Subject. Currently, about 530 types of microorganisms that live in supragingival and subgingival plaque have been discovered. To periodontal pathogens today carry a little more than ten types. The main role in the occurrence of periodontal disease is played by microorganisms included in the “red complex” of BANA+: Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia. With the simultaneous identification of these types can be judged on the high risk of developing periodontal disease. Objective ― calculating the frequency of occurrence of various types of dentition defects of patients with varying severity of periodontal disease, establishing the connection between the severity of periodontal disease and the number of periodontal pathogenic microflora. Methodology. A clinical examination of a patients group which consists of 32 women and 10 men in the age from 38 to 66 years was conducted. Anamnesis was collected using a survey and a special questionnaire. External examination and examination of the oral cavity allowed to find the clinical conditions and anatomical features that leads to periodontal disease’s development. Results. Based on the data of clinical and radiological examination, the patients were divided into three groups according to the severity of periodontal disease. During the clinical examination, we calculated the frequency of occurrence of various types of dentition defects in patients with varying degrees of severity of periodontal disease. Findings. It has been found that the course of chronic generalized periodontitis depends on the number of types of aggressive forms of periodontal pathogens.