The oral cavity contains a complex and dynamic microbial ecosystem that plays a central role in maintaining both local and systemic homeostasis. Emerging evidence indicates that disturbances in oral microbial communities-including genetic and functional diversity within species-are associated not only with oral diseases but may also contribute to the development and progression of systemic diseases. This narrative review summarises the current state of knowledge on bidirectional interactions between oral microbial communities and major organ systems. A comprehensive search of PubMed/MEDLINE, Web of Science, Scopus, and Cochrane databases was conducted for studies published between 2019 and 2025, prioritising systematic reviews, meta-analyses, and high-quality mechanistic studies. Ultimately, 40 articles were included in the narrative synthesis. The results provide clear evidence of an association between oral dysbiosis and cardiovascular disease (CVD), type 2 diabetes mellitus (T2DM), chronic respiratory infections, and adverse pregnancy outcomes (APOs). Recent data also suggest links with neurodegenerative disorders, chronic kidney disease (CKD), autoimmune diseases, and cancer. Proposed mechanisms include transient or persistent bacteraemia, systemic inflammation caused by microbial metabolites and endotoxins, disruption of immune homeostasis, molecular mimicry, and modulation of host metabolic pathways. Despite growing evidence linking oral microbial communities to systemic health, most findings are based on observational studies, and causal relationships remain to be established through longitudinal and interventional research. Understanding the connection between the mouth and the body highlights the potential for targeting oral microbial activity, virulence factors, and host inflammatory responses in disease prevention and treatment.

Burning mouth syndrome (BMS) and oral lichen planus (OLP) are two chronic oral diseases/disorders that continue to pose a challenge for conventional diagnosis and treatment. Both diseases do not occur in isolation but rather appear to reflect a broader interplay of psychological, neurological, endocrine, and immunological factors, i.e., complex disorders in interconnected biological and psychological systems. In BMS, patients often suffer from persistent burning sensations without visible lesions, which may be related to altered pain processing, emotional stress, and dysregulation in the brain regions responsible for interoception and perception. Although OLP is primarily characterised by immune-mediated mucosal damage, it often has significant psychological comorbidity, particularly in the erosive form. Common features such as cortisol imbalance, disturbed cytokine patterns, and high levels of anxiety and depression suggest that these conditions may be due to overlapping systemic disorders. It is no longer sufficient to focus only on the visible lesions or symptom relief. Understanding these diseases/disorders through a more comprehensive psychoneuroendocrine immune system (PNEI) opens up new opportunities for early intervention, improved diagnostics, and more personalised therapeutic strategies that go beyond treating symptoms. Ultimately, these diseases/disorders require a more integrated and patient-centred approach, where understanding the whole system is as important as treating its individual parts.

Objectives: Temporomandibular disorders (TMDs) are common but often underrecognized and inadequately managed in primary healthcare, which may delay diagnosis and appropriate care. This study aimed to compare TMD-related knowledge, awareness, and clinical practices between dentists and physicians working in primary care and to identify factors associated with higher diagnostic confidence. Methods: A cross-sectional survey was conducted among dentists and physicians working in Croatian primary healthcare. TMD-related knowledge, clinical confidence, screening practices, and referral patterns were assessed using a structured questionnaire. Results: Dentists demonstrated significantly higher overall knowledge scores than physicians (15.6 ± 1.7 vs. 13.2 ± 4.1; p < 0.001), as well as greater diagnostic and therapeutic confidence (all p < 0.001). Routine TMD screening was reported by only 21.8% of participants, more frequently by dentists than physicians (36.1% vs. 8.2%; p < 0.001). Most respondents preferred referral rather than independent management. Regression analysis identified profession as the only independent predictor of higher TMD-related knowledge (p = 0.003). Insufficient knowledge, experience, and lack of confidence were the most reported barriers, particularly among physicians. Conclusions: The findings indicate clinically relevant gaps in TMD preparedness within primary healthcare, especially among physicians, despite frequent patient contact. Strengthening undergraduate and continuing education, promoting interdisciplinary training, and establishing clearer referral pathways may enhance early recognition and improve primary-level management of TMD.

Objective: This study compared the effect on tooth colour (colour change and whiteness) of two commercially available charcoal-coated toothbrushes with that of a conventional toothbrush. Materials and Methods: In this randomised, assessor-blinded, parallel-group study, forty-seven adults were randomised to Colgate 360° Charcoal (C360C, n = 15), Curasept Black Luxury (CBL, n = 17), or a conventional control brush (n = 15). All participants used a whitening toothpaste for 20 days, followed by a non-whitening toothpaste for 20 days. Tooth colour was measured spectrophotometrically at baseline and after 20 and 40 days, and the CIE76 (ΔE*_ab) and CIEDE2000 (ΔE₀₀) colour differences and the Whiteness Index for Dentistry (WID) were calculated. Satisfaction (visual analogue scale, VAS), psychosocial impact (PIDAQ), and adverse effects were also recorded. Results: The colour change from baseline to day 40 (ΔE₀₀, primary outcome) did not differ between the charcoal brushes and the control (mean difference, −0.29; 95% CI, −1.13 to 0.55 for C360C and −0.14; 95% CI, −1.07 to 0.79 for CBL). Small differences in L*, a*, and b* during the first phase were no longer statistically significant at day 40, and WID did not increase in any group. Satisfaction increased in all groups, including the control (p < 0.001), and self-reported adverse effects did not differ significantly between groups. Conclusions: No evidence was found that charcoal-coated toothbrushes whiten teeth more than a conventional toothbrush; given the small sample, equivalence cannot be inferred. The increase in satisfaction in all groups may reflect expectations and study participation rather than the type of toothbrush.