Which bacterium is the main cause of dental caries by producing acid from sugars in dental plaque?

Streptococcus mutans is a major bacterium involved in dental caries by producing acid from sugars in dental plaque.

S. mutans can attach to tooth surfaces and help build a sticky biofilm. When dietary carbohydrates are available, it ferments them into acids, lowering the pH around the tooth. Repeated acid attacks can dissolve mineral from enamel and contribute to cavities.

Dental caries is a biofilm-associated disease involving a community of microorganisms, so S. mutans is not the only microbe that can participate. Its acid production and ability to persist in acidic plaque nevertheless make it a particularly important research subject.

A common misunderstanding is that sugar directly “infects” a tooth. Instead, frequent fermentable-carbohydrate exposure feeds plaque microbes, while saliva, fluoride, brushing, and time influence whether mineral loss progresses. S. mutans is also distinct from streptococci that cause throat infections or pneumonia.