Gingiva

GINGIVA, part of the mucous membrane of the oral cavity, covering the alveolar processes of the jaws. The gums consist of a richly vascularized connective tissue base, constructed from densely arranged powerful bundles of collagen fibers (among which elastic fibers are also interwoven), without a sharp boundary transitioning into the periosteum of the alveolar process; the latter circumstance determines the density, as well as the immobility, non-movability of the gingiva in relation to the underlying tissues. The density of the connective tissue base throughout the entire thickness of the gingiva and the absence of the so-called submucosal layer also explain 1) the paler, compared to adjacent areas of the mucous membrane, shade of its color and 2) the clinical observation according to which hemorrhages and edemas of adjacent parts of the mucous membrane as a rule do not spread to the area of the gingiva, sharply stopping at the border with it; only when transitioning to the mucous membrane of the hard palate, the boundaries of the gingiva are not sharply defined. The connective tissue base of the gingiva is covered by a layer of stratified squamous epithelium, slightly keratinized on the surface. At the boundary between the epithelium and the connective tissue base, a well-expressed papillary layer is noted. The connective tissue papillae are especially strongly developed at the free edge of the gingiva; here they penetrate so deeply into the epithelial layer that they are separated from the surface by only a few layers of epithelial cells. In each papilla there is a vascular-nerve bundle, which explains the bleeding of this area of the gingiva, manifested with the most insignificant damage to its covering [see separate table (p. 483-484), fig. 5]. Typical for the mucous membrane glands, except for the so-called incisive gland (glandula incisiva), located on the lingual surface in the area of the lower incisors, are not present in the gingiva. The mentioned incisive gland is considered as a part that has separated from the submandibular salivary gland. The exceptional rarity is the presence of sebaceous glands in the gingiva; the presence of the latter in unusual places in the oral mucous membrane is generally noted in patients with seborrhea. It should also be mentioned the epithelial formations described by Serres in the gingiva of newborns and accepted by him as glands; in fact, these conglomerates of concentrically arranged, flattened epithelial cells represent remnants of the dental lamina, immersed in the underlying connective tissue during the laying of teeth in the embryonic period; recently, similar epithelial remnants have also been described in the gingiva of adults and even elderly people (Lund). The part of the gingiva located above the bony edge of the alveolus and filling the interdental spaces is called the gingival papillae; they are the sites of transition of the gingiva from the vestibular surface of the alveolar process to the lingual (and palatal). In humans, as a rule, the connective tissue base of the gingival papillae is penetrated by accumulations of round cells of the lymphocyte type; this cellular proliferation is most pronounced directly under the epithelial covering, gradually disappearing in the depth [see separate table (p. 483-484), fig. 5]. Sometimes it is so abundant that the fibrous structure of the connective tissue in these areas seems to be erased; in connection with this, there is less density of tissue in the gingival papillae compared to other areas of the gingiva. Previously, it was believed that the side facing the crown of the tooth, the free edge of the gingiva only adjoins the surface of the crown, so that between them there is a slit-like space—the gingival pocket, the bottom of which is located approximately at the level of the enamel-cement junction. On the basis of new research (Gottlieb), the erroneousness of such a view has been established. In fact, the normal relations are such that adhesion and therefore the presence of a slit-like space exists only over a very limited extent (about 2 mm in depth from the free edge of the gingiva). On the remaining extent toward the neck of the tooth, the surface of the epithelium is organically fused with the Nasmyth's membrane of the enamel. Thus, the bottom of the gingival pocket is located above the enamel-cement junction corresponding to the place where the epithelium of the gingival pocket separates from Nasmyth's membrane of the enamel [see separate table (p. 483-484), fig. 6]. It should be noted that at the boundary between the connective tissue and the epithelium facing the surface of the crown, the papillary layer is almost completely absent. In the order of embryonic development, the gingiva as a separate part of the oral mucous membrane appears simultaneously with the formation of the alveolar processes. The differentiation of gingival papillae and the area of gingival pockets coincides with the moment of tooth eruption. Atrophic changes in the gingiva also represent only sequential phenomena accompanying the atrophy of the alveolar processes. In the light of these facts, the tissue of the gingiva appears not as an independent formation, but as part of the paradentium. The blood supply to the gingiva comes from the branches (rami gingivales) of the aa. alveolar, superiores anteriores et posteriores and aa. palatinae majores on the upper jaw and aa. alveolares inferiores and their branches (rami mylohyoidei) on the lower jaw. Special mention should be made of the nutrition of the gingival papillae, into the substance of which pass the terminal branches of aa. interalveolares, located in the bony septa between the alveoli. The collectors of venous blood for the area of the gingiva are the facial veins (vv. facialis anterior et posterior). The lymphatic vessels of the gingiva, representing an extremely delicate, narrow-meshed network, on the vestibular surface of the alveolar processes of the upper and lower jaws collect into 3-4 common collectors and go to the submandibular area, following in the general course of the facial vein, to all three groups of submandibular lymph glands. Sometimes lymphatic trunks of the gingiva from the area of the frontal teeth go to the submental lymph glands. Lymphatic collectors from the