Low fluoride dentifrice associated to the nano-sized TMP: An In vitro study

Objectives: The aim of this in vitro study was to evaluate the effect of low fluoride dentifrices (250 ppm F) containing nano-sized sodium trimetaphosphate (TMPnano) on the demineralization of bovine enamel.
Methods: Blocks of bovine enamel (n=144) were randomly divided into 12 experimental groups of dentifrices (pH 7.0): Placebo (no F or TMP), 1,100 ppm F (conventional dentifrice), 250 ppm F (250), 250 ppm F plus micrometric TMP (250-TMP) or nano-sized TMP milled for 24h (250-TMPnano24) or 48h (250-TMPnano48). Micrometric and nano-sized TMP were added to the formulations at concentrations of 0.05%, 0.1% and 0.25%. Blocks were subjected to pH-cycling regimen for five days, where the treatment was performed with the suspensions of dentifrices 2x/day. To evaluate mineral loss, surface hardness (SH) and the percentage of surface hardness loss (%SH) were analyzed. Fluoride (F), calcium (Ca), phosphorus (P) and Ca/P molar ratio in enamel were also determined. Data were submitted to Kruskal-Wallis test, followed by Student-Newman-Keuls’ test (p<0.05).
Results: All concentrations of TMPnano significantly reduced %SH (p˂0.05). In addition, the dentifrices 250-TMPnano24 and 250-TMPnano48 led to higher F, Ca, P and Ca/P content in enamel only at 0.05% (p˂0.05); only the 250-0.05TMPnano48 did not show significant difference when compared with 1,100 in respect to Ca/P molar ratio in enamel (p˂0.05).
Conclusions: It was concluded that the anticaries effect of the 250 ppm F dentifrice containing 0.05% nano-sized TMP milled for 48h was greater than 250 ppm F and similar to the conventional dentifrice.