In situ effect of fluoride toothpaste supplemented with nano-sized sodium trimetaphosphate on enamel demineralization prevention and biofilm composition

Objective: To evaluate the effect of a fluoride toothpaste containing nano-sized sodium trimetaphosphate (TMPnano) on enamel demineralization in situ and composition of the biofilm. Design: This crossover double-blind study consisted of four phases (seven days each) and 12 volunteers who wore oral appliances containing four enamel bovine blocks. The cariogenic challenge was performed by 30% sucrose solution (6x/day). The toothpaste treatments (3x/day) were as follows: no F/TMP/TMPnano (Placebo), 1100 ppm F (1100F), 1100F plus 3% micrometric or nano-sized TMP (1100F/TMP; 1100F/TMPnano). Percentage of surface hardness loss (%SH), and integrated loss of subsurface hardness (Delta KHN), as well as enamel calcium (Ca), phosphorus (P), and fluoride (F) were determined. Moreover, biofilm formed on the blocks were analyzed for F, Ca, P, and insoluble extracellular polysaccharide (EPS) concentrations. Data were analyzed using one-way ANOVA, repeated measures followed by Fisher LSD test (p < 0.001). Results: 1100F/TMPnano promoted the lowest %SH and Delta KHN among all groups (p < 0.001). Regarding the F concentrations in the enamel and in the biofilm, there were no significant differences between 1100 F and 1100 F/TMPnano, but significantly increased enamel Ca concentrations (p < 0.001). 1100F/TMPnano showed lower values of EPS concentration when compared with 1100F (similar to 80%) (p < 0.001). Conclusion: 1100F/TMPnano promoted a greater protective effect against enamel demineralization and significantly affected the composition of biofilm formed in situ when compared to 1100F toothpaste.