Studying on cariostatic effect of Galla Chinensis in biofilm model

Objective: Our previous studies have reported that some Traditional Chinese Medicine, especially Galla Chinensis (GC), have significant cariostatic effect in vitro. However, no study has been conducted to determine the effect of GC on a mixed culture of oral microflora. This study aimed to investigate the effects of GC on biofilm formation in vitro and to elucidate potential anticaries mechanisms. Methods: A four-organism bacterial consortium biofilm-enamel model was set up and pulsed with GC twice daily, 1 h prior to pulsing of sucrose (final concentration 10mM). Treatments were 4.0mg/ml GC with 100mmol/L sucrose, 100mmol/L sucrose and distill water. During the experiment, the pH dynamic change of the planktonic phase was measured continuously and the biofilm viable bacteria counting were enumerated. Enamel blocks underlying biofilm (n=4/treatment) were analyzed by polarizes light microscopy and the microstructure of biofilm was observed with SEM. Results: GC significantly inhibited adherence of Actinomyces naelundii except S.mutans, S.sanguis and S.salivarius in biofilm (p<0.05,t test). The extra-cellular polysaccharide was reduced with the pulsing of GC. No obvious inhibit effect was observed on acid production. Biofilm-induced demineralization of enamel blocks decreased significantly, and a consecutive and thicker mineralizable strip was observed in GC group. Conclusion: GC can partially reduce the cariogenic response of sucrose solution in the biofilm model, thus highlighting GC as a potential anticaries agent. Support for this investigation was provided from UNILEVER Research Port Sunlight.