Effect of calcium prerinse on the enhancement of fluoride mouthrinse on the inhibition of enamel demineralization

A calcium (Ca) pre-rinse has been recommended to enhance the anticaries effect of fluoride by increasing its retention in the oral cavity (saliva, dental biofilm) after the use of toothpastes or mouthrinses. Although this pre-rinse, followed by the use of fluoride rinse, has been associated with a significant increase in the fluoride concentration in saliva and dental biofilm, its anticaries effect has not yet been demonstrated experimentally. Thus, the objective of this study was to verify if a calcium pre-rinse potentiates the effect of fluoride on the reduction of enamel demineralization. In a double-blind, crossover, in situ study in 4 phases of 14 days each, ten volunteers wore a palatal appliance containing enamel slabs. Sucrose solution (20%) was dripped onto the slabs 8 times/day to simulate a high cariogenic challenge. Twice/day volunteers rinsed with: (1) A Ca placebo pre-rinse (sodium lactate) followed by a distilled water rinse (negative control); (2) A placebo pre-rinse followed by a 250 ppm F rinse; (3) A placebo pre-rinse followed by a 1000 ppm F rinse; or (4) A Ca pre-rinse (150 mM Ca as Ca lactate), followed by a 250 ppm F rinse. Response variables were: in the biofilm: F concentrations in the fluid and solid; in enamel slabs: percentage of surface hardness loss (%SHL), cross-sectional hardness and F concentration in enamel (loosely-bound and firmly-bound). The Ca+ F group resulted in similar mineral loss than the 1000 ppm F group (ANOVA, p>0.05), but both differed significantly from the other groups (p<0.05). The F concentration in the solids of the biofilm treated with Ca + F was ?22 times greater when compared to using only F (250 ppm F), being significantly higher than all other groups (p<0.05). However, in the biofilm fluid, the twice increase in F concentration caused by the Ca + F treatment when compared to the 250 ppm F group was not significant. The Ca pre-rinse did not increase F concentrations in the enamel. In conclusion, the Ca pre-rinse followed by an F rinse enhances the effect of F on the inhibition of enamel demineralization, which seems to be linked to its ability to increase the F concentration in the biofilm (AU)