Gum disease isn't just bad for your teeth - it can also cause serious illnesses, from heart disease to anaemia. Roger Dobson reports

The Government's recent instructions telling us how to brush our teeth properly met with derision; another example of the nanny state gone mad. But we should listen. It may not only help to save your teeth - it could save your life.

When Barbara Taylor and her team extracted the teeth of patients with gum disease, there was an extra benefit. Not only did the bad breath and bleeding gums vanish, but the risk of heart disease and stroke in the future went down too. Compounds in the blood associated with the two diseases dropped significantly after all the teeth of the 67 patients were removed. Levels of the same markers also dropped when other patients with less severe forms of the disease were shown how to clean their teeth properly.

"We have shown that treating severe gum disease reduces risk factors that have been associated with heart attacks and strokes," Dr Taylor says. Her findings are among the latest to suggest that good dental hygiene may lower the risk of a whole range of conditions.

Periodontitis and other gum diseases have now been linked to premature birth, low birth weight, higher sugar levels, diabetes, immune problems, anaemia, respiratory disease, liver and cholesterol problems and rheumatoid arthritis, as well as stroke and heart disease.

Gum problems, which affect more than half the adult population, usually begins with a build-up of plaque, a sticky coating made up of food and bacteria that can lead to irritation of the gums, bleeding and gingivitis. If this early stage disease is not treated, it can develop into periodontitis, where the gums swell, forming pockets around the teeth in which plaque collects. In its severe form, found in about one in five people, it triggers chronic inflammation and immune reactions resulting in a shrinking of the gum, bone and soft tissues. Eventually, teeth can become loose and may have to be removed.

Until relatively recently, loss of a tooth or two was thought to be pretty much the worst that could happen with gum disease. Not any more; researchers are increasingly findings that gum disease may increase the risk of other diseases or worsen existing symptoms.

One new finding comes from a Helsinki University study, based on patients followed for more than a decade. This showed that women with high levels of antibodies to the pathogen most strongly associated with periodontal disease were more than twice as likely to have a stroke.

Research at the University of New York shows that treating periodontal disease with scaling and root planing significantly lowers the levels of two inflammatory compounds associated with heart disease. Blood taken from patients with gum disease showed elevated levels of C-reactive protein (CRP) and fibrinogen, proteins associated with increased risk of heart disease and blood clotting.

Other compounds are thought to be responsible for higher rates of premature babies. Research at the University of Alabama is showing that gum infections trigger an increase in the levels of prostaglandin and other compounds that induce labour. The researchers were able to reduce premature birth by up to 84 per cent in women who received scaling and root planing when they were less than 35 weeks pregnant: "Scaling and root planing may significantly reduce a mother's chance of having a pre-term birth," they say.

At the Dental School of the University of Itajai in Brazil, scientists have shown that gum disease is associated with small babies. "Periodontal disease in normal pregnant women older than 25 is associated with a reduction in the infant birth weight. This is new evidence on the relationship between periodontal disease and birth weight," they say.

Rheumatoid arthritis is yet another health problem that may have links with gum disease. One Australian study reported that patients with rheumatoid arthritis were more than twice as likely to have severe gum disease. It's not known yet whether gum disease may be one of the triggers for arthritis, but some scientists believe that infection may play a part in some cases.

Similar links emerge with diabetes. A study by a team from the US National Institute of Diabetes and Kidney Disease has shown an association between the severity of periodontal disease and mortality in diabetes patients. The 11-year study of patients with type 2 diabetes found that periodontal disease was a predictor of death from heart disease and diabetic nephropathy. After taking into account the duration of diabetes, blood pressure, tobacco use and other factors, it found that those with severe periodontal illness had 3.2 times the risk of cardiorenal mortality.

Exactly how gum disease is involved in such a diverse group of conditions is not known. One theory is that periodontal bacteria get into the bloodstream and travel to major organs to begin new infections. Compounds involved in inflammation may play a part, and bacteria that cause gum disease may increase the rate at which arteries become blocked.

With heart disease and stroke, one theory is that bacteria may enter the bloodstream and activate the immune system, resulting in the artery walls becoming inflamed and narrowed. Another theory is that the bacteria attach themselves directly to the fatty deposits that are already present in the arteries, causing further narrowing.

The research by Dr Taylor at Sydney Dental Hospital involved analysing blood samples from people who'd had all their teeth extracted. It showed that levels of compounds involved in inflammation and clotting had gone down. "There were significant changes in nine markers," Taylor says. "This is an important finding, but the problem is that removing all a patient's teeth is not, of course, a practical public health strategy. It's like cutting your foot off to get rid of a pain in the big toe."

Her team have been using dental hygiene strategies on another group of people with moderate disease to see whether teeth cleaning has a similar effect. The investigation continues, and it looks promising. "I looked at the data on Friday and we are approaching a significant difference," Taylor says. "What we are seeing is consistent with our other findings."

Firm results are not expected for some time, but if they continue on the present course, they may provide the best evidence yet that visiting the dentist could save your life.

A guide to oral hygiene

* Periodontal or gum disease is the most common chronic infection

* Gingivitis is the milder form of gum disease, where the gums swell and bleed

* Periodontitis is the more severe form, damaging the bone and tissue that holds teeth in place

* Bleeding gums after brushing is often the first sign of gum disease

* Other symptoms include bad breath, swollen and tender gums, receding gums, new gaps between the teeth and loose teeth

* Smoking, genes, some medications and lowered immunity increase the risk of gum disease

* Brushing and flossing - and especially professional cleaning - can reduce the chances of getting gum disease