What leads to enamel demineralization after being produced by oral bacteria and persisting for 20 to 40 minutes after sugar ingestion?

• A. Saliva enzymes
• B. Oral acids
• C. Protective minerals
• D. Neutralizing bacteria

Answer: (B)

When fermentable sugars are consumed, bacteria in dental plaque rapidly metabolize them and produce acids such as lactic acid. These acids lower the pH in the plaque to below the enamel’s critical level (about 5.5). At this more acidic environment, hydroxyapatite in the enamel begins to dissolve, releasing calcium and phosphate and causing demineralization.

The 20 to 40 minute window after sugar exposure represents the acid attack period during which the plaque remains acidic because the bacteria keep producing acid and saliva takes time to neutralize the environment. Once the pH rises again, remineralization can begin, especially with available minerals in saliva and fluoride in the mouth.

Other options don’t fit because saliva enzymes don’t cause demineralization; protective minerals promote remineralization rather than demineralization; and “neutralizing bacteria” isn’t a mechanism that explains enamel dissolution.