This article provides a systematic review of studies on the composition of leech saliva secretions, the method of hirudotherapy, and the results of hirudotherapy in complex treatment. The following databases were used to search for the study: Scopus, Web of Science, MedLine, and Global Health. When using known methods of treatment, there is often no stability of results, this is explained by the search for new drugs and methods for treating periodontitis. It is known that the secret of the salivary glands of the medical leech contains more than 100 biologically active substances. The therapeutic effect of hirudotherapy is associated with the mechanical discharge of blood flow and the action of a complex salivary gland secretion of a medical leech. The molecules that exist in leech saliva and are the most studied to date include active substances such as hyaluronidase, hirudin, Kalin, destabilase, bdellins, histamine-like substances, hirustazine, factor XA inhibitor, and collagenase. It is scientifically proven that hirudotherapy leads to a significant improvement in the clinical condition of periodontal tissues, is simple, accessible, and can be recommended for use in the practice of periodontists.

This article reviews research data on the etiology, pathogenesis, and features of inflammatory periodontal diseases, the possibilities of using hirudotherapy to treat this group of diseases, and the mechanisms of action of this method. The literature search was conducted using the databases Scopus, Web of Science, MedLine, and Global Health. The mechanisms by which medical leeches influence the human body were analyzed. It is known that the progression of inflammatory periodontal diseases depends on risk factors such as age, smoking, gender, socio-economic factors, and some systemic diseases. The main features of chronic and acute periodontitis are periodontal pockets accompanying the loss of bone mass and attachment of the tooth to the alveolar process, which occur unevenly throughout the dentition. The decisive factor in inflammatory periodontal diseases is the presence of microorganisms. Hirudotherapy is a treatment method using the medical leech Hirudo medicinalis. In their secretion, leeches have more than 20 bioactive molecules with various effects. Their therapeutic mechanisms include six subtypes: a decrease in the content of cellular elements and neutrophils in mixed saliva, normalization of the microflora of the periodontal pocket, and an increase in the number of lactobacilli. The treatment method using leeches leads to a decrease in the depth of the periodontal pockets, normalization of the periodontal index, and tooth mobility. Hirudotherapy leads to a noticeable improvement in the clinical condition of periodontal tissues, is convenient to perform, affordable, and can be recommended for use in the practice of periodontists.