Below what pH does an acid attack occur?

An acid attack on teeth, which can lead to demineralization of enamel and eventually contribute to the development of dental caries, typically occurs when the pH level in the oral environment drops below 5.5. At this pH, hydroxyapatite, the primary mineral component of tooth enamel, begins to dissolve, making enamel more susceptible to decay.

Choosing a pH of 5.5 as the threshold for an acid attack is supported by dental research and clinical findings that show this is the critical level at which demineralization surpasses the natural remineralization processes supported by saliva. Values below this pH indicate a more acidic environment where the likelihood of enamel demineralization increases significantly, thereby putting the teeth at greater risk for caries and other forms of decay. The other options provided, while indicative of varying levels of acidity, do not represent the threshold at which demineralization actively occurs.