Salivary Stimulation and Plaque pH

The fact that saliva is so beneficial in terms of buffering and neutralizing acidic plaque pH values has stimulated much interest in agents that increase salivary flow rates.14 Chewing gum or unflavored materials such as paraffin wax after consuming fermentable carbohydrates leads to an increase in salivary flow with a concurrent rapid rise in plaque pH. This rise has been shown to be closely associated with a rise in bicarbonate buffering capacity, as well as an increased supply of nitrogenous substrates, which are metabolized to basic (less acidic) end products.14-16 The chewing of cheeses rich in nitrogenous compounds gives rise to similar pH increases found with paraffin wax, despite the cheese itself being acidic. This is probably due to the breakdown of casein and other cheese proteins, as well as the fact that cheese is a strong sialogogue, an agent that increases the flow of saliva. Cheese has the added advantage of raising the plaque concentrations of calcium and phosphate and, therefore, increasing the chance of remineralizing teeth.16

Figure 8. Plaque pH responses by a sugar-rich snack alone, and followed by sugared or sugar-free chewing gum.

Adapted from: Manning RH, Edgar WM. pH changes in plaque after eating snacks and meals, and their modification by chewing sugared- or sugar-free gum. Br Dent J. 1993;174(7):241-244.

Figure 9. Plaque pH responses to a sucrose mouthrinse alone, and followed by paraffin or cheese.

Adapted from: Higham SM, Edgar WM. Effects of Parafilm and cheese chewing on human dental plaque pH and metabolism. Caries Res. 1989;23(1):42-48.