Fluoride and calcium concentration in the biofilm fluid associated with fluoridated dentifrices supplemented with sodium trimetaphosphate or calcium glycerophosphate, under cariogenic challenge

Recent studies demonstrated that low fluoride dentifrices (LFD, 550 μg F/g) supplemented with calcium or phosphate have a similar effectiveness to a conventional dentifrice (CD, 1100 μg F/g). However, the mechanisms by which these compounds act on the de- and remineralization processes remain unclear. The present study evaluated fluoride (F) and calcium (Ca) concentrations in the biofilm fluid formed in situ under cariogenic challenge after using F dentifrices, supplemented or not with sodium trimetaphosphate (TMP) or calcium glycerophosphate (CaGP). Volunteers (n=12) were randomly divided into 5 groups according to the following toothpastes: Placebo (no F or CaGP, TMP), CD and LFD with no supplementation (550F) or supplemented with 1% TMP (550F-TMP) or 0.25% CaGP (550F-CaGP). In each phase, volunteers wore palatal appliances containing 4 bovine enamel blocks. The cariogenic challenge was produced using a 30% sucrose solution, 6 times a day. On the morning of the 8th day, biofilm samples were collected 1h and 12h after brushing and cariogenic challenge. F and Ca analyzes were performed with the inverted electrode after buffering with TISAB III and using the Arsenazo III method, respectively. Data were submitted to 2-way ANOVA (repeated measures) and Student-Newman-Keuls test (p<0.05). A dose-response relationship was verified between F concentrations in the dentifrices and those in the biofilm fluid. Significant differences were observed among Placebo, 550F and CD only 1 h after brushing, without statistical differences among 550F, 550F-TMP and 550F-CaGP. No defined trend was observed among the groups regarding Ca concentrations in the biofilm fluid, with the highest values found for Placebo and 500F-CaGP. It was concluded that the anticaries effects of LFDs supplemented with CaGP or TMP cannot be related to an increased availability of F and Ca in the biofilm fluid.