Molecular Transport in Micro-Volumes Simulating Salivary Retention Areas

¹ Walter G. Zoller Dental Clinic, University of Chicago, Chicago, Illinois

1. The transport of ions and molecules in narrow chambers from the surrounding bulk solutions by diffusion alone is very slow.

2. Transport from a highly concentrated solution surrounding a narrow space is not greatly facilitated, unless the internal solution of the chamber is constantly relatively dilute.

3. Osmolality and density differences between the internal and external solutions are responsible for rapid transport rates.

4. The rapid transport of a solute from the external solution to the inside of a narrow chamber occurs if the osmolality and/or the density of the former is either greater or lesser than that of the latter.

5. Osmolality and density differences may be created by high or low concentrations of one solute in either the interior or exterior compartments or by the presence of several other additional solutes in either chamber.

6. Rapid transport of a low concentration of a specific solute in an exterior solution may be obtained if the osmolality and/ or density of that solution is increased by a foreign or inactive compound and made greater than that of the internal solution.

7. The forced flow of an exterior solution is effective in mass transport into contact areas even when density and osmotic concentration gradients do not exist. A pulsating stream is many times more effective than continuous flow.

8. Single or infrequent conveyances of even concentrated solutions into micro-volumes of saliva occupying inter- and intradental spaces must result in a limited reaction effect due to the small volume of liquid exposed to the relatively very large tooth surface area.

9. If fluoride or other topically applied caries-inhibiting substances are indicated, such application would be accomplished most frequently and effectively with the daily use of a dentifrice containing modest and nontoxic amounts of the active compound supplemented with NaCl to increase osmolality and density factors. Obviously fermentable sugars should not be dentifrice constituents.

10. The habitual ingestion of concentrated (palatable) fermentable sugars produces frequent osmolality and density changes in bulk oral saliva with the resultant rapid and repeated conveyance of all constituents into micro-volume regions.

11. The habitual ingestion of highly salted foods produces frequent oral salivary osmolality and density changes and likewise facilitates the rapid and repeated conveyance of all constituents (even low concentrations of fermentable carbohydrates) into saliva retention areas.

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