The Scottish study of more than 11,000 adults backs previous research linking gum disease with heart problems.
The researchers said more work is needed to confirm if poor oral health directly causes heart disease or is a marker of risk.
A charity added that oral hygiene was just one factor in good heart health.
It is known that inflammation in the body, including in the mouth and gums, has an important role in the build up of clogged arteries, which can lead to a heart attack.
But this is the first time that researchers have looked at whether the frequency of teeth brushing has any bearing on the risk of developing heart disease.
Data, published in the British Medical Journal, was collected on lifestyle behaviours, such as smoking, physical activity and oral health routines.
Participants were also asked how often they visited the dentist and how often they brushed their teeth.
Then nurses collected information on medical history and family history of heart disease, took blood pressure and blood samples.
Overall, six out of 10 people said they visited the dentist every six months and seven out 10 reported brushing their teeth twice a day.
Over the eight-year study there were 555 “cardiovascular events” such as heart attacks, 170 of which were fatal.
Taking into account factors that affect heart disease risk, such as social class, obesity, smoking and family history, the researchers found those who brushed less than twice a day had a 70% increased chance of developing the condition.
Those with poor oral hygiene also tested positive in blood samples for proteins which are suggestive of inflammation.