A recent study suggests a causal relationship between oral pathology-that is, gingivitis and periodontitis-and stroke. Periodontitis is the leading cause of tooth loss in the United States; the disease may affect nearly 50% of Americans older than 65 years. The pockets of infection that surround the teeth and penetrate into surrounding tissues function as chronic abscesses. The ongoing infection may seed the bloodstream with bacteria during flossing, toothbrushing, or professional cleaning.
How strong is the evidence linking oral bacterial infections with vascular disease?
A recent study suggests a causal relationship between oral pathology-that is, gingivitis and periodontitis-and stroke.1 Periodontitis is the leading cause of tooth loss in the United States; the disease may affect nearly 50% of Americans older than 65 years.2 The pockets of infection that surround the teeth and penetrate into surrounding tissues function as chronic abscesses. The ongoing infection may seed the bloodstream with bacteria during flossing, toothbrushing, or professional cleaning.
Some of the bacteria in the oral cavity are Gram-negative; they possess capsules that may stimulate pro-inflammatory cytokines, such as tumor necrosis factor and interleukins. Cytokines and ongoing inflammation have been linked to vascular disease.
One study found a direct correlation between gum disease and carotid plaques.2 A similar relationship between Chlamydia pneumoniae infection and vascular pathology has been suggested.1
A LINK BETWEEN ORAL INFLAMMATION AND STROKE
In a cohort of about 1000 "aging" men, periodontal disease was associated with a 1.5 times greater risk of coronary artery disease, a 1.9 times greater risk of fatal coronary disease, and a 2.8 times greater risk of stroke.3 In the National Health and Nutrition Examination Survey (NHANES), nearly 10,000 participants were assessed for periodontitis; the prevalence was 16.8%. In persons with periodontitis, the risk of stroke was 2.1 times higher than in those without periodontitis; however, no increase in coronary disease was found.4
The results of these 2 studies are corroborated by a summary of work in this area that includes a meta-analysis.5 Periodontal disease may be one of many risk factors for vascular disease, especially in the vascular bed of the CNS (possibly related to accelerated carotid disease).
WHAT ARE THE IMPLICATIONS FOR THERAPY?
Do the data regarding periodontal disease and vascular complications, particularly the increased risk of stroke, have therapeutic implications? The answer as of yet is no, but some preliminary observations should be made. Since periodontitis has also been implicated as a possible cause of preterm births and is both more common and severe in persons with diabetes, it will continue to evolve as a potential culprit for serious complications and disorders.1 The definition of periodontitis must be standardized: namely, is it a clinical diagnosis or should it be diagnosed by imaging? Finally, prospective studies are needed to demonstrate a decrease in vascular risk with regular, professional dental care in general and, more specifically, with care that targets gum disease.
Recently, an experimental first step in this direction was taken. In a cohort of 120 patents with severe periodontitis, 59 received "usual" care and 61 received "intensive" care (full-mouth removal of plaque with scaling and planing). Six months later, a significant correlation was found in the intensively treated group between a reduction in periodontal disease and an improvement in endothelial function.6 Prospective studies are on the horizon.
REFERENCES:1. Elkind MS, Cole JW. Do common infections cause stroke? Semin Neurol. 2006;26:88-99.
2. Engebretson SP, Lamster IB, Elkind MS, et al. Radiographic measures of chronic periodontitis and carotid artery plaque. Stroke. 2005;36:561-566.
3. Beck J, Garcia R, Heiss G, et al. Periodontal disease and cardiovascular disease. J Periodontol. 1996;67:1123-1137.
4. Brown LJ, Brunelle JA, Kingman A. Periodontal status in the United States, 1988-1991: prevalence, extent, and demographic variation. J Dent Res. 1996;75: 672-683.
5. Pihlstrom BL, Michalowicz BS, Johnson NW. Periodontal diseases. Lancet. 2005;366:1809-1820.
6. Tonetti MS, D'Aiuto F, Nibali L, et al. Treatment of periodontitis and endothelial function. N Engl J Med. 2007;356:911-920.