Journal of Dental Research, Vol 64, 786-792, Copyright © 1985 by International & American Associations for Dental Research Online Journals
Importance of high pKA acids in cariogenic potential of plaque
H. C. Margolis, E. C. Moreno and B. J. Murphy
Through the use of computer simulation, it is shown that anions of high pKA
acids (e.g., acetic, propionic, butyric), present in resting plaque fluid,
act as effective buffers during the production of stronger acids (e.g.,
lactic) by oral micro-organisms. Using reported organic acid compositions
for plaque, obtained from caries-resistant and caries-susceptible
individuals, analyzed at various times following sucrose exposure, it is
shown that the calculated pH values of the aqueous phase of plaque describe
typical Stephan curves. Furthermore, it is shown that for higher acid anion
contents in resting plaque, a higher degree of saturation of the aqueous
plaque phase with respect to enamel is maintained during acid production,
resulting in a lower demineralization potential of plaque. Enamel
demineralization experiments conducted in vitro confirmed the significance
of the results of the computer simulations, thus providing evidence for a
correlation between the known metabolic activity of plaque (organic acid
composition), physical chemistry of plaque, and caries susceptibility.
