Epidemiological studies of recent years have shown a high prevalence of periodontal tissue diseases in the world and in particular in Ukraine. Significant influence on the prevalence of periodontal tissue diseases in the population is caused by many factors: this is the climatic conditions of the area and the general level of health of the population and the ecological situation in Ukraine and social conditions of life. One of the main common factors in the development of periodontal tissue diseases is the presence of concomitant pathology. Despite the current trends in dentistry to improve diagnostic and treatment methods, the introduction of advanced medical technologies, a significant reduction in periodontal disease among adult Ukrainian population is not observed.
 The aim of the study. To study the prevalence and structure of periodontal tissue lesions in patients with general - somatic diseases in order to develop a therapeutic algorithm in a hospital setting.
 Materials and methods. A common clinical dental examination of 512 patients from different departments of LRCH was carried out. Generalized periodontitis was diagnosed according to generally accepted clinical and pair clinical methods with the definition of periodontal index (PI) by Russel (1956); index of PMA for Parma (1960); functional stability of capillaries (FSK) for V. Kulazhenko in the dynamics of treatment. The state of oral hygiene was assessed before and after treatment with the Green-Vermillon Hygiene Index (GI) (1964). To establish the diagnosis, the classification of diseases of periodontal tissues by M.F. Danilevsky (1994) was used. About the state of the bone of the alveolar sprout were judged by the results of the X-ray examination, which was conducted according to indications and standardization of X-ray studies in dentistry NA Rabukhina (1991). It was mandatory to analyze a general clinical examination of blood. The degree of validity of the difference between the two averages was determined using the unilateral criterion (t) of the Student. The difference in the rates was considered reliable at t≤1.96, which corresponds to the required level of reliability for clinical studies with a reliability of the findings - 95.0% and a high level of their non-falsity (р˂0.05).
 Research results and their discussion. As a result of our research, we have established the following laws: in individuals of the Department of Cardiovascular Surgery, neurological and gastroenterological departments, the prevalence of nosological units of periodontal tissue was the same and did not differ with the probability of the data obtained among themselves; in patients with rheumatologic department, a significant prevalence of inflammatory diseases of periodontal tissues and initial forms of GP was determined by the decrease of the prevalence data of developed forms of GP in relation to the corresponding values in patients of other departments.
 Conclusions Consequently, as a result of our research, we found that the prevalence of periodontal tissue diseases in patients from different branches of LOCН was 75 %, which according to WHO criteria was characterized as high. With the increase in the age of those surveyed with various somatic diseases, the prevalence of lesions of tooth-retaining tissues increased: from 46.13% in patients ≤ 20 years old, to 88.15% in patients aged ≥ 50 years. More often in patients with concomitant somatic pathology, chronic generalized periodontitis were diagnosed in 65,63% of the examined patients. The inflammatory (6.25%) and dystrophic (7.62% of patients) periodontal tissues were significantly less likely to be detected. In patients with cardiovascular and rheumatologic diseases, the frequency of lesions of periodontal tissues was higher than in patients with neurological and gastroenterological diseases, which may be a significant factor in the development and course of periodontal pathology.