Resting Plaque pH

This describes plaque that has not been exposed to fermentable carbohydrates for approximately 2 hours and generally has a pH of between 6 and 7. The resting plaque pH value for an individual tends to be stable and may remain so for long periods.9 One example of an exception is if antibiotics have been taken, which may alter the oral flora. There are relatively high concentrations of (less acidic) acetate compared with (more acidic) lactate in resting plaque, with the amino acids glutamate and proline being predominant.10 Ammonia, a pH neutralizer, is also present. These metabolic products are present in plaque in much higher concentrations than in saliva, partly because they are constantly produced from the intra- and extracellular metabolism of bacterial carbohydrate stores, as well as from the breakdown of salivary glycoprotein.6