What is cariogenic plaque

Extracellular polysaccharides play a central role

BASEL (Biermann) - Theoretically, cariogenic bacteria create a hostile environment for themselves by leaching calcium from the tooth enamel and the resulting increased local calcium concentration. Researchers from the Clinic for Preventive Dentistry and Oral Microbiology and the Department of Biomedical Engineering at the University of Basel now describe in “Plos One” how the bacteria manage to survive anyway.

Their hypothesis: extracellular polysaccharides, EPS for short, support the survivability of bacteria. These are substances that cariogenic bacteria form from sugar residues and build up outside their cells. They form the scaffolding of the biofilm and ensure that bacteria can anchor themselves in the dental plaque.

The scientists have now been able to demonstrate that the cariogenic bacteria develop mechanisms that help them withstand the high calcium concentration. It has been shown that EPS have a large number of calcium binding sites with which they incorporate the leached calcium into the biofilm. This neutralizes the toxic content and strengthens the EPS structure of the biofilm.

The binding of calcium by the EPS not only helps the cariogenic bacteria in the tooth enamel to survive, it also leads to the development of tooth decay. “By binding calcium, EPS inhibits the remineralization of tooth enamel, because the plaque no longer contains enough free calcium. This discovery is important in order to be able to better understand calcium regulation in tooth decay, ”explains microbiologist Monika Astašov-Frauenhoffer.

Publication: Monika Astašov-Frauenhoffer, Muth M. Varenganayil, Alan W. Decho, Tuomas Waltimo, Olivier Braissant. Exopolysaccharides regulate calcium flow in cariogenic biofilms PLOS ONE (2017)

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Source: University of Basel, November 2nd, 2017

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