People who lose two or more teeth during middle age may be more likely to develop heart disease, scientists have found.
A study of nearly 61,000 adults aged between 45 and 69 showed those who lost two or more teeth had a higher chance of developing coronary heart disease than those who didn't lose any teeth.
Heart disease risk increased by almost a quarter among adults who had 25-32 natural teeth at the beginning of the study - most adults have 32 teeth - but lost two or more.
People's risk had still increased after researchers took into account their diet, level of physical activity, body weight, hypertension and other risk factors.
Losing only one tooth during the study was not associated with a higher risk of the disease but those who already had fewer than 17 natural teeth at the beginning of the study were 25 per cent more likely to develop it.
The researchers did not suggest how tooth loss and heart disease were linked, but experts have said in the past that bacteria could travel from infections in the mouth into the bloodstream and cause inflammation in blood vessels, which is associated with heart disease.
Coronary heart disease is a common killer in the UK and accounts for 22 per cent of all premature deaths, while in the US it kills 370,000 people every year. The NHS says most cases are preventable.
It is caused by a build-up of fatty deposits in the arteries, which restricts blood flow to the heart and can cause heart attacks.
People at higher risk of developing coronary heart disease include smokers and those with high cholesterol, high blood pressure or diabetes.
Links have been made between the condition and dental health in the past; tooth loss is a symptom of poor oral health and, this study suggests, an indicator of a higher risk of heart disease. The findings were presented at an American Heart Association event last month.
Anyone who lost two or more teeth - regardless of how many they had at the start - had a 16 per cent higher risk, but the risk among those who had 25-32 teeth was 23 per cent higher than those who did not lose any teeth.
Researcher Dr Lu Qi of Tulane University in New Orleans told Reuters: "In addition to other established associations between dental health and risk of disease, our findings suggest that middle-aged adults who have lost two or more teeth in the recent past could be at increased risk for cardiovascular disease.
"That's regardless of the number of natural teeth a person has as a middle-aged adult, or whether they have traditional risk factors for cardiovascular disease, such as poor diet or high blood pressure."
The study collected two sets of data beginning in 1986 and 1992, counting the number of teeth in women in the Nurses' Health Study (NHS) and men from the Health Professionals Follow-Up Study (HPFS), both in the United States.
All of the 60,967 participants were middle-aged - between 45 and 69 - at the start of the study and none of them had heart disease.
"The relation between dental health such as tooth loss and cardiovascular risk remains unclear," Dr Qi added.
The research, which Dr Qi presented at the 2018 Epidemiology and Prevention, Lifestyle and Cardiometabolic Health Scientific Sessions in New Orleans in March, suggests that tooth loss was related to inflammation and bad changes to the diet, which could be indicators of a future cardiovascular risk increase.
Dr Russell Luepker, a spokesman for American Heart Association, suggested it was important to consider social factors as well.
"We all get cavities and if you want to save teeth, you want to have good dental insurance and many people don't. So it's good to brush your teeth and it's good to have dental insurance," he told Reuters.