Vascular permeability during initial gingivitis in dogs

Variations in the permeability of dento-gingival blood vessels during initial gingivitis have been studied in four beagle dogs. On two occasions during a four-day period of developing gingivitis, increased permeability of the dento-gingival blood vessels was provoked by inserting filter paper strips into the dento-gingival junction. Vessels in a state of abnorma permeability were labelled on one occasion during the four-day period by intravascularly injected colloidal carbon and by fluorescent microspheres on the other occasion. The vascular labelling scores for each of the two tracers were determined in gingival biopsies. An experimental outline was used which allowed comparison of the permeability characteristics of the vessels on day 0 with those on day 2 and on day 2 with those on day 4 of the initial gingivitis.
At each time interval (day 0, 2 and 4) the vascular labelling of the dento-gingival blood vessels was found evenly distributed in the coronal-apical direction of the vascular plexus. The labels were most frequently found in vessels 10–50 microns in width. In three of the dogs the vascular label scores were found to be significantly higher on day 2 compared with day 0 and on day 4 compared with day 2.
The results indicate the development of a vasculitis in the dento-gingival blood vessels during initial gingivitis involving most vessels of venular type in the vascular plexus.