A report from the Associated Press has found that flossing has no real impact on dental hygiene and that it does not reduce the risk of tooth cavities and gum disease. In its latest Dietary Guidelines, published in 2015, the US Federal Government removed the recommendation for flossing without notice.
For decades, health authorities and dentist associations have promoted flossing, saying it could prevent cavities and other dental problems. The American Dental Association writes on its website people should floss once a day.
In order for a recommendation to be included in the Dietary Guidelines, it has to be based on robust scientific findings by law.
To make sure this was the case for flossing − which had been recommended by the federal authorities since 1979 − the Associated Press asked the US departments of Health and Human Services and Agriculture last year to submit evidence about the practice's beneficial effects. It followed up with written requests under the Freedom of Information Act.
The authorities responded by removing flossing from their guidelines. They also acknowledged in a letter that the effectiveness of flossing had not been sufficiently researched before it was recommended.
In the meantime, the Associated Press also reviewed 25 of the most rigorous studies conducted in the last decade about flossing. Most concluded that the evidence for flossing was either weak, unreliable or carry a potential for bias. Some used outdated methods, tested very small samples of people or were very short in duration − too short for dental diseases to develop.
To avoid gum disease and cavities, the most effective method remains to brush the teeth twice a day, cut back on sugar and visit the dentist regularly.