National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

Decalcification of tooth enamel begins at a pH level of 5.5. This is significant because enamel, being a mineralized tissue primarily composed of hydroxyapatite, begins to lose its mineral content under acidic conditions. When the pH of the oral environment drops below this threshold, the solubility of hydroxyapatite increases, leading to the dissolution of enamel minerals.

The critical pH level of 5.5 is often referred to as the 'critical pH' for enamel, indicating the point at which demineralization starts to occur. This understanding is crucial for dental hygienists and practitioners as it emphasizes the importance of maintaining a neutral or slightly alkaline oral environment to protect tooth enamel from caries and erosion.

Thus, monitoring dietary habits and oral hygiene practices that can influence the pH levels in the mouth is vital for preventing dental decay and preserving the integrity of tooth enamel.