Aim. To compare the contents of potassium salts in specialized toothpastes, and to estimate the possibility for potassium ions diffusion through dentinal tubules after firm tooth tissues conditioning by a toothpaste containing fluoride. Methods. Toothpastes specially formulated to treat the pain of sensitive teeth: «Sensodyne F» (contains potassium chloride); «PresiDENT Sensitive» (potassium nitrate); «Asepta Sensitive» (potassium citrate) and new gel reducing dental sensitivity (contains potassium chloride) were examined. Speed of potassium ions diffusion through dentinal tubules after firm tooth tissues conditioning by a toothpaste containing fluoric substances were measures by potentiometry and a special device using tooth slice as a membrane. Results. Considering that toothpaste is applied within 5 minutes, while gel - within 15-20 minutes, it is possible to assume that potassium ions bioavailability from 1 g of gel can be assessed as 41 mg, compared to 5.9±0.5 mg from 1 g of paste №1, 0.4±0.05 mg - №2; 7.8±0.5 mg - №3. So, potassium ions bioavailability from 1 g of gel is 7; 102; 5 times higher (respectively) compared to toothpastes. Speed of potassium ions diffusion through dentinal tubules ranged between 0.2 to 1.64 μg/min and depended on the number of membrane potassium channels permeable for potassium. Fluoride toothpastes specially formulated to treat the pain of sensitive teeth reduced the speed of potassium ions diffusion from the solution by 4-7 times by blocking the dentinal tubules. This can be also associated with fluoride-containing protective film formation. Therefore, at the first stage of treatment of teeth hypersensitivity using new gel, it is better to use a toothpaste without fluoride. Conclusion. Compared to the examined toothpastes, new gel for reducing dental sensitivity contains higher number of potassium free ions, which can enter dentinal tubules reducing the effect on free nerve endings. Potassium ions diffusion through dentinal tubules reduced 4-7-fold after conditioning by a toothpaste containing fluoride.