The Inhibitory Effect Of Gallnut Water Extract On The Formation Of Plaque Biofilms In Vitro

Dental plaque is the community of microorganisms found on a tooth surface as a biofilm, embedded in a matrix of polymers of host and bacterial origin. Plaque forms in an ordered way and has a diverse microbial composition that, in health, remains relatively stable over time (microbial homeostasis). The structure of the plaque biofilm might restrict the penetration of antimicrobial agents, while bacteria growing on a surface grow slowly and display a novel phenotype, one consequence of which is a reduced sensitivity to inhibitors. Therefore plaque is natural and contributes (like the resident microflora of all other sites in the body) to the normal development of the physiology and defenses of the hostThe predominant species from diseased sites are different from those found in healthy sites, although the putative pathogens can often be detected in low numbers at normal sites. In dental caries, there is a shift toward community dominance by acidogenic and acid-tolerating species such as mutans streptococci and lactobacilli, although other species with relevant traits may be involved. Strategies to control caries could include inhibition of biofilm development (e.g. prevention of attachment of cariogenic bacteria, manipulation of cell signaling mechanisms, delivery of effective antimicrobials, etc.), or enhancement of the host defenses. Prevention of dental caries with naturally occurring drugs has been the key point during last decades.In the previous study, Galla Chinensis had significant anti-caries effects in vitro and in artificial mouth model. This research simulated oral environment with artificial mouth equipment in vitro to observe how the water extract of Gallnut water extract inhibits bacteria plaque biomembran at differrent density and different time ,and the effect of structure, appearance, activity, composition of bacteria plaque biofilm.1 The influence of extracts of Chinese gallnut water on the morphology and bacterial number in the early formation process of plaque biofilm.In this experiment , the double dilution were used to evaluate the MIC values of streptococcus mutans, Streptococcus sanguis and actinomyces visosus . The compound Plaque biofilm were formed by these three kinds of bacteria in the artificial mouth,.and during the biofilm, extracts of Chinese gallnut water with four different concentration gradients(2.0,1.0, 0.5,0.25 mg/ml)below MIC value were applied. After 3 day's culture, bacterial colony count and morphology of plaque showed that extracts of Chinese gallnut water at the concentration of 2mg/ml,1mg/ml and 0.5mg/ml had the inhibitory effect on plaque biofilm formation ,which demostrated a dose dependent effect; and the inhibitory effect was not significant in terms of 0.25mg/ml ,which was similar with the effect of 0.5mg/ml concentration. From SEM observation, with the decrease of concentration of extracts of Chinese gallnut water , the plaque biofilm on the surface of HA showed a morphological change from sporadic distribution to regular reticular formation.And there was no difference between 0.25mg/ml group and the control one . Therefore, it was speculated that only extracts of Chinese gallnut water at the concentration of above 0.5mg/ml could take the relatively obvious inhibitory effect on the early formation of plaque biofilm.2 The influence of extracts of Chinese gallnut water on the structure and bacterial vitality in the early formation process of plaque biofilm.The compound plaque biofilm were formed by three kinds of bacteria in the artificial mouth,and extracts of Chinese gallnut water at a concentration of 2mg/ml were applied to interfere. After 3 day's culture, the morphology ,thickness of plaque biofilm and the number of dead/vital bacteria were investigated by specific fluorescence labelling and CLSM, then the percentage of vital bacteria was determined. The results showed that in the plaque biofilm, all the conduits structure was unclear , and the bacteria formed simple nodular structure, and the total number of bacteria as well as percentage of vital one were decreased . It was concluded that extracts of Chinese gallnut water could change the integrity of plaque biofilm's early structure and reduce the vitality of biofilm .Anti-dental caries by naturally occurring drugs is one of the focuses of caries prevention. Our previous study found that Chinese gall had a potent effect against caries which was further confirmed by the experiments on biofilm model in vitro. In present study, we used the artificial mouth to mimic the formation of plaque biofilm and investigated the effects of different concentration of extracts of Chinese gallnut water on the morphology ,structure and vitality of plaque biofilm, in order to provide basic experimental knowledge for the further studies on the mechanism of anti-caries of this Chinese natural drug.3. The effects of Chinese Gallnut water extract on the surface morphology during the formation of the plaque biofilm The experiment used the artificial mouth to simulate the process of Plaque Biofilm forming.After reated with 2mg/ml Chinese Gallnut water to the Plaque Biofilm on HA(Hydroxyl apatite) surface ,the surface morphological was measured on 6h,24h,48h,72h,7d by SEM. The results showed that the morphological of Plaque Biofilm have changed in the period of measurement:induded cell matrix reducing, the stereochemical structure of the biological membrane was not found,only observed the simple conglomeration or lamellar structure. The conclusion demonstrated that Chinese Gallnut water on the form of the Plaque Biofilm.4 Experiment Four: The effects of Chinese Gallnut water on quantity and composition of bacteria during the form of the plaque biofilm.The experiment used the artificial mouth to simulate the process of the forming of Plaque Biofilm. Using the selecting technology of culturing bacterium, the total bacteria count and various kind count were divided recorded; computed constituent ratio. Comparing to control group , the total count and 3 divided bacteria count were reducing in the period of the Plaque Biofilm forming after the treated with 2mg/ml Chinensis Gallnut water(P<0.05).Comparing to the control group, the constituent of Streptococcus mutans and Actinomyces viscosus were degraded; but the constituent of Streptococcus sanguis were heightened. The resulet indiated that Gallnut water extract may change the constituent of various kind bacteria and prevent the Plaque Biofilm from dental.