Age changes in the blood supply to molar teeth of rats

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Abstract
1. Rats, varying in age from one month to over one year, were used to study the changes in the vascular supply to the molar teeth and periodontium as a result of aging. The blood vessels were demonstrated by the saline‐India‐gelatin perfusion method. The jaws and teeth were fixed in a formol‐acetic acid‐alcohol solution, decalcified, dehydrated, and embedded in nitro‐cellulose in the usual manner. The embedded specimens were sectioned at 100–250 μ, cleared by the Spalteholz method and mounted unstained.2. In immature animals (younger than four months) the pulpal terminal vascular capillary networks were located at the predentin border. As the animals became progressively older, there was a gradual “withdrawal” of the terminal capillary plexuses from the odontoblastic zone so that at eight months of age, all the vascular terminals were restricted in location to the pulpal‐odontoblastic border.3. In the young animal the vessels supplying the periodontal ligament passed gingivally paralleling the bony surface of the membrane with the cemental side being devoid of vessels. During the process of aging, the above basic pattern was altered in the following manner: (a) The apposition of cellular cementum on the apical third of the root was accompanied by the presence of capillary terminals in or adjacent to the layer of cellular cementum. (b) There was a progressive decrease and eventually a loss of the interseptal vessels and their perforating branches. (c) Vascular twigs originating from the main periodontal vascular trunk were found in areas of cemental resorption indicating their need in the process of repair.
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