Abstract: Abstract: Objective To test microhardness of artificial caries which was treated by different extracts of Geranium Strictipes R.Kunth,to observe its surface morphology by SEM,and to study the effects of different solvent extracts on remineralization of artificial demineralized enamel.Methods 5 groups of artificial demineralized enamel caries models were established by chemical methods:the group of ethyl acetate extract,the group of butanol extract,the group of water layer extract,20 mg/mL NaF positive control group,and deionized water negative control group.After in vitro pH cycling,microhardness was tested and the surface morphology was observed by SEM.Results Microhardness results showed that after the remineralization treatment by three different extracts and NaF,the enamel hardness in each group significantly increased than that before remineralization （P＜0.05）,while the deionized water group showed no significant remineralization difference （P>0.05）,and comparison between groups was statistically significant （P＜0.05）,denoting the remineralization effects of different extracts of Geranium Strictipes R.Kunth and NaF on demineralized bovine incisors.SEM results showed there was uniform and close precipitation zone in NaF group,loose surface structure in deionized water group,close mineral deposits and a small gap in the group of butanol extract,less mineral deposits and a larger gap in the group of ethyl acetate extract,and regular particle deposits in the group of water layer extract.Conclusions The different extracts of Geranium Strictipes R.Kunth have remineralization effects on artificial demineralized enamel.The best effect was obtained by water layer extract,then butanol extract,and lastly ethyl acetate extract.

Key words: Geranium Strictipes R.Kunth, enamel, remineralization, microhardness, SEM