Oral Health and the Salivary Microbiome in Blood Pressure Regulation: A Narrative Review

Hypertension remains the leading modifiable contributor to cardiovascular morbidity and mortality worldwide, yet blood pressure control rates remain suboptimal despite effective pharmacotherapy and lifestyle interventions. In parallel, oral diseases—particularly gingivitis and periodontitis—are highly prevalent chronic inflammatory conditions that share social and behavioural risk factors with hypertension and may also contribute to blood pressure elevation through biologically plausible pathways. Over the last decade, the oral–systemic paradigm has expanded from epidemiologic associations to mechanistic models implicating immune activation, endothelial dysfunction, oxidative stress, and microbiome-driven metabolic signalling. A distinctive and clinically relevant pathway is the enterosalivary nitrate–nitrite–nitric oxide axis, which relies on nitrate-reducing oral bacteria to support nitric oxide bioavailability and vascular homeostasis. Disruption of these bacterial communities—through antiseptic mouthwashes, dysbiosis, or periodontal inflammation—has been linked to altered nitrite generation and modest but measurable increases in blood pressure in experimental and clinical settings. In addition, high-throughput sequencing studies increasingly suggest that salivary microbiome signatures and functional potential differ between normotensive and hypertensive individuals, raising the possibility that salivary profiling may contribute to hypertension risk stratification and personalised prevention strategies. This narrative review synthesises evidence from observational studies, meta-analyses, Mendelian-randomisation-informed frameworks, interventional periodontal trials, and microbiome-focused investigations to clarify current knowledge on the oral health–microbiome–blood pressure nexus. We highlight methodological considerations in salivary microbiome research, discuss translational implications for dental and medical practice, and propose research priorities to establish causality and identify actionable interventions.