Journal of Dental Research, Vol 71, 1792-1796, Copyright © 1992 by International & American Associations for Dental Research Online Journals
Effect of delmopinol on the cohesion of glucan-containing plaque formed by Streptococcus mutans in a flow cell system
J. Rundegren, T. Simonsson, L. Petersson and E. Hansson
Department of Biology, Biosurface AB, Malmo, Sweden.
Glucan-containing plaque was formed by Streptococcus mutans adhering to
saliva-coated glass slides in flow cells thermostated at 37 degrees C. The
substrate was Brain Heart Infusion broth containing 1% sucrose and 10%
sterile saliva. During the build-up of the plaque, which lasted for 29 h,
the plaque was subjected to three two-minute exposures to either 0.1 mol/L
sodium acetate buffer, pH 6.0, or the same buffer containing 6.4 mmol/L
(0.2%) of the surface-active anti-plaque substance delmopinol
hydro-chloride. The glass slides carrying the plaque were weighed, and
plaques subjected to delmopinol treatment weighed only seven percent of the
control plaques. The glass slides were then mounted in a beaker containing
buffer, subjected to ultrasonication, and re-weighed. The
delmopinol-treated plaques lost 59% of their wet weight upon sonication,
while the controls lost only 19%. Control plaques having the same weight as
delmopinol-treated plaques were not different from the control plaques
grown for 29 h with regard to reduction of plaque weight after sonication.
Transmission electron micrographs (TEM) showed a plaque dominated by
globular or fibrillar matrix components in controls, while the
delmopinol-treated plaque showed empty or unordered matrix areas between
more densely packed cells. The TEM results were confirmed by scanning
electron micrographs, which showed amorphous material associated with the
bacterial cells in the control but not in the delmopinol-treated plaque. In
conclusion, delmopinol reduced surface-associated glucan synthesis and
lowered the cohesion of the plaque, indicating that glucan-containing
plaque formed during repeated rinsings with delmopinol may be easier to
remove by mechanical means than a non-treated plaque of this type.
