. On the 5th day, they were treated with water (control) or 20% glucose and collected 5 min later. Significantly lower pH values and higher calcium concentrations were found in the biofilm fluid after glucose exposure, without significant differences among the three substrates. During pH drop, biofilm reservoirs release calcium to the fluid, masking the differential solubility between enamel and dentine.