The theory is that flossing reduces the risk of tooth decay and gum problems because it prevents plaque buildup.
The plaque is a sticky layer of bacteria that feeds on the carbohydrates we eat. If left to grow, it eventually begins to damage the surface of the tooth, leading to painful cavities, which must be filled or which lead to tooth extraction, if they are widespread.
The plaque begins to form just after it has been removed, and if it is not removed it can produce gingivitis, a condition in which the gums swell and bleed easily. In a 26-year longitudinal study conducted in Norway, teeth found that were surrounded by inflamed gums were 46 times more likely to end up being lost than those with healthy gums.
We know that the brush cannot attack the plaque problem completely, because it is difficult to reach certain areas between the teeth. The original idea of flossing to achieve them is attributed to a New Orleans dentist named Levi Spear Partly, who recommended using silk for this purpose in 1815.
But not only do humans. Crab monkeys from the Prang Sam Yet Buddhist temple in Thailand take strands of human hair and wrap them in their fingers to get to those difficult corners their mouth.
There is plenty of evidence to suggest that flossing reduces plaque levels, but what evidence is there that it can recoup the risk of tooth decay and gingivitis? When you analyze the data carefully, the relationship is not as direct as one might think.
A study on flossing in children found that plaque can be reduced, but in adults it is not so easy to demonstrate.
A review, published in 2012 by the respected NGO of doctors, researchers and patients Cochrane Collaboration, compiled all the existing research in this matter and found only 12 experiments, most done in the United States, in which adults had been asked Randomly use the floss in addition to brushing teeth and others not.
And what they discovered did not impress them. Combining the results of the studies and reanalyzing them, they found a possible small reduction in plaque, but the evidence from the studies was rated weak and very unreliable.
“We are not able to affirm or refute that flossing, besides brushing, has a benefit,” they concluded. A reduction in plaque would suggest a reduction in caries in the long term, but there was no controlled study to check it (the longest lasted nine months). None had included an evaluation of the effect in terms of caries because more time would have been needed to observe a difference.
Hole in the literature
The findings of recent studies on gingivitis are more eloquent. Flossing helps reduce risk, though only by 8%. At least this is good news for flossing supporters, compared to a review in 2008 that found no benefit could be shown.
The idea is to reduce dental visits, not increase them.
But the quality of the evidence makes it difficult to come to any firm conclusions. The Cochrane review not only compares all available data but also evaluates the research according to the quality of the design and execution. And the verdict is that many studies do not measure up.
Although the research is very poor, it is the only thing we have in hand at the moment. So one could argue that if flossing is possibly good, what’s wrong with getting everyone to practice?
The reason could be at risk of getting hurt, something that has addressed some studies. In one of them, three of 39 people injured their gums during the experimental phase. Two months later, two of those three people were no longer in trouble. In another study, two people injured their gums improperly using a kind of automatic dental floss.