People who do not brush their teeth twice a day have an increased risk of developing heart disease, the results of a new study indicate.

Over the last two decades there has been increased interest in links between heart problems and gum disease. While it has been established that inflammation in the body, including in the mouth and gums, plays an important role in the build up of clogged arteries, this is the first study to investigate whether the number of times individuals brush their teeth has any bearing on the risk of developing heart disease.

Researchers from University College London looked at the lifestyle behaviours of over 11,000 Scottish adults. These behaviours included smoking, exercise and oral hygiene routines.

All of the participants were asked whether they visited the dentist at least once every six months, every one to two years, or rarely/never. They were also asked how often they brushed their teeth - twice a day, once a day or less than once a day.

On a separate visit, nurses collected information on the medical and family history of the participants. This included details of heart disease and blood pressure. Blood samples were taken and these enabled the researchers to determine levels of inflammation that were present in the body. The data gathered from the interviews were linked to hospital admissions and deaths in Scotland until December 2007.

The study found that oral health routines were generally good, with six out of ten (62%) participants saying they visited the dentist every six months and seven out of ten (71%) saying that they brushed their teeth twice a day.

Once the results were adjusted for established heart risk factors such as obesity, smoking and family history of heart disease, the researchers found that participants who reported less frequent toothbrushing had a 70% extra risk of heart disease compared to individuals who brushed their teeth twice a day.

However, the team emphasised that the overall risk remained quite low.

"Our results confirmed and further strengthened the suggested association between oral hygiene and the risk of cardiovascular disease. Future experimental studies will be needed to confirm whether the observed association between oral health behaviour and cardiovascular disease is in fact causal or merely a risk marker," said lead researcher, Prof Richard Watt.

Details of these findings are published in the British Medical Journal.

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