NEW YORK (Reuters Health) - Missing teeth, loss of bone around teeth and reduced periodontal health appear to be associated with an increased risk of ischemic stroke, the type caused by blood clots, Massachusetts-based researchers report in the Journal of Periodontology.

"Further studies need to be conducted to confirm this association," senior investigator Dr. Martha E. Nunn told Reuters Health, "but given our research, as well as other research in this area, I would advise anyone at risk for stroke to maintain good oral health as part of an overall strategy to insure good overall systemic health."

Several studies have suggested a relationship between periodontal (gum) disease and stroke. However, the connection is by no means clear.

To investigate further, Nunn and colleagues at Boston University studied the relationship between gum disease and history of stroke in individuals 60 years of age and older who had taken part in a US national survey which ended in 1994.

After adjustment for age and tobacco use, people who were completely edentulous (toothless), partially toothless and/or had significant clinical attachment loss were significantly more likely to have a history of stroke than those with teeth and no appreciable attachment loss.

The likelihood of having had a stroke was about twice as high in those with complete tooth loss or extensive gum disease as among those with good oral health.

The researchers point out that it is unclear "whether periodontal disease is an independent risk factor for stroke or a risk marker for the disease."

Nunn added that advice to take care of dental health in order to lower overall health risks is supported by results of another study, which showed that a single periodontal treatment, such as scaling, can lower levels of C-reactive protein, an inflammatory marker known to be associated with heart and vascular disease.

Chronic inflammation arising from dental disease has been implicated in the development of atherosclerosis or hardening of the arteries -- a key risk factor for stroke.