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ECPB 2014, 68(4): 34–39
Experimental physiology and biochemistry

Features of the morphological organization of the parodontium of rat in norm


The experiment was carried out on 12 «Wistar» rats, weighing about 160 g, 3,5–7,5 months of age. The upper and lower jaws with soft tissues (periodontal) were taken for the samples after the thiopental overdoses (with 25 mg/kg). Before this the visual inspection of oral mucosa was made – it was pale pink, moderately hydrated, without any sigh of pathology. The samples were fixed in 10% formalin for 24 hour. We have made a practical model of decalcification of the dental hard tissue with the aim to remain the anatomical elements ratio, to use these samples in further micro structural researching in normal and pathological conditions. The method, which we have proposed, was proved in practical experiment, thus dental tissues samples were easily sliced with microtome for further histology examination [6].

After the examination of the samples it was found that the periodontal tissue consists of different type of tissue. Parodontium is morpho-functional complex of tissues which surrounds the tooth and together they tightly bounds to each other morphologically and functionally. To the parodontium structures belongs osseous tissue with periosteum of alveolar processus of the jaw, which is adjacent to the root of the tooth, alveolar socket, dental cementum, vessels and nerves of the tooth, gingiva, periodont, and dental ligament. Alveolar part of the upper and lower jaws, in which roots of the teeth are located, is covered with the cortical plate of the compact substance of bone and continues into the paries of the alveolar socket, formed with the osseous plates and penetrated by the big quantity of filaments. Cortical plate has in its complex osteons and osseous laminas, on the surface of which areas of reticulated bone is differentiated. Cement is an integral part of fixative apparatus of the tooth. The primary cement located near the neck of the tooth and is made from the collagen fibers and from sticking agent. The secondary cement consists of collagen fibers, intercellular substance and cementocytes. The rat’s gums have free (marginal) and fixed (alveolar) parts. The marginal part surround from all sides the distal part of the clinical crown of the tooth and continues into the gums margin. The alveolar part of the gums strongly fixed with the periosteum of the alveolar processes of the jaw, thus there is no submucous layer in this area.

There is stratified squamous epithelium with sign of keratinization in free part, and non keratinizing stratified epithelium in the marginal part of the gingiva. The sulcus gingivalis is a space which borders with the surface of tooth crown neck medially, by the internal surface of the free part of the gums laterally; epithelial connection of the free part of gums forms the bottom. Besides, the circular ligament of tooth participates in the periodontium and in the bottom of sulcus gingivalis.

Connective tissue of the periodontium fills the space between the tooth cement and of the root and periosteum of the alveolar socket. The structures of periodontium and sulcus gingivalis are very important in a case of toxins which can destroy the epithelium junction, thus the infection can passes through and cause pathological process in periodontium tissues. Thus, our experimental morphological research of the tissues of the periodontium in normal condition gives us opportunity to compare it with experimental pathology in this area, as well as to found better terms for correction.

Keywords: parodontium, rat, periodontium, gingival

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