Australian Dental Council (ADC) Test 2026 – 400 Free Practice Questions to Pass the Exam

The critical plaque pH that can lead to dental caries is established at 5.5. This is a significant threshold because when the plaque pH falls below this level, demineralization of tooth enamel begins to occur. Enamel, composed primarily of hydroxyapatite, is vulnerable to acid produced by bacteria in dental plaque, particularly when fermentable carbohydrates are present.

At a pH of 5.5, the solubility of hydroxyapatite increases, leading to the loss of minerals from the enamel, which can ultimately result in the development of cavities if the acid exposure is prolonged. Maintaining a plaque pH above this critical level is crucial for oral health, as it supports remineralization processes that can counteract early demineralization.

Understanding this pH threshold is vital for both preventive measures against caries and for guiding treatment strategies in dentistry, emphasizing the importance of diet and oral hygiene in maintaining a healthy oral environment.