Potencial cariogênico do biofilme originado de inóculos de origem salivar e da placa dental de indivíduos livres de cárie e com lesões ativas de cárie

Abstract

In vitro microcosm’s biofilm models originated from salivary or plaque inoculum demonstrated that the type of inoculum leads to different microcosms, which could influence the cariogenic potential of in vitro biofilms. Thus, the aim of this study was to investigated the cariogenic potential of biofilms originating from different types of inoculum (saliva and dental plaque) from individuals with active caries and caries-free, in a microcosm biofilm model. Ten volunteers were selected from each caries condition (caries-free and caries-active) for paired collecting of saliva and dental plaque. Biofilm microcosms were originated from the inoculum on enamel specimens arranged individually in 24-well plates. Biofilms grown in defined medium enriched with mucin (DMM), and were subjected to cariogenic challenge (DMM supplemented with sucrose at 1%) for 6h/day. After 10 days, the biofilms were collected for analysis of outcome variables: mineral loss (percentage of surface hardness change) and microbiological composition of biofilms (count of CFUs - Colony Forming Units). Statistical analysis was performed using t-test, Linear Multivariate Analysis Model and Pearson's correlation coefficient. The comparative analysis between microbiological baseline data for types of inoculum (saliva and dental plaque) was not significantly different for individuals free of caries, and for caries-active was statistically significant only for mutans streptococci. Comparison between individuals with different caries conditions, was statistically significant for mutans streptococci and acid-tolerant microorganisms in dental plaque samples, and acid-tolerant in saliva. After 10 days of growth of biofilms under cariogenic challenge, the values for total microorganisms, lactobacilli, streptococci mutans, acid-tolerant; and also to the surface hardness change (% SHC), were not statistically significant, considering the type of inoculum and the caries condition. Positive correlation was found for % SHC and CFUs counts of acid-tolerant bacteria (r=0.406) and lactobacilli (r=0.379). Under the limits of this study, the cariogenic potential of biofilms, formed under identical conditions in vitro on this microcosm biofilm model is similar, regardless of initial differences found between the source and type of inoculum.