How do we know something is 'obviously' good for you without research? NOTHING Is so cut and dry that you can make that statement. For example: organic food. Obviously, must be amazing for you. Got two great buzzwords in it: organic and food. Therefore, amazing for you. Does the research bear this out?

Similarly, homeopathy, reiki, psychic surgery, acupuncture.

Vaccines: foreign substance entering our body. Therefore, terrible for you. Stands to reason right?

How could you make such a sweeping statement claiming the higher ground that we must exist in such an enlightened age that we don't have to continually fight the battle for evidence based activities in all activities?

Research is just another tool. It happens to be a really good one, and when research contradicts common sense and intuition, research usually wins. ("Usually" because it can be flawed, just like anything else.)

But in the absence of research, we can still do better than just saying "uh, I dunno" in many cases.

The alternative isn't reasoning based on buzzwords, it's based on thought and available evidence. No, that's far from perfect, but it's also not going to lead you into homeopathy, reiki, psychic surgery, or acupuncture. Flossing has a plausible mechanism of action, unlike any of your examples. If it turns out that this plausible mechanism of action doesn't actually have any long-term benefits, then that sucks, but it doesn't mean we should give up on thinking about anything that hasn't been researched.

I'm sure there are plenty of medical journals documenting the effects of getting abrasive substances in your eyes.

Also, I doubt any of those documented effects are from properly designed studies, nor do they examine a long-term daily treatment regimen. Are you just assuming that daily treatment would be bad based on what happens after one instance, plus common sense and intuition?

"As for me, all I know is that I know nothing."

--Socrates

So I could argue that even research results aren't sufficient proof for efficacy. For example, why should a "significant result" be a better argument than personal experience?

Meh, 2/10. Not that slippery.

Public policy needs research. Human history is absolutely stacked with "obvious" truths turning out to be harmful falsehoods.

So you have a good point, there are always new things to discover, but this is obvious in a way that's understood and doesn't in any way call into question the legitimacy of dentistry.

For all we know, sugary carbs that tend to get stuck between teeth do their damage in minutes or a few hours and flossing at night won't help. Or flossing too soon removes enzymes in your saliva that protect teeth from buildup or disease.

But cavities are not the only problem you can have in your mouth.

Food particles left in the mouth for long periods can cause an inflammatory response in the gums. This can lead to bone loss in the jaw. And that can cause your cavity-free teeth to fall out.

Flossing through the space between tooth and gum can potentially remove such particles, which would help prevent gum disease. But it might not be necessary to do it every day. Once a week, maybe? After eating jerky or popcorn?

I have no idea how often it is necessary to floss to achieve a statistically significant reduction in any of the oral diseases, or how much of a difference there may be between flossing twice a day and flossing once a month.

My dentist recommends flossing whenever I brush. While the recommendation to floss is probably well supported, I suspect that the frequency may be more based on psychology than anything else. They just attach it to the brushing habit. Perhaps it would be better to attach it to "whenever you trim your fingernails", or "whenever you shave your legs", even though those are not related to oral hygiene.

Perhaps you can get a layer of magic plaque that protects the teeth. Who knows. Mine just get worse. They used to feel dirty without a brush. Now they feel horrible without a brush and floss. Sometimes I just wish for all my teeth to be ripped out.

Brushing and flossing are basic tenents of dentistry, and they haven't done the science?

The word is "tenets".

That said, they should get more studies done.

You could also be a bad flosser, so even the study could be flawed.

I think it is quite obvious that people who floss also brush their teeth more regularly, and that is enough to give them healthier smiles.

(Regarding the benefits of flossing, I'm agnostic.)

They definitely and easily see a difference seen between those who floss and brush and those who just brush.

Also, those who use Sonicare, especially when used properly around the gumlines, also tend to have healthier mouths than those who brush with an old brush.

The one thing that can throw a wrench in this whole thing is smoking. Smokers' mouths are disgusting basically no matter what.

Point being, I love research, but I trust those who put their hands in tens of thousands of mouths more than skeptics on ArsTechnica article comments.

Uh... yes, it does. See https://en.wikipedia.org/wiki/Contraposition

You mean healthier teeth?

On the note of tongues, using a tongue scraper is a great way to get rid of nasty bacteria that causes bad breath and spreads to the rest of the teeth/gums. Cheap and effective.

Gist is that tongue cleaning yields less bacteria (that's one major cause of bad breath), but they still recommend both brushing and tongue cleaning since the reduction of tongue bacteria didn't reduce plaque. I never claimed that it did though.

Tongue scrapers are cheap and awesome. It's amazing what kind of disgusting stuff you'll scrape off that thing. I'll nearly guarantee you better breath unless you have some serious other problems, like periodontitis.

A second source on elderly: https://www.ncbi.nlm.nih.gov/pubmed/16677187

"These results suggest that tongue care is essential for preventing oral disease and needs to be part of any oral care programme in elderly people."