Changes in the functioning of the periodontal defence system in periodontal diseases

Abstract

Abstract. The study of lipid peroxidation processes and the antioxidant defence system in the pathogenesis of various pathological conditions, including periodontal disease, is currently receiving considerable attention, despite the fact that this topic appears to be well established. Lipoperoxidation is recognised as a crucial factor in the pathogenesis of the inflammatory process. Reactive oxygen species, such as superoxide anion, hydrogen peroxide, hydroxyl radical, and hypochlorous acid, are byproducts of normal cellular metabolism that are constantly and intentionally produced by the body. They play a vital role in the regulation of many essential processes, including phagocytosis, synthesis of group D, E and F prostaglandins, mitochondrial respiration and peroxisomal oxidation. The same or different reactive oxygen species, depending on the conditions, can both stimulate and inhibit cell division, stimulate the expression of various genes, cell differentiation in embryogenesis and even carcinogenesis, and affect apoptosis by generating chemical signals. However, excessive free radicals can damage cell membrane structures. The peroxidation of membrane phospholipids results in the accumulation of hydroperoxides, which leads to the formation of clusters and subsequent membrane fragmentation. This process also alters the membrane's permeability to Na and Ca ions. Inactivation of the Ca2+ transport enzymes ATPase leads to a slowing down of the calcium efflux from the cell and at the same time to an acceleration of its penetration into the cell, thus damaging it. Changes in the rate of reactive oxygen species formation can affect peroxidation, which may self accelerate and lead to the complete destruction of unsaturated lipids, disruption of the structure and function of proteins and nucleic acids, and ultimately cell death. These biochemical effects manifest as exudation and proliferation reactions in the inflammatory focus. Intoxication, microcirculatory disorders, autosensitization, and immune response disorders can lead to pathological regulation and inadequate adaptive responses at the organismal level. Clinical studies have also experimentally demonstrated the key role of the antioxidant system in the metabolic correction of the redistribution of energy substrates, its impact on the structural and functional state of membranes and the receptor sensitivity of cells.