Host Protective Properties of Saliva

Physical Protective Qualities
Due to its water content and flow rate, saliva physically cleanses the oral cavity of food and debris.¹⁴ Unstimulated flow rates are approximately 0.3 to 0.4 ml/min This rate decreases to 0.1 ml / min during sleep. While stimulated flows are approximately 1.5 to 2 ml/min, although there is great variability in individual salivary flow rates.¹⁰ Most humans produce roughly 0.5 to 1 liter of saliva per day with 90% secreted from the major glands. Saliva also dilutes and removes organic acids from dental plaque.¹²

Chemical Protective Qualities
Saliva contains a number of electrolytes and organic molecules that minimize decreases in local pH, creating an environment that favors remineralization. For example, sodium bicarbonate and phosphates, along with other salivary components, act as buffers or neutralizing agents in saliva. In addition, one salivary protein called sialin tends to raise salivary pH to neutral levels.

Saliva is also supersaturated with hydroxyapatite, fluorapatite, and calcium and phosphate ions compared to the carbonated hydroxyapatite in enamel. This supersaturation is maintained by the proline-rich proteins and statherins in saliva, and it increases the likelihood of remineralization via the incorporation of calcium and phosphate into enamel.^10,12

Antibacterial Protective Properties
Saliva contains several proteins with different types of antibacterial properties: The mucins are sulfated glycoproteins that trap, aggregate, and clear bacteria. The enzymes called amylases break down food particles that stick to teeth, reducing the bacterial build-up that can lead to decay.