Study illuminates link between oral health and heart attack

Dental Tribune International

Thu. 9. October 2025

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TAMPERE, Finland: The long-standing relationship between oral bacteria and systemic disease has taken on new significance with recent advances in molecular medicine. As part of this trend, a groundbreaking study by Finnish researchers has found compelling evidence that bacteria commonly found in the mouth could play a causal role in heart attack. The research suggests that myocardial infarction may, in some cases, be triggered by infectious processes originating in oral biofilms.

In recent years, the link between oral health and general health has become an increasingly important focus of discussion in both academic and clinical contexts. Among these connections, the relationship between oral health and cardiovascular disease has been especially extensively studied. A study from 2024, for example, identified periodontal disease as a “non-traditional risk factor in the development of and progression of cardiovascular diseases”.

Building upon these scientific foundations, the findings of the new Finnish study indicate that the connection may be direct. The researchers discovered viridans streptococci—a group of bacteria typically associated with dental biofilm and infective endocarditis—within atherosclerotic plaques obtained from sudden cardiac death victims and vascular surgery patients.

The study analysed coronary plaques from 121 autopsy cases and endarterectomy samples from 96 surgical patients. Using advanced molecular techniques, the team found viridans streptococcal DNA in approximately 42% of both sample sets. These bacterial biofilms were embedded deep within the arterial deposits and evaded the body’s immune system, allowing chronic, low-grade infection to persist unnoticed.

Further investigation revealed that portions of the bacterial biofilm had detached and migrated towards the surface layer of the plaque—the fibrous cap that separates the deposit from the bloodstream. This cap is where ruptures often lead to fatal myocardial infarction. The dispersed bacteria were shown to trigger both innate and adaptive immune responses and thereby fuel inflammation.

The findings challenge long-held views of myocardial infarction as purely a metabolic disease, suggesting instead that chronic bacterial infection may contribute to the development of heart attack in some cases. Speaking in a Tampere University press release, lead author Prof. Pekka Karhunen, of the university’s Faculty of Medicine and Health Technology, explained the significance of the research: “Bacterial involvement in coronary artery disease has long been suspected, but direct and convincing evidence has been lacking. Our study demonstrated the presence of genetic material—DNA—from several oral bacteria inside atherosclerotic plaques.”

For dentistry, the implications are profound. As viridans streptococci are integral to dental biofilm formation, the study underscores the importance of maintaining rigorous oral hygiene and managing chronic dental infections—not only for oral health but potentially for reducing cardiovascular risk.

The study, titled “Viridans streptococcal biofilm evades immune detection and contributes to inflammation and rupture of atherosclerotic plaques” , was published online on 19 August 2025 in the Journal of the American Heart Association.