Which of the following is true about saliva's role during acid challenges?

• A. It inhibits demineralization during low pH
• B. It promotes remineralization when pH returns to neutral
• C. Both A and B
• D. It has no effect

Answer: (C)

Saliva protects teeth in two ways during acid challenges. First, it acts as a buffer. Its bicarbonate and other buffers neutralize acids produced by dental plaque, raising the pH at the tooth surface and reducing the driving force for mineral loss. This helps prevent demineralization even when a low pH challenge occurs. Second, once the acid is cleared and the environment moves back toward neutral, saliva supplies calcium and phosphate ions and facilitates their deposition into demineralized areas, promoting remineralization and repair. So saliva both limits dissolution during acidity and supports rebuilding after the pH has stabilized.