Studies on the Relationship between Periodontopathic and Cariogenic Bacteria

Objective: The aim of this study was to investigate the growth、decline and coaggregation relationship between periodontopathic and cariogenic bacteria. Methods: The representative periodontopathic bacteria--Porphyromonas gingivalis(Pg ATCC 33277)、Actinobacillus actinomycetemcomitans (Aa FDC Y4)、 Provotella intermedium(Pi ATCC 25261)、Fusobacterium nucleatum(Fn ATCC 25586) and cariogenic bacteria-- Streptococcus mutans(Sm Ingbritt)、Streptococcus sanguis(Ss ATCC 10556)、Lactobacillus acidophilus(La ATCC 4356)、Actinomyces viscosus(Av ATCC 19246) were selected. The modified chemostat under analogous oral environment、 live bacterial Gram fluorescence staining and confocal laser scanning microscopy were used. The rule of bacterial growth or decline and coaggregation was investigated by means of comparing corresponding planktonic phase and the coaggregation relationship was investigated by both visual assay and turbimetric assay.Results: The findings showed that the bacterial colonization and coaggregation exhibited obvious genera and species specificity and had certain sequence and discipline. Gram positive cariogenic bacteria initially colonized, followed by the time-dependently increasing amounts and proportions of Gram negative periodontal pathogens distributing in Gram positive bacterial clusters or on the surface.The coaggregation degree among various periodontopathic and cariogenic bacteria are different.The degrees of coaggregating pairs,such as Fn-Av、Fn-Sm、Fn-Ss、Fn-La、Pg-Av and Pg-Ss are higher than +2 or 20%. The growth of periodontal pathogens(Pg,Aa,Fn)were significantly inhibited by La when they were cultured with La respectively( P<0.01 or P<0.001). Conclusions: It has been found that ecological relationship between periodontopathic and cariogenic bacteria had a main tendency of antagonism. The culture mixture of La and periodontopathic bacteria proved that La strongly inhibited the growth of Aa、Pg and Fn. La would be used as a beneficial strain of bacteria in periodontal ecological prevention which needs further study.Supported by grant 30070813 from National Natural Scientific Foundation.