What is the critical plaque pH that indicates potential dental caries?

The critical plaque pH that indicates potential dental caries is 5.5. This pH level is significant because it represents the threshold at which demineralization of the enamel begins to occur. When the pH of dental plaque drops to 5.5 or lower, the acidic environment facilitates the leaching of minerals, particularly calcium and phosphate, from the tooth structure, leading to the formation of carious lesions.

Maintaining a plaque pH above this critical level is essential for oral health. Regular oral hygiene practices and dietary habits can help keep the plaque pH above 5.5, thereby preventing the onset of dental caries. The other options represent pH levels that are either too acidic or too neutral for the onset of demineralization, which is why they do not serve as the critical threshold for caries development.