Figure 2. Schematic representation of the first, second, third, fourth and fifth hypotheses, respectively. First hypothesis: Constant low pH caused by sucrose fermentation would release ions from mineral deposits, which could diffuse to saliva, and promote dental plaque with lower inorganic ion concentrations. However, after 10–12 hrs, there would have been enough time for the mineral ions, which had been lost to saliva, to be replaced by the simple law of mass action. Second hypothesis: Enamel could have taken up ions from biofilm fluid during pH-cycling. After 12 hrs, the biofilms would have been again saturated with these ions. Third hypothesis: Schematic representation adapted from Rose et al.(1996). Binding to bacterial cell wall is another reservoir of minerals. When the pH falls, the minerals are released from biofilm. After the pH is increased, the biofilm is saturated again with the ions from saliva. Fourth hypothesis: Bacterial density. Note that, in the second circle, the density of bacteria is lower, since polysaccharides occupy a large volume of the biofilm. Fifth hypothesis: Low concentrations of specific ion-binding proteins. It has been suggested that biofilm formed in the presence of sucrose shows fewer calcium-binding sites for proteins.