Journal of Dental Research, Vol 66, 1614-1618, Copyright © 1987 by International & American Associations for Dental Research Online Journals
The influence of salivary flow rate on diffusion of potassium chloride from artificial plaque at different sites in the mouth
P. Lecomte and C. Dawes
Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Canada.
The rate at which substances diffuse from dental plaque influences the rate
of clearance of acid and bacterial toxins from plaque into saliva. The aim
of this study was to compare the rates of clearance of potassium chloride,
as a model substance, from artificial plaque of 3-, 4-, and 6-mm-diameter,
positioned bilaterally at different locations in the mouth. The diffusant
was KCl (1 mol/L) in a 1.0% agarose matrix, placed in wells 1.5 mm deep, in
small acrylic devices 3 mm thick, which could be fastened to the teeth with
dental floss and removed after different time periods. The half-time for
clearance was determined from the best-fitting least-squares line of the
potassium concentration remaining in the gel plotted against the square
root of time. For 14 subjects, half-times for the lower anterior lingual
and upper posterior lingual regions averaged about 2.5 times greater than
those for clearance into a large, stirred volume in vitro, whereas those
for the upper and lower anterior buccal regions averaged about 12.8 times
greater. This difference may be due to the fact that anterior buccal sites
are exposed only to minor rather than to major salivary gland secretions.
When salivary flow was stimulated by the sucking of sour lemon drops, all
in vivo half-times were reduced by about one-half. The half-times were also
directly related to the surface areas of the chambers, which implies that
rates of diffusion from plaque of substances such as acid or bacterial
toxins are inversely related to the surface area of the plaque at a
particular site.
