Can Flossing Teeth Foil Heart Disease?
The Lancet Volume 360 Issue 9327, 2002 Page 147
*The concept of a link between oral health and heart health--and the idea that flossing and other dental interventions may one day help thwart heart disease--holds special appeal because, enthuses microbiologist and molecular geneticist Paula Fives-Taylor (University of Vermont, Burlington, VT, USA), "periodontitis is something we can cure. It's not just a lifestyle change, which is most of what we're told to do for heart disease now. I believe there's a connection and that the data are getting stronger. And if the association holds, then curing periodontal disease could have a major public health impact."
Data supporting an association were presented at the 12th International Conference on Periodontal Research (University of North Carolina School of Dentistry, Chapel Hill, NC, USA; June 5-12). Periodontist and biochemist Steven Offenbacher and colleagues showed that periodontal treatment improves endothelial function, "which has implications for the heart", says Offenbacher, who has also shown that periodontitis is associated with increased carotid artery intima-media thickness, thereby possibly playing a role in atheroma formation (Arterioscler Thromb Vasc Biol 2001; 21: 1816-22). In ongoing studies, "we're also seeing decreases [with periodontal treatment] of vascular markers of stress, such as C-reactive protein."
*Fives-Taylor notes that "risk factors for both diseases are almost identical: age, male gender, smoking, increases in plasma fibrinogen and white cells, and diabetes". Also, periodontal disease is a bacterial infection that, like heart disease, involves inflammatory processes; therefore, periodontal disease could be stimulating immune mediators that affect the heart. Others are looking at cause-and-effect: both conditions involve the same inflammatory mediators, and periodontal organisms--Chlamydia pneumoniae, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans--have also been found in atheromas.
Periodontist and immunologist Robert Genco (SUNY at Buffalo, Buffalo, NY, USA) is principal investigator for PAVE (Periodontal Intervention in Cardiovascular Disease), a 27-month pilot trial scheduled to launch in September, 2002, with funding from the US National Institutes of Health. The trial aims to assess the effects of treating periodontal infection in high-risk patients with severe periodontal disease who have had a heart attack, vascular surgery, or coronary artery surgery, or who have 50% blockage in one or more arteries, explains Genco. PAVE will evaluate surrogate variables such as C-reactive protein concentrations, which have been shown to be reduced by periodontal disease treatment and might also affect cardiovascular event risk.
"We're taking an objective look at this", stresses Genco. "We have enough indication that there may be a relationship. The concept of infection playing a role in cardiovascular disease is gaining momentum, and although we have no definitive treatment trials yet, there's accumulating in-vitro, animal model, and epidemiological evidence for the role of infection, including periodontal infection."
Periodontologist and epidemiologist Philippe Hujoel (University of Washington, Seattle, WA, USA) suggests that although infection and inflammation may be found in both periodontitis and heart disease, it is smoking that may link the two. "Studies must be done among never-smokers to see if there is really an association between the two diseases", says Hujoel. "It's the same for obesity research, where if you want to look at the adverse health effects of obesity, you should look at never-smokers because the effect of smoking is so overwhelming, it biases all findings."
Among never-smokers, an association between periodontal disease and any systemic disease has not been shown, says Hujoel, whose study of periodontitis and systemic disease associations in the presence of smoking will be published in the October, 2002, issue of Periodontology 2000. "Among smokers, periodontitis is associated with all the diseases that smoking causes . . . It even has an apparent protective effect in Parkinson's disease, just like smoking", he asserts. "If we want to try to explain why periodontitis is associated with systemic disease among smokers, we cannot pick and choose which diseases we're going to try to explain. The fact that periodontitis is associated with all diseases related to smoking is evidence that we cannot distinguish the effect of smoking on periodontal disease or on any systemic disease", he says, noting that "edentulous people are not at a lower risk for heart disease than people with periodontal disease".
Mark Ide, lecturer in periodontology and preventive dentistry at King's College, London, UK, agrees that the link "has been a bit hyped". His group has a study in press that measured surrogate markers of cardiovascular disease, including C-reactive protein and fibrinogen, in patients with moderate periodontal disease. Non-smokers did not have elevated values of inflammatory markers. And although "one simple course of treatment didn't eliminate all periodontal disease, it did calm things down a bit", he says. "But that didn't seem to change the levels of the circulating acute-phase proteins."
Nevertheless, speculates Ide, "there is a possibility that if you had some gum disease, some lung disease, and some heart disease, then maybe all of those things together have an additive effect". "One proposed mechanism is that when people chew, they create a bacteraemia and pump toxins into the circulation that then have a systemic effect that may cause promotion of atherogenesis and similar effects", he explains. "We looked at endotoxin levels during and after periodontal treatment [by pulling blood samples using an indwelling catheter] and found that with treatment, within a couple of hours, we see a significant elevation of circulating cytokines such as interleukin-6. It's as if the treatment itself and the bacteremia and toxins associated with treatment are sufficient to temporarily lift those things up. Even when people with gum disease chew, they can push endotoxins into their system. And so it may be that there is something going on."
So what should patients be told? "I think the biggest thing is to recognise, whether or not this association turns out to be the final answer isn't important, because you have nothing to lose by getting people to take care of their teeth", says Fives-Taylor.
Reprinted with permission from Elsevier Science (The Lancet, 2002, Vol. 360, p. 147.)
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