Periodontal disease is the most common disease in the world with 90% of the adult population affected to some lesser or greater extent. The microorganisms that can be found in the mouth would be considered a serious threat to health if found elsewhere in the body and yet most dental and health professionals still consider oral infection to be a localised issue.
“The incidence of periodontal infection exceeds 70% in the 30 – 44 age groups and 90% in the 55 – 64 age group. The prevalence and severity of periodontal infection will increase as the life expectancy of the population and retention of teeth increase.”
US National Institute of Health
However, a growing body of research evidence over the last couple of decades has linked periodontal (gum) disease to a wide variety of systemic diseases. In fact, The Research, Science and Therapy Committee of The American Academy of Periodontology lists over 40 such diseases including:
- Infective endocarditis (damaged heart valves)
- Cardiovascular diseases including coronary thrombosis, arteriosclerosis, ischaemic heart disease and strokes
- Diabetes and obesity
- Respiratory problems including pneumonia
- Pancreatic cancer
- Rheumatoid arthritis and
- Some behavioural issues.
Such is the link that a study conducted by the University Of Michigan School Of Dentistry has found an association between poor dental health and premature death from all causes. This is significant too because the pathogens involved in periodontal disease are communicable and can potentially be passed between family members and down through the generations.
It is accepted that oral microorganisms can be launched into the circulation in appreciable numbers during some dental procedures and for this reason patients deemed to be ‘at risk’ are required to have prophylactic antibiotics (‘antibiotic cover’) for some kinds of dental treatment. Further, it is widely accepted that considerable numbers of bacteria enter the circulation during everyday activities including chewing and tooth brushing and that this too may pose a health risk in some vulnerable people.
Individuals considered to be ‘at risk’ from systemic bacteraemia include those with a history of infective endocarditis, heart valve disorders, congenital heart diseases and cardiac myopathy. Experts differ as to whether people who have had an intra-synovial joint replacement should receive antibiotic prophylaxis to prevent infection affecting established prostheses with the American Association of Orthopaedic Surgeons in favour and other professional bodies considering it unnecessary.
So the fact that oral microbes enter the circulation posing a threat to general health is well established and yet still overlooked by many. The following explores just some of the research evidence linking periodontal disease to systemic illness and the possible mechanisms by which this occurs.
“Gum disease is a threat to your oral health. Research is also pointing to possible health effects of periodontal diseases that go well beyond your mouth.”
The National Institute of Dental and Craniofacial Research (NIDCR)
Gum health and heart disease
There is growing evidence that the presence of periodontal disease can be linked to the incidence of coronary heart disease. Gums infected with periodontal disease are toxic reservoirs of disease-causing bacteria. The bacteria are able to live and reproduce in periodontal pockets adjacent to the teeth, where the healthy tight contact between the supporting tissues and the tooth has been lost.
The lining of such pockets is inflamed and provides an easy entry point for any microbes present to enter the general circulation as recently demonstrated by Dr Mark Herzberg and fellow researchers at the University of Minnesota in Minneapolis. In particular the bacteria, Streptococcus sanguis, can enter the circulation causing blood clots that can block arteries and trigger heart attacks. The researchers found that rabbits injected with plaque demonstrated reduced blood flow to the heart within as little as 30 minutes.
“Severe periodontitis is the equivalent of about nine square inches of chronic wound around the teeth. It offers considerable opportunity over time for these bacteria to enter the blood.”
Professor Mark Herzberg DDS PhD, director of the study
In a study of veterans conducted by Dr. Walter Loesche of the University of Michigan, older men with heart disease were found to have more active periodontal disease and more missing teeth, and those with severe periodontal disease were 4.5 times more likely to have coronary heart disease than those with healthy gums. In the same study, the researchers also showed an inverse relationship between regular dental appointment attendance and the likelihood of having a stroke.
Analysis of the fatty plaques associated with heart attacks and strokes at the State University of New York at Buffalo found that these deposits contained the DNA of several periodontal microorganisms, and that total bacterial numbers appeared to be more important than any specific species.
Another study of 10,000 adults found that people with periodontal disease also have elevated blood levels of the blood-clotting factor fibrinogen which may lead to blocked coronary or cerebral arteries (heart attacks and strokes respectively).
In a six-year prospective study of over 44,000 male health professionals (many of whom were dentists) those who had a history of tooth loss and/or periodontal disease at the start of the study demonstrated an increased risk of coronary heart disease.
Another study found that young adults who had some periodontal bone loss were 50% more likely to have a coronary heart problem and that fatal heart disease was twice as common in those with gum disease.
The Department of Oral Biology, University of Florida at Gainesville looked at the ability of three periodontal pathogens to invade the endothelial cells lining the blood vessels and the smooth muscle of the coronary artery. They found that specific species demonstrated the ability to invade the coronary artery cells at significant levels. In particular, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were found to be two of the most aggressive offenders associated with periodontal disease.
“Our finding is important because it has proved there are live periodontal bacteria in human atherosclerotic tissue. Now we can begin to understand how these bacteria contribute to the disease process.”
Professor Ann Progulske-Fox, Oral Biology, University of Florida College of Dentistry
And Finnish research conducted by Pussinen et al at the Helsinki University Central Hospital which followed nearly 10,000 patients over 14 years showed that those with the worst periodontal disease at the outset of the study had a 25% increased risk of developing coronary heart disease, especially the younger men.
There are several mechanisms by which oral and systemic diseases may be related. One is that during the immune response to chronic periodontal infection, there are elevated quantities of white blood cells and a pseudo-hormone called C-reactive protein (CRP) is produced by the liver. It is this protein that causes inflammation of artery walls causing compromised blood flow in certain vulnerable organs and systems. In addition, pre-existing conditions can also be made worse by the inflammatory and infective agents produced in chronic periodontal disease.
Research at the University of North Carolina found elevated levels of C-reactive protein in heart-attack survivors with advanced periodontal disease. And further studies found that CRP levels were directly related to the severity of the periodontal disease.
A recent study published in The New England Journal of Medicine identified elevated CRP levels as a stronger predictor of heart attacks than elevated cholesterol levels, and recommended CRP screening be included for an accurate risk assessment of cardiovascular disease.
Continued in Health and Oral Health 2.