Análise in vitro da cariogenicidade de sorotipos de Streptococcus mutans em biofilme monoespécie e associado à Candida albicans

Abstract

The existence of genes that express collagen-binding proteins (CBP's) in some serotypes of Streptococcus mutans, as well as their relationship with the presence of Candida albicans in dentin caries, may result in more severe patterns of caries progression on the dental substrate. Therefore, the objective of this study was to evaluate in vitro dentin caries lesions and the characteristics of the biofilm formed using different serotypes of S. mutans that present (+) or not (-) CBP genes (UA159: serotype c(-) , NN2002: serotype e (-), OMZ175: serotype f (+), YT1: serotype k (+) and FT1: serotype k(-), in mono and duospecies biofilm with C. albicans (ATCC 40119). In chapter 1, the formation of mono biofilm was carried out in biological triplicates, cultivated for 3 and 5 days on blocks of human dentin in the well (n=12). In chapter 2, the duo biofilm was cultivated in biological triplicates, for 3 days, on bovine dentin blocks covered with simulated acquired pellicle, being cultivated in two ways: in the bottom of a well (n=9) and suspended in metallic devices (n=9). For this, 24-well plates with culture medium were used (TSB/yeast extract/sucrose) incubated under microaerophilic conditions with 5% CO² at 37° C. The monospecies biofilms were evaluated for soluble extracellular polysaccharides (PEC-S) and biomass quantification. In the blocks, the depth and characteristics of the caries lesions formed through longitudinal microhardness (ΔS) and scanning electron microscopy (SEM) were evaluated. The duospecies biofilms were evaluated for CFU/mL count and total dry weight. In both experiments (mono and duo), the scaffold of biofilms formed after 3 days in the well was evaluated by confocal microscopy. Parametric data were submitted to ANOVA statistical analysis, followed by the Tukey and Bonferroni test; and non-parametric data by Fisher's chi-square test using the statistical software GraphPad Prisma® and significance level of (p<0,005). This study suggests that the different serotypes evaluated have cariogenic potential to cause caries lesions in dentin in mono and duospecies biofilms, however the CBP+ serotypes (f and k+) did not cause more severe lesions or denser biofilms when compared to the CPB- serotypes (c, e and k-) on the dentin substrate.