An In vitro study of nanohydroxyapatite-fortified toothpaste on tooth remineralization: microhardness, mineral content, and biocompatibility

Nanohydroxyapatite (nano HA) has gained broad interest not only in orthopedy but also in dentistry. In dentistry, nano HA has been developed as a biomimetic agent for oral care due to the similar chemical composition and particle size with hydroxyapatite crystals of enamel and dentin matrix. Being explored as a biomimetic agent, nano HA has been developed for remineralization and, thus, protection of early dental erosion. This study aimed to evaluate the effect of toothpaste containing nano HA on remineralization and their biocompatibility for personal oral care. The remineralization was evaluated by surface microhardness and mineral content changes in extracted human premolar teeth following toothpaste application. The biocompatibility of toothpaste was evaluated through lactate dehydrogenase (LDH) activity and interleukin-1alpha assay using HEK293T cells. The microhardness of specimens increased for all toothpaste formulas indicating the effectiveness of remineralizing dental caries. The linear correlation of elemental percentage changes indicates the ability to improve both teeth’s calcium and phosphor content. Moreover, the LDH assay showed that most toothpaste formulas exhibit a low degree of cytotoxicity considerably as a safe oral product. The inflammation study (interleukin-1alpha determination) showed no acute irritation in most formulas with the same score of negative control (untreated with toothpaste).