The article presents the results of a study of water absorption and solubility properties of constructional polymers of hot and cold curing: «Ftoraks», «Acry-Free», «Castdon», «Nylon», «Perflex», made in accordance with the manufacturer’s instructions. It is possible to estimate the amount of nonvolatile substances washed out of the polymer, when using distilled water, by the solution density and optic density, measured in the wavelength range 220–254 nm. «Ftoraks» plastic samples made with different monomer content (in permissible range), are analyzed after their interaction with distilled water, 0,9 % sodium chloride, 0,9 % calcium chloride solution and model solution of saliva. Experimental data have shown that the separation of the monomer in the aqueous medium depends upon the medium composition and the ratio of components used for the preparation of the construction material. The separation of monomer from the polymer structure into solutions of salts is possible to evaluate by the glass transition temperature which characterizes thermomechanical properties of the polymer material.