This study presents the results of an experimental use of pastes with hydroxyapatite and with nanohydroxyapatite to compare the effect of occlusion of dentinal tubules. When performing work we estimated the morphological changes of the dentin surface using scanning electron and atomic force microscopy. The detailed assessment of dentin structural features under significant amplification it was possible to identify differences in plugging dentin tubules by different kinds of pastes. It was found that the cut surface of dentin after the application of the pastes is covered with the unified layer of the paste's particles and their individual conglomerates.