The researchers finds the mouths of those who flossed had significantly less bacteria -- the cause of periodontal disease -- an infection caused by a build-up of a sticky, colorless film constantly forming on teeth known as bacterial plaque.

The researchers compared 51 sets of twins between the ages of 12 and 32. The only difference between the groups was that flossing was added to a regimen of daily brushing with a manual toothbrush and toothpaste.

"This study illustrates the impact flossing can have on oral health. The twins experimental model is a powerful tool to help sort out genetic and environmental factors that often confound the interpretation of treatment studies," Dr. Kenneth Kornman, editor of Periodontology, said in a statement.

"Twins tend to share the same or similar environmental factors such as dietary habits, health and life practices, as well as genetics. In this case, the only difference was flossing, and the outcome was significant. Flossing may significantly reduce the amount of bad bacteria in the mouth."

The findings are published in the journal Periodontology.