Streptococcus mutans and how xylitol combats it

You’re probably here because you want to know all about the bacteria Streptococcus mutans and how it affects your oral health.

Well, in learning these key facts about S. mutans, you’ll likely realise it’s a highly harmful bacteria and that xylitol helps to counteract its effects.

Streptococcus mutans: facts and effects

Let’s be absolutely clear about this: a high presence of Streptococcus mutans is behind all major oral health problems. Specifically, it’s:

• the main bacteria responsible for tooth decay, followed by Streptococcus sobrinus;
• the main bacteria responsible for enamel demineralisation;
• and one of the factors responsible for the formation of plaque.

Furthermore, it is acidogenic (it produces acids when metabolising food) and acid-tolerant (it can survive in the presence of acids).

That’s incredible! How can it be so harmful to oral health?

Why does it cause tooth decay and demineralise the enamel?

Put simply, this happens because when S mutans metabolises particles of food present in your mouth — its favourite being table sugar — it produces lactic acid. This causes the minerals in the enamel to react chemically with the acid to neutralise it. Consequently, the enamel and the tooth structure gradually weaken, to the point where cavities appear and the enamel demineralises.

It is true that there are other bacteria responsible for tooth decay — for example, Streptococcus sobrinus, Lactobacillus spp and
Actinomyces spp — and for enamel demineralisation — for example, Streptococcus sanguinis and, once again, Actinomyces spp—but S. mutans is the most aggressive in both cases.

Why does it play a role in the formation of plaque?

Dental plaque forms when proteins in the saliva coat the tooth. Bacteria attach themselves to this coating, producing sticky substances and creating an organised biofilm.

Streptococcus mutans contributes to plaque formation because it adheres strongly to the teeth (particularly in the presence of sucrose) and produces the sticky substances that become part of the biofilm.

How xylitol helps

The good news is that xylitol, when consumed regularly and in the right amount, inhibits the growth and activity of S. mutans and other harmful bacteria such as S. sobrinus, helping to prevent tooth decay and plaque and to stop the enamel from weakening. Xylitol has a greater effect on S. mutans than on other bacteria.

Furthermore, it stimulates the production of saliva, which is alkaline and acts as a natural cleaner for the mouth, counteracting the harmful effects of S. mutans.