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Abstract
Objectives
The purpose of this study was to investigate changes in the composition of artificial cariogenic biofilms using a Streptococcus mutans biofilm model over a period of time.
Methods
We analyzed the dry weight, colony forming unit (CFU) number, extracellular polysaccharide (EPS) biovolume, and acid production rate of S. mutans biofilms formed on saliva-coated hydroxyapatite discs after 26 h, 50 h, 74 h, 98 h, 171 h, and 195 h. In addition, we performed a laser scanning confocal fluorescence microscopy to determine the bacterial volume, EPS biovolume, and biofilm thickness. We calculated the biofilm density using dry weight and EPS biovolume.
Results
Over a period of time, there was no change in the CFU number and acid production rate of S. mutans biofilms, but there was an increase in the dry weight and EPS biovolume of S. mutans biofilms. The bacterial volume, EPS biovolume, and biofilm thickness only increased in the 50-hold biofilm; however, no change was observed in 50-195-h-old biofilms. In addition, an increase in the biofilm density was observed over time.
Conclusions
These results suggest that the acid production ability of cariogenic biofilms does not change, but the biofilm density increases over time. However, due to scientific information, further research needs to be conducted in the field of dentistry to get further insights on the progression of cariogenic biofilms over time.
References
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Fig. 1.
S. mutans biofilm formation and experimental scheme for the present study. CFUs and CLSM represent colony forming units and confocal laser scanning microscope, respectively.
Fig. 2.
Change over time in dry weight of S. mutans biofilms. The data represent the mean±SD (n=8). Values followed by the same superscript are not significantly different from each other.
Fig. 3.
Change over time in CFUs (A) and extracelluar polysaccharides (EPS, B) of S. mutans biofilms. The numbers in parenthesis represent the percentage of water-insoluble and water-soluble polysaccharide out of dry weight. The data represent the mean±SD (n=8). Values followed by the same superscript are not significantly different from each other.
Fig. 4.
Changes over time in acidogenic ability of S. mutans biofilms. The data represent the mean±SD (n=8). Values followed by the same superscript are not significantly different from each other.
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