Characterization and effect of nanocomplexed fluoride solutions on the inhibition of enamel demineralization created by a multispecies cariogenic biofilm model

Objectives: The aim of this study was to assess the in vitro caries preventive effect of nanocomplexed solutions of hydroxypropyl-β-cyclodextrin and γ-cyclodextrin associated with titanium tetrafluoride (TiF₄) after different complexation times (12 or 72 h).

Materials and methods: Enamel blocks were randomly distributed in 9 groups (n = 11): negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, TiF₄, hydroxypropyl-β-cyclodextrin:TiF₄ 12 h, hydroxypropyl-β-cyclodextrin:TiF₄ 72 h, γ-cyclodextrin:TiF₄ 12 h, γ-cyclodextrin:TiF₄ 72 h, and NaF (positive control). The solutions were applied for 1 min and the blocks were exposed to a biofilm model. Nanocompounds were characterized by differential scanning calorimetry and X-ray powder diffraction. The percentage of surface microhardness loss (%SML), mineral density changes (ΔZ), lesion depth, surface morphology (scanning electron microscopy-SEM), and chemical characterization (energy-dispersive spectroscopy-EDS) were assessed.

Results: No oxidation was observed, and the formation of the nanocomplexes was evidenced by changes in the melting point compared to pure cyclodextrins and the loss of crystallinity of the materials. Hydroxypropyl-β-cyclodextrin:TiF₄ 72 h resulted in lower %SML than negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, and TiF₄ (p < 0.05). NaF differed from all groups (p < 0.05), except for hydroxypropyl-β-cyclodextrin:TiF₄ 72 h (p = 0.83). ΔZ of hydroxypropyl-β-cyclodextrin:TiF₄ 72 h was higher than negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, γ-cyclodextrin:TiF₄ 1 2 h, γ-cyclodextrin:TiF₄ 72 h, and NaF (p < 0.05) and similar to TiF₄ and hydroxypropyl-β-cyclodextrin:TiF₄ 12 h (p > 0.05). SEM/EDS detected Ti in the blocks subjected to TiF₄-products.

Conclusion: The hydroxypropyl-β-cyclodextrin:TiF₄ 72 h solution showed caries preventive effect on the surface and subsurface of the enamel.

Clinical relevance: A hydroxypropyl-β-cyclodextrin nanosystem, in association with TiF₄ after 72 h of complexation, may be a promising agent for the prevention of enamel demineralization.