A New Way to Model Periodontitis in Laboratory Animals.

The prevalence of periodontal diseases is increasing, tends to increase with age and is considered as one of the main causes of tooth loss. To assess the effectiveness of new methods of treatment of periodontal diseases, studies on laboratory animals can be promising. THE AIM OF THE STUDY: to develop a new method of accelerated modeling of experimental periodontitis on laboratory animals. MATERIAL AND METHODS: The study was carried out on 22 female rats. A wire ligature was applied to the cervical area of the incisors of the animals in an eight-shaped manner. Plaque obtained from a patient with periodontitis was placed under the wire, and nicotine and ethyl alcohol solutions were injected under the gingival mucosa. A complex index has been proposed to assess inflammation. At the end of the experiment the animals were euthanized, their jaws were dissected into dentoalveolar blocks and further descriptive histologic analysis was performed. RESULTS: On the second day the gingiva of the rats acquired a cyanotic-pink color, on the fourth day the consistency of the gingiva became friable, mobility appeared in the lower incisors. Complex index of inflammation in animals of the main group: before the study-9, on the 7th day-195. Gingival preparations showed signs of exudative inflammation. In alveolar processes-irreversible resorption of bone structures. The difference of indicators in animals before and after the experiment was statistically significant (p < 0.05). CONCLUSION: The new experimental model of periodontitis is reproduced in a short period of time, provides intensive development of inflammation, leads to disruption of the integrity of epithelial and connective tissue attachment, destruction of alveolar bone.

AB0 and rhesus blood groups as a risk factor for ARVI COVID-19.

The frequency of AB0 and Rhesus blood groups was studied in 12120 patients with COVID-19, 5180 convalescent plasma donors and 118801 healthy donors from Moscow, Smolensk, Yakutsk, Minsk and Gomel. In infected individuals, the frequency of blood group A was significantly higher than in uninfected individuals (41,54 % and 34,39 % respectively, p<0,05), and the frequency of blood group 0, on the contrary, was significantly lower (27,69 % and 36,71 %, p<0,05). The frequency of blood group A was particularly high among patients who died from ARVI COVID-19 - 45,51 % vs. 34,39 %, p=0,008. In some groups of patients, there was a decrease in the frequency of Rh-negative individuals (2,23 % vs. 8,30 %, p<0,001).