MICROBIOLOGICAL ASPECTS OF THE PATHOGENESIS OF PERIIMPLANTITIS

  The study of the spectrum of microorganisms, microbial associations and successional changes in the peri-implant zone under conditions of peri-implantitis is of crucial importance for improving methodological approaches to the treatment of patients with orthopedic structures supported by dental implants. The results of whole-genome sequencing prove that peri-implantitis is caused by diverse and complex microbial associations, different from healthy peri-implant areas and periodontal tissues. Identification of bacterial predictors is a crucial prerequisite for the development of effective preventive strategies and targeted interventions, and screening of microbial profiles under pathological conditions forms the basis for the development of effective preventive and therapeutic strategies. The purpose of the study is to study the microbial profiles of the peri-implant microbiota in conditions of peri-implantitis. Materials and methods. A comprehensive examination of 252 patients of both sexes aged 25-65 years (120 men and 132 women) with peri-implantitis was conducted. Cases of peri-implantitis with moderate and severe course were diagnosed according to the Renvert-Claffey classification (2012). The microbiota of the examined patients was studied, for which 491 bacterial isolates were isolated from the focus of the inflammatory process. As a control, the microbiota of periodontal tissues of healthy patients without signs of inflammatory periodontal diseases (n=74) was studied. The material was sown on nutrient media by the Gold sector culture method on differential diagnostic nutrient media ("Himedia", India). For the cultivation of anaerobic representatives of the microbiota, the nutrient medium Schadler agar + 5% sheep blood ("Himedia", India) was used. To create anaerobic conditions, an anaerostat with a system for providing anaerobic conditions (AnaeroGen System – “Oxoid”, Great Britain) was used. Identification was carried out by morphological, tinctorial and biochemical signs using the systems for identification “ENTERO-test”, “STREPTO-test”, “STAPHY-test”, “СANDIDA-test” manufactured by “Erba Lachema” (Czech Republic). Identification of isolated pure cultures of anaerobic bacteria was carried out using MALDI-TOF. Results. According to the results of the conducted studies, dysbiotic disorders of the microbiota in the peri-implant area were established in patients with clinical signs of peri-implantitis. Categorization of clinical isolates by genus demonstrates that under peri-implantitis conditions, the highest level of persistence was characteristic of bacteria of the genus Streptococcus spp. The percentage of their detection among microorganisms isolated from the focus of the inflammatory process was 41.14% in titers from 10⁶ to 10¹² CFU/ml. In 15.54% of cases, an association of bacteria of the genera Streptococcus spp.+Porphyromonas spp. was isolated from the focus of the inflammatory process, and in 12.16% of cases - Streptococcus spp.+Prevotella spp. With a frequency of 11.49±0.5, an association Peptostreptococcus spp.+Porphyromonas spp. was isolated, which is characterized by the presence of two anaerobic bacteria belonging to the orange and red Sokransky complexes, respectively. Analysis of triassociative microbial complexes shows that the highest level of persistence was characterized by the microbial association Peptostreptococcus spp.+Streptococcus spp.+Staphylococcus spp., which was isolated with a frequency of 20.51%, and Streptococcus spp.+Prevotella spp.+Enterobacteralis spp. - with a frequency of 17.94%. Both associations combine one periodontal pathogenic species and two conditionally pathogenic species of facultative microbiota. An increase in the titer level of bacteria of the genus Streptococcus in conditions of peri-implantitis indicates the role of this genus of bacteria in the pathogenesis of inflammation. Conclusions. The results indicate that changes in the peri-implant environment under inflammatory conditions are accompanied by successional changes in the qualitative and quantitative composition of the microbiota, leading to the development of dysbiosis. The established patterns indicate the relationship of peri-implant inflammation with changes in the structure of the microbial profile, including the formation of polymicrobial complexes in titers of 10⁶-10¹² CFU/ml with the prevalence of anaerobic periodontal pathogens and pathogens of opportunistic infections. The restructuring of microbial associations is accompanied by a change in the ratio and number of microorganisms, which serves as a prerequisite for the occurrence of inflammatory processes in peri-implant tissues. Noting the individual composition of the oral microbiota, it should be stated that the genus Streptococcus is the dominant genus of the oral microbiome, both in normal and in conditions of inflammatory process. The obtained results emphasize the importance of microbial screening for optimizing antimicrobial therapy and developing preventive strategies in the treatment of patients with peri-implantitis. The cultural method of research, despite the development of molecular genetic technologies, remains relevant for clinical practice, as it allows the identification of bacterial biomarkers and the determination of their sensitivity to antibiotics.