Which statement describes the interaction between diet and oral flora in caries development?

• A. Interaction between oral flora and dietary carbohydrates (sugars)
• B. Diet has no influence on caries
• C. Caries are caused by viruses
• D. Only oral hygiene matters

Answer: (A)

Caries develop when diet provides fermentable carbohydrates that fuel the acids produced by the plaque biofilm. When sugary or starchy foods are eaten frequently, the bacteria in dental plaque metabolize these carbohydrates into acids, which lower the local pH. If the pH in the plaque drops below about 5.5 for enamel, minerals start to dissolve out of the tooth—demineralization. Repeated cycles of acid attack and remineralization (with fluoride present) lead to progressive demineralization and eventually cavities. This interacts with the microbial ecology: sugar-rich environments favor acidogenic and aciduric bacteria, like mutans streptococci and lactobacilli, which amplifies the problem.

Other statements aren’t correct because caries aren’t caused by viruses, and while good oral hygiene helps, diet has a direct influence by shaping the biofilm's balance and acid production.