Microcosm Biofilms Originating from Children with Different Caries Experience Have Similar Cariogenicity under Successive Sucrose Challenges

Abstract

Objectives: The source of saliva inocula and the individual characteristics of saliva donors could affect the cariogenic activity of in vitro biofilms, but this could also be modulated by environmental determinants, such as the frequency of sugar consumption. Therefore, the aim of this study was to compare the cariogenicity of microcosm biofilm growths from the saliva of caries-free (CF) children, children with early childhood caries (ECC) and with severe ECC (S-ECC), under regular sucrose exposure. Methods: Microcosm plaque biofilms were initiated from the saliva of CF, ECC and S-ECC children. Biofilms were grown in 24-well microplates on bovine enamel discs for up to 10 days in artificial saliva, which was replaced daily. Growth conditions comprised cariogenic challenge (artificial saliva supplemented with 1% sucrose 6 h/day) or no cariogenic challenge. Daily pH was obtained from the artificial saliva, and after the experimental period, the biofilm formed on the enamel discs was collected for microbiological analyses. Mineral loss in enamel discs was estimated by percentage of surface hardness change. Results: Overall, no statistically significant differences were found among saliva sources (p > 0.05). Streptococcus mutans and lactobacilli counts increased in the biofilms grown under cariogenic challenge (p < 0.05), while a substantial decrease in the artificial saliva pH was detected under the same condition (p < 0.001). Higher demineralization (p < 0.001) was observed under sucrose exposure regardless of caries experience of children. Conclusions: While the sucrose exposure determined the cariogenicity of the biofilms, the caries experience of children who provided the inocula did not affect mineral loss associated with these biofilms.