“I don’t need to floss” is a sentence my dentist never used to hear – not until recently, when the latest Dietary Guidelines for Americans stopped recommending it. Now, lots of his patients are telling him they’ve stopped. Despite the NHS advising daily flossing – and almost all dentists being fans of interdental cleaning – an investigation by Associated Press found “little proof that flossing works”.
But how can it not be good for you? Between our teeth are interdental sites coated in dental plaque. Plaque is a layer of bacteria mixed with organic matter that coats teeth and causes gum inflammation (gingivitis) and tooth decay. Early warning signs include bleeding gums. Toothbrushes get rid of plaque from other surfaces, but are not so good between teeth. Surely floss can reach the parts that brushes can’t?
The lack of good research emerged in a 2011 systematic review by the Cochrane Oral Health Group. Its summary of results from 12 studies found only weak evidence that flossing (plus brushing) reduces bleeding from gums, and none for plaque reduction. But good studies are hard to do. The quality of flossing varies. One study showed that professional flossing five times a week can reduce tooth decay – a result not seen in any studies of self-flossing – so it’s clearly a skill. Experts advise moving the floss, held in a C shape, away from the gum in an up-and-down motion.
However, the Cochrane paper actually said that, although the research was poor, the benefits of flossing probably outweighed any risks. Bleeding gums is a risk factor in developing chronic gum disease than can destroy the bone underneath. Professor Damien Walmsley, a scientific adviser for the British Dental Association, says that brushing teeth twice a day with a fluoride toothpaste and only occasionally eating sugar treats after meals is the best way to prevent tooth decay. He believes flossing is of little value and that small interdental brushes are better at cleaning the gaps between teeth.
No one, however, is arguing that flossing isn’t useful for dislodging unsightly food stuck between teeth. My own dentist, Richard Travers, thinks we can drop the daily enslavement and reduce flossing to twice a week, increasing if our gums start bleeding. His gut feeling, from what he sees, is that both flossing and interdental brushes are useful. And, in a recent feature in the British Dental Journal, senior dentists including Phil Ower, the president of the British Society of Periodontology, announced that they still floss their own teeth.