The Gut–Oral Axis: The Impact of Oral Dysbiosis on Systemic Inflammation and Chronic Diseases

Abstract

Introduction: The gut-oral axis has become an important connection showing how problems with oral bacteria can lead to inflammation in the body and long-term diseases. This study aimed to investigate the association between oral dysbiosis, systemic inflammatory markers, and the prevalence of chronic inflammatory conditions.

Methodology: This cross-sectional study was conducted over 12 months at Khyber College of Dentistry, Peshawar. A total of 126 patients with at least one chronic disease (type 2 diabetes, cardiovascular disease, rheumatoid arthritis, or inflammatory bowel disease) were enrolled. Oral health status was assessed using clinical indices and saliva samples for microbial analysis. Systemic inflammation was evaluated via hs-CRP, IL-6, and TNF-α levels. Statistical analyses included chi-square tests, Pearson correlation, and multivariate regression.

Results: Oral dysbiosis was present in 64.3% of participants. Dysbiosis was significantly associated with elevated hs-CRP (mean 5.8 ± 2.1 mg/L), IL-6 (14.6 ± 4.2 pg/mL), and TNF-α (18.1 ± 5.5 pg/mL) (p < 0.001). Patients with a low Shannon diversity index (<2.0) showed markedly higher systemic inflammation. Oral hygiene parameters such as plaque index (PI ≥ 2) and bleeding on probing were independent predictors of dysbiosis (p < 0.05). Strong associations were noted between oral dysbiosis and type 2 diabetes (p = 0.002) and cardiovascular disease (p = 0.005), with weaker but notable links to rheumatoid arthritis.

Conclusion: Oral dysbiosis is significantly correlated with systemic inflammation and appears to influence the burden of chronic disease. Improving oral microbial health may offer a novel approach for reducing systemic inflammation and managing chronic inflammatory disorders.