Effect of Acetic, Lactic and other Organic Acids on the Formation of Artificial Carious Lesions

Artificial carious lesions were produced in human enamel using a diphosphonate/organíc acid system over periods up to 30 days, and progress assessed by depth measurement. Acids studied were lactic, acetic, propionic, isobutyric, succinic, tartaric, hydrochloric and hydrofluoric. The rate of lesion progress was found to be a function of calculated unionized acid concentration, and acid dissociation constant. Acetic acid made a major contribution to the rate of lesion formation, even at pH 5.0 or higher and is likely to be as important as lactic acid in the in vivo caries situation. Mixtures of acetic and lactic acid had additive demineralizing properties. This emphasizes the importance of acid type and concentration rather than pH alone.