Salivary and plaque acids in caries active and caries free subjects

The levels of organic acids in the plaque and saliva of 30 subjects aged between 12 and 20 years were investigated. Fifteen of the subjects were caries free and 15 had active carious lesions. The variables examined were the DMFT, plaque index, bleeding index, the flow rate of saliva, daily intake of fibre and sucrose and the level of acids in resting plaque and saliva exposed to a glucose rinse. Posterior bitewing radiographs were taken to confirm the presence of carious lesions. The Kruskal Wallis one-way analysis of variance was used to compare caries free and caries active subjects. Caries active subjects consumed more sucrose (p < 0.001) and had lower levels of acetic acid in their saliva (p = 0.05) than caries free subjects. The acetic acid-acetate buffer system can act as a buffer which suggests that acetic acid in the saliva of caries free subjects may diffuse into plaque to act as an effective buffer to counteract the destructive effects of lactic acid.