Impact of different fluoride varnish formulations on enamel demineralization prevention

Method: Enamel specimens were distributed into five groups (n=20), and treated with: Group-1: Duraphat (D), Group-2: Vanish (V; contains tri-calcium phosphate), Group-3: EnamelPro (EP; releases more fluoride in vitro and contains amorphous calcium phosphate), Group-4: fluoride-free placebo varnish (P), Group-5:  no varnish (negative control; NC).  After 6h in a pH cycling caries model, varnishes were removed, and specimens were placed in a remineralization solution for 18h, followed by 6 days of pH cycling conditions.  Specimens were analyzed for % Surface Microhardness Loss (%SMHL) and loosely-bound fluoride content.  Then, sectioned and analyzed for mineral content (using cross-sectional microhardness-CSMH) and lesion size (using confocal microscopy-CLSM).  Data were analyzed using ANOVA models.  

Result: %SMHL and CLSM results consistently showed that all FVs significantly (p<0.05) prevent demineralization at the surface and subsurface of the specimens.  Most of the prevention occurs under or next to the varnish, and it is mostly lost at 1000 mm from the varnish (and CSMH clearly showed a numerical trend similar to the other methods).  FVs with additional calcium compounds or releasing more fluoride in vitro did not show additional preventive effects.  In fact, V was inferior to the other two FVs on %SMHL. All FV treated groups presented significantly higher levels of loosely-bound fluoride than the controls, with D showing the highest level.

Conclusion: 5%NaF varnishes with different formulations prevent demineralization, but mostly under the area being applied or at close proximity.  FVs with additional calcium did not show additional preventive properties.