Journal of Dental Research, Vol 70, 1497-1502, Copyright © 1991 by International & American Associations for Dental Research Online Journals
In vitro acidogenic potential and mutans streptococci of human smooth-surface plaque associated with initial caries lesions and sound enamel
J. Van Houte, C. Sansone, K. Joshipura and R. Kent
Department of Oral Microbiology, Forsyth Dental Center, Boston, Massachusetts 02115.
Samples of human dental plaque were pooled from several "white spot" smooth
tooth surface areas as well as from several clinically-sound tooth surface
areas in each of 12 caries-positive college students. Each of the two
samples from each subject was used for the determination of: (1)
pH-lowering potential in vitro involving dispersed plaque suspensions,
excess glucose supply, and a 60-minute test, and (2) the proportions of
mutans streptococci and lactobacilli. When all subjects were considered,
plaques from "white spot" areas, as compared with samples from sound
surface areas, were characterized by significantly higher proportions of
mutans streptococci, a lower starting ("resting") pH, a faster rate of pH
drop between pH 6.0 and 5.0, and a lower minimum pH of the suspension; the
lactobacillus proportions were generally very low in both types of plaques.
For individual subjects, however, the proportions of mutans streptococci in
plaque associated with "white spot" areas showed a wide range
(0.001-10.0%), and samples with high as well as low levels of these
micro-organisms could exhibit a high rate of pH drop and a low pH minimum.
This suggests that, besides mutans streptococci and lactobacilli, other
bacteria capable of acidogenesis at a low pH may contribute to the high
pH-lowering potential exhibited by many plaques.
