PECULIARITIES OF REACTIVE CHANGES IN THE ORAL MICROBIOME AND MUCOUS MEMBRANE UNDER THE INFLUENCE OF FIXED ORTHODONTIC APPLIANCES: PATHOGENESIS AND IMMUNOLOGICAL ASPECTS (LITERATURE REVIEW)

Abstract

Introduction. The use of fixed orthodontic appliances is a highly effective method for correcting dentofacial anomalies; however, it significantly affects the oral microenvironment. Fixed structures cause continuous mechanical irritation of the oral mucosa and disruption of the microbiocenosis. These multifactorial changes initiate the development of inflammatory processes, caries, and periodontal diseases, which can negatively impact patient compliance and overall treatment success.
Objective. To analyze and systematize current scientific data regarding the pathogenetic interaction between the oral microbiota, the epithelial barrier, and the patient’s immune system during treatment with fixed orthodontic appliances.
Methods. A review of professional literature in the PubMed and Google Scholar scientometric databases for the years 2020–2025 was conducted. The search was performed using the following keywords: “fixed orthodontic appliances”, “oral microbiome”, “oral mucosa”, “microbiota dysbiosis”, “pathogenesis”, and “immune response”. Original and review articles investigating the impact of orthodontic intervention on the oral cavity ecosystem were included in the analysis.
Results. The literature analysis demonstrated that fixed orthodontic appliances cause epithelial microtraumas and create new retentive zones ideal for the accumulation of bacterial biofilms. A pronounced dysbiotic shift occurs as early as the initial stages of treatment: the alpha-diversity of the microbiota decreases, while the number of cariogenic and periodontopathogenic bacteria (specifically Streptococcus mutans and Porphyromonas gingivalis), as well as fungi of the Candida genus, rapidly increases. A crucial link in the pathogenesis is the shift of local pH toward alkalinity due to bacterial urease activity. This inactivates the protective enzymes of saliva and stimulates the growth of proteolytic anaerobes. The action of bacterial exotoxins leads to the disruption of epithelial tight junctions (the “leaky mucosa” effect) and initiates a robust innate and adaptive immune response, which sustains chronic inflammation and tissue destruction.
Conclusions. Orthodontic dysbiosis is characterized by a rapid reorganization of the microbial community, followed by its stabilization at a pathogenic level. The risk of developing caries and inflammatory diseases of the oral mucosa remains elevated even after the completion of treatment and the removal of the appliances. This highlights the necessity of implementing enhanced oral hygiene control measures and early preventive intervention.