Floss daily to prevent gum
disease and cavities is something we have been told for years.
However, there is little proof that flossing works.
The federal government,
dental organizations, and manufacturers of floss have pushed the
practice for decades. Dentists provide samples to their
patients. The American Dental Association says on its website
that, “Flossing is an essential part of taking care of your
teeth and gums.”
During 2017, the
Associated Press asked the departments of Health and Human
Services and Agriculture for flossing efficacy evidence, and
followed up with written requests under the Freedom of
Information Act.
During 2018, the
federal government issued its latest dietary guidelines and the
flossing recommendation had been removed, without notice. In a
letter to the AP, the government acknowledged the effectiveness
of flossing had never been researched, as required.
The AP reviewed
research conducted during the past ten years, focusing on twenty
five studies that generally compared the use of a toothbrush
with the combination of tooth-brushing and floss. The evidence
for flossing is “weak, very unreliable,” of “very low” quality,
and carries “a moderate to large potential for bias.” “The
majority of available studies fail to demonstrate that flossing
is generally effective in plaque removal,” according to one 2017
review. Another 2015 review cites “inconsistent/weak evidence”
for flossing and a “lack of efficacy.” A 2011 study did credit
floss with a slight reduction in gum inflammation, which can
sometimes develop over time into full-fledged gum disease.
However, the reviewers ranked the evidence as “very unreliable.”
A commentary in a dental magazine stated that any benefit would
be so minor it might not be noticed by users.
Two leading
professional groups, the American Dental Association and the
American Academy of Periodontology, for specialists in gum
disease and implants cited other studies as proof of their
claims that flossing prevents buildup of plaque, early gum
inflammation called gingivitis, and tooth decay. However, most
of these studies used outdated methods or tested few people.
Some lasted only two weeks, far too brief for a cavity or dental
disease to develop. One tested 25 people after only a single use
of floss. Such research, like the reviewed studies, focused on
warning signs like bleeding and inflammation, barely dealing
with gum disease or cavities.
The president of the
periodontists’ group, acknowledged the weak scientific evidence
and the brief duration of many studies. When asked about the
origins of his organization’s endorsement of flossing, he said
it may simply have “taken the ADA’s lead.” When the ADA was
asked for proof of its claim that flossing helps prevent early
gum disease and cavities, the group cited the 2011 review and a
2008 two-week study that measured bacteria and did not consider
gum disease. A spokesman for the dental association,
acknowledged weak evidence, but he blamed research participants
who did not floss correctly.
The global floss market
is almost $2 billion, with half in the United States. The floss
industry has paid for most studies and sometimes designed and
conducted the research. Procter & Gamble, which claims that
its floss fights plaque and gingivitis, pointed to a two-week
study, which was discounted as irrelevant in the 2011 research
review. Johnson & Johnson said floss helps remove plaque.
When the AP sent it a list of contradicting studies, J&J
declined comment.
Floss can occasionally
cause harm. Careless flossing can damage gums, teeth and dental
work. Though frequency is unclear, floss can dislodge bad
bacteria that invade the bloodstream and cause dangerous
infections, especially in people with weak immunity, according
to the medical literature.
Generally dentists
agree that there is a possibility that it works and are
comfortable telling people to floss. It is interesting to note
that, with two billion dollars at stake, no one is willing to
actually do a real study and perhaps find that the king really
has no clothes on. . .