Changes in the masticatory muscles, periodontal tissues, and the pharyngeal ring in Wistar rats in chronic psychophysical stress.

Experimental studies performed on 120 male Wistar rats using morphometric and histological methods demonstrated changes in oral cavity tissues on exposure to chronic psychophysical stress (dosed swimming). The masticatory muscles showed foci of non-infective inflammation, dystrophic changes in muscle fibers, and contractures. The periodontal ligament showed impairments to the microcirculation with congestion of the venous bed, local bleeding into the tissue, changes in the directions of bundles of collagen fibers, and deformation of bundles. The tissues of the pharyngeal ring showed decreases in lymphocyte content, progressive loosening of connective tissue, and decreases in non-degranulated mast cell numbers, as compared with controls. The intensity of these changes depended on the level of physical loading and the individual adaptive capacity of the animals. These structural changes in the tissues may be the etiopathogenetic basis of the development of chronic inflammatory periodontal diseases.