[The effects of tea polyphenols on the adherence of cariogenic bacterium to the salivary acquired pellicle in vitro].

OBJECTIVE

It has been proved that tea polyphenols (TP) can inhibit the sucrose-dependent adherence of oral cariogenic bacterium to the tooth surface. This study is carried on to investigate the effects of tea polyphenols on the preliminary adherence of main cariogenic bacterium to salivary acquired pellicle and reveal the anticarious mechanisms of tea polyphenols further.

METHODS

The hydroxyapatites were coated by saliva to form S-HA, an in-vitro model of experimental pellicle. Streptococcus mutans 3a3 and Actinomyces viscosus ATCC 19246 were chosen as the main cariogenic bacterium, and the microorganisms were radiolabelled by growing them in TPY culture medium supplemented with 3H-thymidine. Tea polyphenols solution was prepared, the concentrations of which were 0.5, 1.0, 2.0 and 4.0 mg/ml respectively. Two parts of inhibited adherence tests were done with TP-treated S-HA or TP-treated bacterium. In the first one, S-HA was immerged into the TP solution of different concentrations for 1 h before the attachment of bacterium. In the other, the bacterium were mixed with the TP solution for 1 h and then centrifuged and washed before bound to S-HA. The whole process was carried on in KCl buffer solution. The number of 3H-thymidine-labelled bacterium which attached to S-HA were determined by scintillation counting.

RESULTS

In both the two parts of this study, tea polyphenols solution, the concentrations of which were changed from 1.0 to 4.0 mg/ml, could decrease the number of S. mutans 3a3 and A. viscosus ATCC 19246, and the inhibition rates rose with the increase of the concentrations of TP solution. But the inhibitory effects of 0.5 mg/ml TP solution were inconsistent in different tests. The results showed that 1.0-4.0 mg/ml TP solution could inhibit the attachments of S. mutans and A. viscosus to S-HA effectively. The inhibitory functions of tea polyphenols were so obvious that in some experiments, while the concentrations of TP solution were changed from 2.0 to 4.0 mg/ml, the number of 3H-thymidine-labelled bacterium which attached to S-HA was even less than that of the same bacterium which attached to naked HA.

CONCLUSION

Tea polyphenols can inhibit the preliminary adherence of Streptococcus mutans and Actinomyces viscosus to S-HA effectively. TP may prevent enamel from caries by decreasing the adherence of main cariogenic bacterium to salivary acquired pellicle.