Researchers and clinicians are increasingly examining oral health as a significant factor in wider systemic disease, with emerging evidence linking gum disease and chronic oral infections to cardiovascular disease, diabetes, stroke, arthritis and cognitive decline.

The growing body of research is also challenging the longstanding separation between dentistry and mainstream medicine, a divide rooted in the historical development of dentistry as a trade distinct from clinical medicine.

While dentists and physicians continue to train and operate through separate professional systems in many countries, including the United Kingdom, scientists say the biological relationship between oral health and the rest of the body is becoming more difficult to ignore.Steve Kerrigan, professor of precision therapeutics at RCSI University of Medicine and Health Sciences in Dublin, said the mouth functions as a direct pathway into the body’s circulatory and respiratory systems.

The human mouth hosts roughly 700 bacterial species, many of which are harmless under normal conditions but can become problematic when oral hygiene deteriorates.Gum disease remains one of the most common chronic inflammatory conditions globally. In the UK, around half of adults are estimated to experience some form of the disease.

Gingivitis, the early and reversible stage, is typically identified through bleeding during brushing or flossing. Periodontitis, a more advanced form, involves inflammation severe enough to detach teeth from the gums and is considered irreversible.“Gum disease is now classed as a chronic inflammatory condition in its own right,” Kerrigan said, comparing it to illnesses such as asthma, chronic obstructive pulmonary disease and Crohn’s disease.

Research into cardiovascular complications has become one of the most developed areas in the field of oral-systemic health. According to Kerrigan, several studies have shown that a large proportion of patients with cardiovascular disease also exhibit gum disease, although scientists continue to investigate whether oral disease directly causes cardiovascular conditions or acts alongside broader health factors.

One major focus is atherosclerosis, a condition in which cholesterol, fat and calcium accumulate on artery walls and restrict blood flow. Researchers have identified oral bacteria within atherosclerotic plaques, raising questions about whether bacteria from diseased gums contribute directly to plaque formation or become embedded after arterial damage has already occurred.

Scientists have also examined the role of oral bacteria in clot formation. Kerrigan said bacteria entering the bloodstream through bleeding gums or untreated dental infections can interact with platelets, the blood components responsible for clotting. That interaction may trigger the formation of clots capable of obstructing blood vessels.

“When these bacteria bind to platelets, it causes them to stick together the exact same way as when you cut yourself,” Kerrigan said. He added that clots reaching vessels in the brain may contribute to transient ischemic attacks or strokes, while clots affecting coronary circulation can increase heart attack risks.The same bacterial mechanisms have also been associated with infective endocarditis, a potentially serious condition involving inflammation of the heart’s inner lining and valves.

Patients with replacement heart valves have long received preventative antibiotics before invasive dental procedures because oral infections are already recognised as a source of bloodstream infection.Diabetes has emerged as another area where oral health appears closely connected to wider metabolic function.

Researchers increasingly describe the relationship as bidirectional. Chronic gum inflammation may interfere with blood sugar regulation, while persistently elevated glucose levels in diabetic patients can increase vulnerability to gum disease.A 2025 study cited by researchers found that patients undergoing root canal treatment experienced reductions in blood sugar, cholesterol and fatty acid levels after infected dental pulp was removed and sealed.

The findings suggested that treatment of severe dental infection could have broader metabolic benefits beyond preserving teeth.Kerrigan said mortality risks are significantly higher among patients who experience both diabetes and advanced gum disease compared with diabetic patients without severe periodontal problems.

Researchers are also investigating potential links between oral inflammation and degenerative or inflammatory conditions affecting other parts of the body. Studies referenced by Professor Kang found statistical associations between gum disease and worsening arthritis symptoms, particularly among patients with arthritic knees.

Kang said poor oral health can also affect psychological wellbeing and social behaviour. Pain, visible dental deterioration and chronic inflammation may reduce confidence and increase social withdrawal, while medications used to manage broader health conditions can reduce saliva production and further damage oral health.“Everything is interlinked,” Kang said.Researchers caution, however, that many findings remain based on population-level statistical analysis rather than direct prediction for individuals.

Experts stress that the existence of associations between oral disease and other illnesses does not mean isolated symptoms necessarily indicate severe future illness.“It does not apply to individuals,” Kang said, adding that occasional bleeding while brushing should not automatically be interpreted as evidence of future dementia or major disease.

The debate over oral health is unfolding amid mounting concerns over access to dental care, particularly in the UK’s National Health Service system. The government’s most recent oral health survey, published in 2021, found that around one-quarter of adults with natural teeth reported damaged, cracked or broken teeth, fillings or crowns.

At the same time, shortages of NHS dental appointments have led to reports of patients delaying treatment, self-medicating or attempting to remove damaged teeth themselves.Researchers say tooth loss may also alter the mouth’s microbiome, potentially affecting digestion and wider biological processes.

Kerrigan noted that oral bacteria play a role in the early stages of digestion, making long-term disruption to the oral environment a broader health concern.Dental specialists continue to emphasise basic preventive measures as the most effective strategy for reducing risks associated with oral disease.

Regular brushing, flossing and limiting sugar intake remain central recommendations.Kerrigan said electric toothbrushes with rotating heads may improve plaque removal compared with manual brushing. He also warned that frequent snacking on sugary foods can increase bacterial growth and accelerate gum and tooth damage.

Scientists say oral health should be viewed as part of broader preventive healthcare rather than as an isolated cosmetic issue.

Researchers note that individuals maintaining strong overall health habits often also demonstrate better oral hygiene practices, reflecting what they describe as an increasingly interconnected understanding of human health.