A Comparative Study of Connective Tissue Metabolism Indices in Experimental Comorbidity-Free Periodontitis and Periodontitis Combined with Thyroid Dysfunction

Periodontal disease is a chronic bacterial infection characterized by persistent inflammation, connective tissue breakdown, and alveolar bone destruction. The current study aimed to compare the connective tissue metabolism indices in rats with comorbidity-free periodontitis and in animals with periodontitis in a setting of hyper-and hypothyroidism. 12-14-week-old inbred white male rats (n=48) were included in the experiment. They were randomly divided into the following groups: control, animals with a model of periodontitis, animals with periodontitis in a setting of hyperthyroidism, animals with periodontitis in a setting of hypothyroidism. Serum levels of free thyroxine, free triiodothyronine, and thyroid-stimulating hormone were assayed using ELISA kits manufactured by Vector Best (Russia) to confirm the hyper- and hypothyroid status. Collagenolytic activity, the content of glycosaminoglycans, free hydroxyproline, and fucose, unbound with proteins in blood serum were assayed using the spectrophotometric method. We have found the increasing of collagenolytic activity by 46.1% (р<0.001), the content of free hydroxyproline by 74.1% (р<0.001), the content of glycosaminoglycans by 1.8 times (р<0.001), the content of fucose, unbound with proteins by 2.8 times (р<0.001) in rats with periodontitis vs. the control group. The development of periodontitis in a setting of thyroid dysfunction leads to an even more significant increase in the destruction of connective tissue, which is confirmed by a significant increase in the content of studied indices vs. euthyroid animals, both in hyperthyroidism and hypothyroidism.