In situ remineralizing effect of fluoride varnish containing sodium trimetaphosphate

Objectives: Considering the limitations of in vitro protocols and the uncertainty surrounding the mechanisms of action of TMP, the present study evaluated the effects of a fluoride (F) varnish supplemented with TMP on the remineralization of caries-like lesions in situ.

Methods: Bovine enamel discs were selected by surface hardness after induction of caries-like lesions, and divided into 3 groups: Placebo (no F or TMP), 5% NaF and 5% NaF/5% TMP. Twelve subjects used palatal devices with four demineralized enamel discs for 3 days, after varnish application, following a double-blind, crossover protocol. Two blocks were removed 6 h after varnish application for analysis of loosely (CaF₂) and firmly bound F. In the remaining discs, the percentage of surface hardness recovery (%SHR), cross-sectional hardness (ΔKHN) and CaF₂ and F were determined after completion of the in situphase. Also, differential hardness profiles were calculated by subtracting the hardness values of the placebo group from those of the F groups at each depth. Data were subjected to ANOVA and Student-Newman-Keuls’ test (p<0.05).

Results: The 5% NaF/5% TMP varnish promoted significantly higher %SHR and lower ΔKHN when compared to the other groups, followed by 5% NaF and Placebo (p<0.05). A more pronounced effect of TMP on enamel remineralization (around 60%) was seen at deeper regions of the lesion when compared to the external part of the subsurface lesion (9%). Higher concentrations of CaF₂and F were observed for 5%NaF, followed by 5% NaF/5% TMP and Placebo (p<0.05).

Conclusion: The addition of TMP to a fluoridated varnish leads to enhanced remineralization of artificial caries lesions in situ and that its effects are more pronounced in depth when compared to a conventional formulation.