Effects of Rinses with an Acidic Calcium Phosphate Solution on Fluoride Uptake, Caries, and in situ Plaque pH in Rats

Abstract

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.

In vitro Remineralization of Caries Lesions Treated with Surface-Active Phosphates

“…They are caused by the fluctuations of plaque pH. Minerals (mainly fluoride-containing ap atites) are formed which are less soluble than the min eral originally present [Chow et al, 1981;Driessens, 1986;Schreiber et al, 1988]. The fundamental differ ences in the mode of action of fluoride and the amphi philic phosphates investigated in this study justify the expectation that these phosphates may add an extra caries-inhibiting effect to that of fluoride when ap plied simultaneously with fluoride.…”

Effects of an Acidic Calcium Phosphate Solution and the Intraoral Fluoride-Releasing Device on Dental Caries and Fluoride Uptake in Rats

“…In the first study the incidence of dental caries was substantially less than that noted previously [Shern et al, 1984a[Shern et al, , 1987Schreiber et al, 1988). Presumably, the reduced incidence resulted because the cariogenic challenge was postponed until after the treatment pe riod, thus allowing the natural resistance of the rats' teeth to increase.…”

“…Presumably, the reduced incidence resulted because the cariogenic challenge was postponed until after the treatment pe riod, thus allowing the natural resistance of the rats' teeth to increase. This reduced susceptibility and re sultant lower range of caries scores probably contrib uted to the insignificant negative correlation between the caries score and the level of enamel-bound fluo ride, i.e., r = -0.20, compared with r = -0.49 and r = -0.65, noted previously [Shern et al, 1987;Schreiber et al, 1988].…”

“…Also, enamel-derived fluoride may have de creased the duration of the pH restriction without in fluencing the initial pH decrease. The postmortem method for evaluating the pH of dental plaque was selected for its feasibility, reliability [Shern et al, 1984b] and expected response to various sugars [Shern et al, 1984b;Schreiber et al, 1988]. However, the characteristics of the pH method should be considered when interpreting the pH data.…”

“…The CPS creates a surface rich in dicalcium phosphate di hydrate that binds readily with fluoride to form a fluoridc-rich apatite. CPS and fluoride solutions applied sequentially produced high levels of fluorapatite with no morphologic change in the tooth surface in vitro [Chow and Brown, 1975], in rats [Shern et al, 1979[Shern et al, , 1984a[Shern et al, , 1987Schreiber et al, 1988] and in humans [Chow et al, 1981].…”