Tobacco-Induced Oral Dysbiosis and Microbial Shifts: A Narrative Review of Their Role in Systemic Inflammation and Disease.

The oral cavity is home to a diverse community of microbiota comprising bacteria, viruses, protozoa, and fungi. These microorganisms inhabit several oral niches and play a significant role in supporting both oral and systemic health. The fine balance between the microbial communities can be influenced by genetics and environmental factors, potentially leading to dysbiosis. Alterations in the oral microbiota have been implicated in periodontitis, chronic inflammation, and systemic disease. Tobacco has been identified as a major player in altering the oral microenvironment and disturbing the balance between potentially pathogenic and beneficial commensals. The resulting dysbiosis promotes inflammation and assists in the passage of pathogenic microorganisms into the blood system. This narrative review examines current evidence linking the use of tobacco with the dominance of pathogenic oral bacteria and a dysfunctional immune response. We explore how the chemicals and toxins in cigarettes promote a reduction in oxygen and cause changes in the abundance of anaerobic bacteria. After discussing the mechanistic pathways leading to periodontitis and the entry of microorganisms into the circulation, the review will interrogate previous studies and identify opportunities and priorities for future research.