OBJECTIVETo evaluate the in vitro cario-static effect of Galla chinesis with biofilm model.

METHODSA four-organism bacterial consortium was cultured in a biofilm model on hydroxyapatite (HA) discs in a continuous culture system and exposed to repeated solution pulsing. There were three groups with different solution pulsed in the model: negative control group was pulsed with distilled water, positive control group was pulsed with 100 mmol/L sucrose solution and experimental group was pulsed with 100 mmol/L sucrose solution containing 4.0 g/L Galla chinensis. During the experiment, the dynamic changes of pH were recorded. After 6 pulses, surface structure of the biofilm was observed with a scanning electron microscope and the population on the biofilm was enumerated.

RESULTSGalla chinesis significantly inhibited the adherence of Actinomyces naelundii to HA disc compared with the control group and facilitated the removal of acid products. It was also found that the extra-cellular polysaccharide was reduced with the pulsing of Galla chinesis.

CONCLUSIONGalla chinesis in the biofilm model can partially reduce the cario-genic response of sucrose solution.