Relevance. Recent data from the World Health Organization highlight the high global prevalence of periodontal diseases. Among middle-aged adults in European countries, the prevalence ranges from 50% to 76%, while in Russia it reaches 86.2% in this group and approaches 100% by the age of 60–65. The diagnosis and prognosis of chronic periodontitis remain pressing challenges in clinical periodontology. While periodontal diseases have multifactorial etiology, microbial factors are primary. In particular, bacteria of the red complex – Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola – are considered key contributors to the progression of inflammation and tissue destruction in the periodontium. Objective. To detect and quantify red complex bacteria in patients with varying severity of chronic periodontitis.

Materials and methods. The study included 126 patients diagnosed with chronic periodontitis, categorized as mild (n = 39), moderate (n = 42), and severe (n = 45). A control group consisted of 39 periodontally healthy individuals. Subgingival plaque samples (from periodontal pockets in patients and from gingival sulci in controls) were analyzed using real-time polymerase chain reaction (PCR) on a DT-96 thermal cycler (DNA-Technology, Russia) with the ParodontoScreen diagnostic kit.

Results. The severity of periodontitis strongly correlated with the presence of P. gingivalis, T. forsythia and T. denticola, with correlation coefficients of 0.997, 0.929, and 0.888, respectively (p < 0.05). The number of genomic equivalents of these microorganisms also correlated with disease severity, with coefficients of 0.948, 0.984, and 0.889, respectively (p < 0.05).

Conclusion. The study confirms the significant role of red complex bacteria in the pathogenesis and progression of chronic periodontitis, supporting their relevance for diagnostic and prognostic applications in periodontal care.

Relevance. Early diagnosis of dental caries plays a key role in preventing periodontal diseases and supporting overall oral health. One promising approach for detecting pathological changes in dental tissues is electrical impedance spectroscopy (EIS), based on analysis of their frequency-dependent impedance characteristics.

Objective. To develop a methodology that applies impedance spectroscopy for the quantitative assessment of tissue changes in molars at varying depths of carious lesions.

Materials and methods. The study was conducted in vitro on 15 intact molars. Complex impedance was measured using an E7-20 impedance analyzer operating in the frequency range up to 1 MHz. Measurements were performed in the same region of each tooth before and after artificial demineralization.

Results. Enamel demineralization was found to affect the frequency-dependent impedance characteristics of molars in vitro. An equivalent electrical circuit was proposed to model the electrical processes in individual dental tissues. Experimental data, together with numerical simulations based on the equivalent circuit, enabled determination of circuit parameters before and after demineralization. The results indicate that the observed changes in impedance spectra are attributable to alterations in the resistive and capacitive properties of enamel, while the parameters of dentin remained unaffected. These changes can be explained by increased enamel porosity resulting from demineralization.

Conclusion. Analysis of frequency-dependent impedance characteristics and equivalent circuit parameters provides a means of identifying which dental tissues have undergone changes. These findings support the potential of impedance spectroscopy as a diagnostic tool for detecting early enamel demineralization.