According to the British Heart Foundation as of early 2023, there are about 7.6 million people in the UK living with heart and circulatory disease. Of that around 4 million are men and 3.6 million women. Further, it states that heart and circulatory disease causes around a quarter of all deaths in the UK, which sums up to 460 each day. People with coronary heart disease or those who have had a heart attack are at a higher risk of having a stroke.There is evidence that mental health disorders such as depression and anxiety can develop when people suffer from heart conditions. As oral health issues such as cavities and tooth decay can lead to periodontal disease it in turn leads to increased risk of heart disease, it is important to maintain good oral health with good oral hygiene habits, to reduce this potential risk.

Try a search on Google Scholar. You'll get much more out of it than here.

Definitely there is association of dental health and heart disease as proved by research article . studies also showed that there is increased risk of infective endocarditis in whom dental caries are present so oral hygiene is recommended particularly dental infection before going to major valvular surgeries

Dental implant / root canal and poor hygienic condition of mouth lead to various chronic disorders including cardiovascular system, immunology, metabolic disorders

The relationship between oral infections and cardiovascular disease is well known, particularly with respect to orally derived bacteraemia as a source of organisms that infect damaged heart valves causing bacterial endocarditis.

Recently, evidence has emerged relating periodontal infections to coronary artery disease and stroke.Infective endocarditis (IE) is a microbial infection of a native or prosthetic cardiac valve or surrounding cardiac tissue. It may be caused by a variety of microorganisms, including bacteria, fungi, rickettsia, or chlamydia. Recent evidence linking severe, generalized periodontitis with coronary artery disease, suggests that the periodontics must be prepared to provide safe yet effective therapy to patients

with various types of heart condition. Dentists may provide dental care for patients with any of these disorders, most often they are called upon to manage patients at risk of IE. Dental procedures that involve manipulation of soft tissue and result in bleeding can produce transient bacteraemia.

Heart disease can affect oral health through various mechanisms, including altering blood flow, which can influence tissue healing and susceptibility to infections. An innovative response to this problem is the use of essential oil-laden nanoparticles, which provide delayed release . These nanoparticles can be used to treat or prevent oral conditions, having the ability to gradually release active ingredients directly into the affected area, ensuring a more effective and focused therapy. This is a promising field that combines nanotechnology with phytotherapy to improve oral health in patients with cardiovascular disease.

Nanotechnology may revolutionised the treatment for oral health issues in future apart from routine oral care

Assuming that one excludes various drugs such as cocaine, then the answer is cigarette smoking--in my opinion.