Except that studies have now shown that the effect is not obvious at all.

"Since doctors began saying that a string-based tooth scrapping was good for oral health, a handful of studies have been conducted. However, they all fall far short of what’s needed to make a convincing argument. A 2011 review of a dozen randomized controlled studies concluded that, “Overall there is weak, very unreliable evidence which suggests that flossing plus toothbrushing may be associated with a small reduction in plaque at 1 or 3 months.”

The US Agriculture and Health and Human Services departments quietly removed the flossing recommendation from the latest version of dietary guidelines.

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If anyone thinks that this is because the study's parameters are too narrow to show an effect, that is not the case. Other studies have successfully shown the benefits of flossing... if the dentist is the one performing it. But they haven't been able to show similar results when regular people do the flossing.

"Maybe the evidence that flossing reduces tooth decay or gum disease does not hold up because we are all such poor flossers. Superflossers, like the zealous hygienist at your dentist’s office, aim to “hug the neck of the tooth” and get below the gum line, Dr. Hujoel said.

But we common folk, staring woefully at our bathroom mirrors, tend to lightly give it the once-over.

A review of six trials found that when professionals flossed the teeth of children on school days for almost two years, they saw a 40 percent reduction in the risk of cavities.

So maybe perfect flossing is effective. But scientists would be hard put to find anyone to test that theory."

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Honestly, I'm not surprised at all. Years ago, my dentist strongly urged me to get my asymptomatic wisdom teeth removed. I then went home and did my own research on this subject. And what I found was the complete opposite of my dentist's recommendation.

But a new study of more than 6,000 patients in Greece found that only 2.7 percent of the teeth had a cyst or tumor. An older study, often cited by critics of routine extraction, found that only 12 percent of 1,756 middle-aged people who had not had impacted wisdom teeth removed experienced a complication.

Numerous comprehensive reviews of research, conducted by independent bodies not affiliated with oral surgeons, have concluded that there was no evidence to support routine prophylactic extraction of impacted but healthy wisdom teeth.

Britain’s National Health Service stopped paying for the procedure if there was no good reason for it after an analysis by its Center for Reviews and Dissemination at the University of York concluded in 1998 that there was no solid scientific evidence to support it. Also that year, the Royal College of Physicians of Edinburgh said that for patients who do not have a condition related to third molars or whose teeth would probably grow in successfully, removal is “not advisable.”

In 2005, a review by the respected Cochrane Collaboration said the number of extractions could be reduced by 60 percent if they were done only when patients were in pain or developed a condition related to wisdom teeth. The group also said there is “reliable evidence” that suggests that removing wisdom teeth does not prevent or reduce crowding of front teeth.

In 2008, the American Public Health Association dismissed arguments typically made for removing wisdom teeth: that adjacent teeth might be damaged, or that the teeth may harbor bacteria that cause periodontal disease. The association approved a policy saying these concerns do not justify the risks of surgery, which include possible nerve damage, complications from anesthesia. loss of the sense of taste and, very rarely, death.

“The few studies of long-term retention of impacted teeth have shown little risk of harm,” the association concluded.

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I've since brought this up with a few other friends who are dentists as well. They always start off by haranguing me for doing my own research, instead of following my dentist's recommendation. Then once I show them all the above evidence, which they have never seen before, they change their minds and accept that I'm probably right.

With a track record like that, I wouldn't be surprised at all if flossing turns out to be yet another sacred cow that's virtually pointless in reality.

I do have to say kudos to the dental field though. At least they are making efforts to validate their recommendations, using empirical studies. I wonder how many of the recommendations given by programmers/teachers/fitness-trainers etc are similarly flawed.

http://www.nytimes.com/2016/08/03/health/flossing-teeth-cavi...

http://www.nytimes.com/2011/09/06/health/06consumer.html