Abstract: Objective: To evaluate the remineralization effect of fluoride nano hydroxyapatite on early root caries and to compare the effect of remineralization between nano hydroxapatite, the fluoride foam, and the sodium fluoride. Methods: Forty-one artificial early root caries models were prepared, and the root surfaces were observed by scanning electron microscope (SEM). After demineralization, the micro hardness of the caries was measured, and the samples were randomly divided into 5 groups: the fluorine nano hydroxyapatite group, the nano hydroxyapatite group, the fluoride foam group, the sodium fluoride solution group, and the control group. The samples in each group were demineralized by pH circulation for 7 days, and were remineralized by different agents for 20 days. Finally, the samples were observed by SEM and the micro hardness was tested. Results: Large grains of crystals were deposited on the root surface in the fluoride nano hydroxyapatite group, and the surface of the group was smoother than those in the other groups. Micro hardness of the fluoride nano hydroxyapatite group was statistically different from those of other groups (P<0.05). Conclusion: The fluoride nano hydroxyapatite could improve the remineralization of the early root caries.

Key words: Fluoride nano hydroxyapatite , Early root caries , Remineralization, pH-cycling