The Dynamic Changes Of Virulence Factors And Cariogenic Bacteria In Plaque Biofilms With The Development Of Dental Caries

Dental caries is an important common oral diseases that seriously harms human beings' health. Dental plaque biofilms is the initiation factor of caries. We put forward continuous-flow plaque hypothesis based on our previous study which showed that caries susceptibility is not in accord with the detection rate or quantum of some recognized cariogenic bacteria, also supporting the ecological plaque hypothesis and the "core microbiome". Furthermore, the role of multi-cariogenic virulence factors and the cariogenic bacteria played in the development of dental caries need to be explored by this longitudinal study which can't be achieved on the clinical but by animal models.Objective:To observe the changes of gene expression of spaP, gtfB, Idh and F-ATPase on adhesion, glycometabolism, acid production and acid resistance of microbial organisms in dental plaque during the development of dental caries and discuss the viaritions of some cariogenic bacteria such as Streptococcus mutans, Streptococcus sobrinus, Streptococcus, Lactobacillus in biofilms at the beginning and the development of dental caries, combined with previous research results, we evaluate the relationship between the microbial biofilm and dental caries comprehensively and systematically, which may further provide the evidence for ecological plaque theory and the continuous flow hypothesis.Methods:18-day-old male Wistar rats were randomly divided into A,B,C and control groups (N=6). The rats of A,B and C were fed with caries 2000 and 5% glucose,separately; Control group fed with normal diet. Total RNA and DAN were collected from plaque samples which were collected from rats oral cavity once a week, and the gene expression of virulence factors and the amount of Streptococcus mutans, Streptococcus obrinus, Streptococcus oralis and Lactobacillus were detected by FQ-PCR.Results:①At the stage of caries initiation:the expression of spaP mRNA increased until the caries lesion appeared five weeks later. The expression of spaP of caries group was significantly higher than that of control group(P<0.05 or P<0.01); The expression of gtfB,ldh and F-ATPase was progressively increased during the caries development (P<0.05 or P<0.01).②Streptococcus mutans,Streptococcus oralis,Streptococcus sobrinus and Lactobacillus were detected in all samples;Streptococcus mutans and Streptococcus sobrinus increased constantly with the development of caries(P<0.05 or P<0.01).Conclusion:Adhesion virulence PAc of microflora in dental plaque may act on the initiation of dental caries, which play important roles continuously in the development of the whole process of dental caries on GTF adhesion, LDH acid production,and F-ATPase acid toxicity. Longitudinal study showed that both Streptococcus mutans and Streptococcus sobrinus are related to a positive correlation with the development and progression of dental caries in animal models.