INCREASING THE STABILITY OF DENTAL SOLID TISSUES TO STRESS BY IODINE-CONTAINING THYROID HORMONES

Goal. To study the effect of the thyroid status on the resistance of enamel and dentin to caries under stress as well as to reveal its mechanisms, associated with the action of iodine-containing thyroid hormones on the structural and functional stability of the enamel, mineralizing properties, calcium concentration and lipid peroxidation intensity in saliva. Material and methods. The experiment was carried out on 210 mongrel male rats that were kept under crowding stress conditions starting from the 21st day of age (40 individuals in a cage during the first month, 30 – during the second month). Thyroid hypothyroidism was modeled by intragastric administration of Mercazolil at a dose of 25 mg/ kg during the first month followed by a half dose until the end of the 2nd month. L-thyroxin was administered in the same way in close to physiological doses (from 1.5 to 3.0 μg/kg for 4 weeks, then 1.5 μg/kg until the end of the study). Results. It has been established that hypothyroidism increases, while small doses of L-thyroxin, on the contrary, reduce the prevalence, frequency, severity and depth of carious lesions of enamel and dentin under stress conditions due to an increase in the structural and functional stability of enamel, as evaluated by the test of enamel resistance, due to improvement of remineralization properties of saliva (microcrystallization of saliva and its mineralizing potential), as well as due to an increase in the calcium content and the activity of antioxidant systems in the enamel, which limits the activation of lipid peroxidation. Conclusion. A new aspect of the participation of iodine-containing thyroid hormones in the anti-stress system has been established, which consists in increasing the resistance of hard tooth tissues to caries under stress.