The more germs you have in your mouth, the more likely you are to have a heart attack, suggests new research that adds to a growing body of evidence linking oral hygiene with overall health.

The study compared heart attack victims to healthy volunteers and found the heart patients had higher numbers of all kinds of bacteria in their mouths.

Several studies have suggested there is a connection between bacteria that cause gum disease, or periodontal disease, and heart disease, but few studies have identified those bacteria.

Dr. Oelisoa Andriankaja and colleagues at the University at Buffalo were trying to find if any particular species of bacteria might be causing heart attacks.

While they narrowed down two oral pathogens that were associated with an increased risk of having a heart attack, they found that the total number of germs -- regardless of type -- was more important to heart health.

Results of the study are being presented at the International Association of Dental Research meeting in Miami.

"The message here is that even though some specific periodontal pathogens have been found to be associated with an increased risk of coronary heart disease, the total bacterial pathogenic burden is more important than the type of bacteria," said Andriankaja , now with the University of Puerto Rico's School of Dental Medicine.

"In other words, the total number of 'bugs' is more important than one single organism," she said.

The study involved 386 men and women between the ages of 35 and 69 who had suffered a heart attack. They were compared to 840 people free of heart trouble. Samples of dental plaque, where germs adhere, were collected from 12 sites in the gums of all participants.

The samples were analyzed for the presence of the six common types of periodontal bacteria, as well as the total number of bacteria.

The heart patients harboured more of each type of bacteria than the healthy volunteers, the analysis showed.

Two species, known as Tannerella Forsynthesis and Preventella Intermedia, had a statistically significant association with an increased risk of heart attack, as did a high number of different periodontal bacteria.

Doctors are not sure how germs in the mouth may be linked with heart attacks but it may be that bacteria set off general inflammation, which in turn causes blood to clot and lead to a heart attack.