Interaction of 2-, 3-, 4-carboxyethylpyridines (L1, L2, L3) with fluorosilicic acid results in the corresponding bis(pyridinium) hexafluorosilicates I–III, characterized by elemental analysis, IR, ¹H, ¹⁹F nuclear magnetic resonance (NMR), and mass spectrometry, solubility data, and X-ray crystallography. Crystallographic data: Fdd2, Z = 8, a = 28.610(2) Å, b = 18.8378(14) Å, c = 7.3236(5) Å (I); P-1, Z = 1, a = 6.2712(4) Å, b = 7.1706(5) Å, c = 10.9721(7) Å, α = 102.514(6)°, β = 97.037(5)°, γ = 93.640(6)° (II); P2₁/c, Z = 2, a = 10.0345(6) Å, b = 9.8734(5) Å, c = 9.4704(6) Å, β = 94.347(6)° (III). The dominant intermolecular contacts from the Hirshfeld surface analysis are H^…F/F^…H, H^…H, and H^…O/O^…H with percentages of 33.3%–34.5%, 26.4%–30.0%, and 16.0%–21.8%. The infrared spectra for I–III exhibit stretching vibrations ν(N⁺H) at 3300–3050 cm^–1; stretching and deformation vibrations ν(SiF) and δ(SiF₂) for [SiF₆]^2– anions are registered near 740 cm^–1 and in the range of 480–440 cm^–1. In the ¹⁹F NMR spectra of aqueous solutions of I–III, strong singlet signals of the [SiF₆]^2– anion were registered at δ(F) = −133.35 ppm (I), –131.43 ppm (II), –129.02 ppm (III) with two satellites due to the spin-spin interaction ²⁹Si–¹⁹F (J(²⁹Si–¹⁹F) = 107.5 Hz (II), 107.6 Hz (III)). I–III reveal high solubility in water and dimethyl sulfoxide and very poor solubility in methanol and ethanol. All compounds demonstrate noticeable anticaries activity and absence of hepatotoxic effects, and bis(3-carboxyethylpyridinium) hexafluorosilicate II displays the highest caries-preventive efficacy, which significantly exceeds values for the reference preparations, NaF and (NH₄)₂[SiF₆].