The effects of oral rinses on enamel fluoride uptake, caries, and plaque pH in rats were investigated by use of (1) an acidic calcium phosphate solution (CPS) saturated with dicalcium phosphate dihydrate (DCPD) and (2) a 1% fluoride solution. Osborne-Mendel rats, 19 days of age, were randomly assigned to one of four mouth-rinse treatment groups, with the two consecutively administered rinses being: H2O-H2O; H2O-F; CPS-H2O; and CPS-F. The treatments were administered on days 1 through 4, and the animals were provided with a cariogenic challenge throughout the study. The groups treated with F exhibited significantly higher mean levels of enamel-bound F than did the non-F groups. Furthermore, CPS significantly increased uptake of F by enamel when used as an adjunct to the F treatment. The caries scores of the CPS-F and H2O-F groups were not statistically different; however, a strong negative correlation was observed between enamel F content and caries scores, indicating that as more F was incorporated into the teeth, less caries formation occurred. Despite the significant differences in enamel F and caries scores among some of the treatment groups, post mortem in situ plaque pH drop in response to a sucrose rinse showed no differences among these groups.

This investigation, comprising three studies, measured the effects of flushing with an acidic calcium phosphate solution (CPS) on the cariostatic benefits of fluoride. In the first two studies, the rats received fluoride in the drinking water (2.5 ppm F) after initiation of the caries challenge. In contrast, in the third study, the animals received treatments as oral flushing before initiation of the cariogenic challenge. In all three studies, rats that received CPS in conjunction with fluoride exhibited a numerically lower mean caries score than those that received H₂O in conjunction with fluoride. Moreover, in the third study, the group receiving oral flushing of CPS followed by NaF (10,000 ppm F) for 3 successive days exhibited a significantly lower incidence of dental caries and higher concentration of enamel-bound fluoride than did the group treated with a H₂O-NaF sequence. A significant negative association (––0.65) between fluoride and caries was noted when the dentition of all rats in the third study were considered.

Application of monocalcium phosphate monohydrate (MCPM) gel, which produces small amounts of dicalcium phosphate dihydrate in enamel, was previously shown to increase the enamel reactivity with fluoride (F). This study was conducted to determine whether the MCPM gel treatment is also effective in enhancing F uptake by root surfaces of human teeth. The results show that samples receiving daily treatments with MCPM gel for 10 min followed by immersion in a 1-ppm F solution for 5 days acquired a significantly greater amount of F compared to the controls which had the same exposure to the F solution. Because the F solution was undersaturated with respect to calcium fluoride (CaF₂), the F incorporated into the root is apparently apatitic and not CaF₂. This experimental treatment should be feasible in the clinical situation since only a short treatment time was required and delivery of the MCPM gel to specific sites was relatively easy.