Men with a history of bone loss due to periodontitis run a higher risk of having a stroke, according to a study in the Annals of Neurology (May 28, 2009).
The potential role of periodontitis in the risk of cardiovascular disease has received much attention in the past decade, and evidence of an association between periodontitis and cerebrovascular disease, especially ischemic stroke, has been stronger compared to other types of cardiovascular disease, the study authors noted.
Although the link has been reported before, their research examined the clinical measures of periodontitis as opposed to self-reports or other assessments not involving periodontal probing, lead study author Thomas Dietrich, D.M.D., of the University of Birmingham School of Dentistry said.
The researchers analyzed data from 1,137 men in the Veterans Affairs Normative Aging Study, an ongoing study that began in the 1960s with healthy volunteers from the greater Boston area. Participants underwent medical and dental exams every three years for an average of 24 years.
A trained periodontist conducted the dental exams, including full mouth radiographs and periodontal probing at each tooth. Cerebrovascular disease was defined as a stroke or transient ischemic attack.
Dr. Dietrich and his colleagues evaluated the incidence of cerebrovascular events in relation to mean radiographic alveolar bone loss (a measure of periodontitis history) and cumulative periodontal probing depth (a measure of current periodontal inflammation).
Bone loss key
Overall, 80 incident cases of cerebrovascular disease occurred during a combined 27,506 person-years, and periodontal bone loss was "significantly associated" with an increased hazard rate of cerebrovascular disease, according to the researchers. They found a stronger effect among men younger than 65 compared to older men.
In comparison, periodontal probing depth was not associated with a significantly increased rate of cerebrovascular disease.
The exact mechanism of the association is unclear, said Dr. Dietrich, noting that both causal and noncausal factors may explain it.
There could be direct or indirect effects of the periodontal infection and inflammatory response, or some people may have an increased proinflammatory susceptibility that could contribute to both cerebrovascular disease and periodontal disease, the authors wrote. Current epidemiologic studies are not able to differentiate between these causal and noncausal pathways, even with perfect control of all established cardiovascular risk factors.
And why was periodontal bone loss significantly associated with an increased hazard rate of cerebrovascular disease, while periodontal probing depth was not?
"This is more consistent with a noncausal mechanism, since treatment of periodontitis or tooth loss would not affect the underlying susceptibility to inflammatory disease," Dr. Dietrich said.
A significant link was found between history of periodontitis as measured by alveolar bone loss and incidence of cerebrovascular disease in men, independent of established cardiovascular risk factors, the authors noted. Furthermore, they found evidence for a stronger association between periodontal bone loss and incidence of cerebrovascular disease among younger men.
"Even if this association was predominantly noncausal, periodontitis could be an important marker of risk for cerebrovascular disease, given its relatively high prevalence and the strength of the association," they concluded.
Large epidemiologic studies using molecular and genetic approaches in various populations are necessary to determine the strength of the association between periodontitis and cerebrovascular disease and to elucidate its biologic basis, they added.