The authors analyze the role of the factors promoting a disruption of the physiologic antioxidant system, such as nervous stress, hypodynamia, bioantioxidant insufficiency, and inadequate pro-oxidant supply, to the development of peroxidation mechanisms of periodontitis initiation. The suggested concept implies that the general etiologic factors responsible for disruption of the physiologic system of lipid peroxidation inhibition create a background low-level antioxidant protection of the periodontal tissues. Under such conditions the local factors (dental deposit, plaques, microorganisms) conducive to neutrophil migration to the gingiva and gingival fluid lead to a break out of lipid peroxidation in soft tissues of the periodontium; this break out is induced by free radicals (O2- et al.) that are produced in "respiration explosion" of phagocytizing leukocytes. Regular outbursts of lipid peroxidation represent the trigger mechanism in the development of morphofunctional changes in the periodontium and its vessels, resulting in collagen destruction and bone tissue resorption. The authors emphasize the usefulness of antioxidants in drug prophylaxis of periodontitis.