Abstract: Objective To investigate the effect of tea polyphenols on early dental caries progression. Methods An early caries model of enamel and dentin of bovine teeth was established by extracorporeal demineralization. The samples of enamel caries and dentin caries were randomly divided into 4 groups (n=6): blank control group (DW group), sodium fluoride group (NaF group), tea polyphenol group (TP group) and tea polyphenols combined with sodium fluoride group (TP+NaF group). The pH circulation experiment was conducted to simulate the process of early caries. The concentrations of calcium and phosphate ions in the demineralization solution after pH cycle were detected, and the microhardness of tooth surface was detected by surface microhardness tester. X-ray energy spectrum was used to analyze calcium-phosphate ratio on tooth surface, and the hydroxyproline level in the remineralization solution was determined. Results There was no significant difference in the release of calcium and phosphate ions of the demineralization solution of enamel and dentin between TP group and the DW group, which was significantly higher than that of NaF group and TP+NaF group (P＜0.05). There was no significant difference in the microhardness of enamel surface between TP group and DW group, and the microhardness of dentin surface was higher than that of DW group. The microhardness of enamel and dentin surface was lower in DW group and TP group than that of NaF group and TP+NaF group (P＜0.05). Calcium-phosphate ratio of enamel and dentin surface was significantly higher in TP group than that in DW group (P＜0.05). There was no significant difference in the calcium-phosphate ratio of enamel surface between TP group, NaF group and TP+NaF group, while the calcium-phosphate ratio of dentin surface was significantly lower in TP group than that of the NaF group and TP+NaF group (P＜0.05). The levels of hydroxyproline in dentin remineralization solution were significantly lower in NaF group and TP+NaF group than those of DW group and TP group (P＜0.05). There were no significant difference between TP group and DW group, and TP+NaFgroup and NaF group. Conclusion During the early caries progression, tea polyphenols dose not significantly inhibit enamel and dentin demineralization, but could promote the redeposition of calcium and phosphate ions, which can effectively delay the development of dental caries.

Key words: dental caries, polyphenols, sodium fluoride, tea polyphenols, demineralization, remineralization