Journal of Dental Research, Vol 69, 1309-1315, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Facts and artefacts in research on human dental plaque fluid
A. Tatevossian
In 1966, Jenkins suggested that the plaque fluid environment was likely to
have higher concentrations of extracellular solutes than was apparent from
analyses of total plaque concentrations. Early work on plaque fluid
confirmed this contention, but some artefact was also generated by the
prolonged centrifugation used for separation. The solute concentrations in
plaque fluid mostly exceed those in saliva or crevicular fluid. Thus, the
environmental conditions are distinctly different from those based on the
assumption that saliva readily permeates films of dental plaque. In
contrast, the presence of serum proteins suggests a crevicular input to
plaque fluid. These data suggest that exchange between dental plaque and
its environment is apparently restricted. Diffusion rates measured in
dental plaque by different methods do not agree on how restricted it is.
However, measuring diffusion in plaque introduces artefacts in packing
density, a major determinant of the diffusion rate. The conditions used for
collection and analysis have been reported to produce artefactual changes
in plaque fluid potassium, a predominantly intracellular ion. Measurements
of predominantly extracellular ions, such as calcium, are no less prone to
artefact, whether based on ion-selective electrodes or on total calcium. We
have much to learn about the fluid environment of the teeth and about
dynamic changes in plaque fluid composition and properties during
perturbations. Such information can give insights into pathological
processes such as tooth demineralization and dental caries, calculus
formation, and gingival inflammation.
