Hydroxyapatite is an important mineral component of tooth enamel, bioactive and tissue-compatible materials. Nano-hydroxyapatite is more similar to enamel apatite crystals, in this respect Nano-hydroxyapatite seems to have the potential to remineralize decay lesions. In terms of restorative and preventive dentistry, nano-hydroxyapatite has significant remineralizing effects on initial enamel lesions, certainly superior to conventional fluoride, and good results on the sensitivity of the teeth. The nano-hydroxyapatite has also been used as an additive material, in order to improve already existing and widely used dental materials, in the restorative field (experimental addition to conventional glass ionomer cements, which has led to significant improvements in their mechanical properties). This study was performed due to the role of nanohydroxyapatite in remineralization of enamel lesions and due to the fact that this role has not been studied in the in-situ study. The aim of this study was to investigate the effect of nano-hydroxyapatite on tooth remineralization following its demineralization with beer in Russia.