The purpose of this study was to examine the vascular network beneath the reduced enamel epithelium (REE) and oral epithelium (OE) during tooth eruption. Using the corrosive-resin casting method, vascular resin casts were prepared from premolar and molar teeth of the dog and examined by scanning electron microscopy. The vascular network beneath the REE is arranged in two layers, an inner layer consisting of a dense capillary network and an outer layer composed primarily of arterioles and venules. Throughout tooth eruption, the configuration of the vessels of the inner layer is continually changing from a network of capillary loops to a fishnet pattern, whereas the arrangement of the vessels of the outer layer remains fairly constant. When the crown emerges into the oral cavity, leakage of resin from the vessels provides evidence of increased vascular permeability, suggesting the presence of inflammation within the marginal gingiva. When root development is nearly complete, the vascular network adjacent to the REE becomes continuous with that of the OE. The inner margin of the free gingiva receives its blood supply from this network, and the vessels of this network also give off branches which anastomose with the capillary network of the periodontal ligament.
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