Journal of Dental Research, Vol 71, 1304-1309, Copyright © 1992 by International & American Associations for Dental Research Online Journals
Changes in the microvasculature after mechanical pressure on the hamster cheek pouch
J. Iida, S. Inage, S. Kurihara and F. Miura
First Department of Orthodontics, School of Dentistry, Tokyo Medical and Dental University, Japan.
The reaction of the microvasculature in the periodontal ligament to
mechanical pressure is considered a very important phenomenon with respect
to the biological background to orthodontic tooth movement. For
clarification of the microvascular reaction to mechanical pressure, an
experimental model that incorporated a hamster cheek pouch was established.
This in vivo model solves some of the problems of other experimental models
of the microvasculature of the periodontal ligament. Blood plasma
permeation in this model was examined by means of a blue dye (pontamine sky
blue), and histological observation was performed by light and transmission
electron microscopy. Increased vascular permeability was observed within 30
min after removal of the mechanical stimulation. The threshold weight
resulting in dye leakage was between 1 and 5 g applied for 60 min. From the
histological observations, some large gaps between the endothelial cells in
venules were found, while most basement membranes remained undisturbed.
These observations suggest that the plasma leakage was due to mild
traumatic injury to the endothelial cells. Both leukocytes and platelets
were observed in the gaps between the endothelial cells in the venule.
These types of microvascular reactions to mechanical pressure could
initiate tissue changes in the periodontal ligament during orthodontic
tooth movement.
