P. gingivalis has been shown that it can migrate from the mouth to the brain. It is also found in the brains of Alzheimer's sufferers. But we don't know yet if it is THE cause of Alzheimer's. Which is to say "more research is needed to prove a cause and effect link."
This is still fresh science, the ink is still wet. It might ultimately prove that the cause of Alzheimer's is P. gingivalis (which is Nobel Prize levels of incredible). However, this single 2018 study is far from the body of evidence needed to make a claim on causal link.
That being said: Please brush and floss. There's no downside. Even if it is unlinked to Alzheimer's you've gained something and lost nothing. You'll thank yourself in the long run either way.
PS - I'm not even calling the science here bad (it is not). I am simply saying, this is the start of a marathon and the article is treating it like the end. Ten years ago similar articles on prion-based infections causing Alzheimer's was the hotness, until it wasn't.
I wouldn't go as far as to say there's NO downside. Of course this makes me sound like a kook, but in the interest of full transparency: If you are using fluoridated toothpaste there are side effects of the fluoride, not to mention the other synthetic chemicals in there like sulfates that mess with your gut - and Oral-B Glide floss is made with teflon-like substances (PFAS) that accumulate in your body and cause problems.
But then again brushing with fluoridated toothpaste is one of the few dental interventions with good evidence supporting it's effectiveness (unlike flossing for instance).
I find it hard to believe this sudden flurry of doubt about flossing, just based on my own experience. I have quite packed together teeth and find flossing very fiddly, so am very inconsistent with it.
When I don't floss, after 3 or 4 months, my gums start to puff up and bleed when brushed. When I do floss at least once a week, they don't.
It was especially obvious when I smoked, a few months after visiting the dentist/hygienist I would get bleeding from my gums, at times quite worrying amounts and one of the many reasons I gave up. However, after a few nights of flossing, it would always reduce significantly.
"There's no good evidence that flossing is effective for preventing dental carries and periodontal disease vs brushing alone" is not the same as "flossing is not effective for preventing dental carries and periodontal disease vs brushing alone." Just because evidence for something doesn't exist or is weak doesn't mean it doesn't work, it just means we haven't done the high quality randomized studies to prove it works. And I'm not sure we'll ever have that, since these sorts of studies are expensive and there's ethical issues with asking a control group to stop flossing for years.
When done properly flossing is a very low risk intervention, is cheap, has a plausible mechanism of action, has anecdotal evidence for effectiveness, and makes you feel nice and clean afterwards. So you probably should still floss, even if there is no high quality evidence of effectiveness.
Almost all cultures have some mechanism of cleaning larger food particles between teeth, particularly back teeth. But, more to the point -- absence of evidence is not evidence of absence:
Yes, but that is all anecdotes. Nobody with any intelligence seriously believes flossing is useless, but we don't have science to prove it, and until we have science there is room for doubt. If you don't know any science it is reasonable to argue that a heavy object falls faster than a light one, but once you do some science it isn't reasonable. (it is also reasonable to argue the other way, but most people would laugh at your argument until science proves them wrong at which point they should change their stance)
Yes it was an anecdote, but perhaps I wasn't clear, my point is that almost anyone whose gums bleed can easily test the benefits of flossing.
A much better analogy would be that people are starting to claim that farts might not smell as there's no scientific studies that conclusively say so.
As dentists point out rather regularly since that meta-study came out, they can clearly tell who flosses and who doesn't. Puffy, bleeding gums? You don't floss.
You didn't have to labour the point about science quite so rudely, I am fully aware of the philosophy of science, thanks.
Perhaps puffy, bleeding gums are perfectly healthy, but that seems unlikely as they hurt and are unsightly. On the upside, we know an easy fix for them, flossing. Do you honestly think that everyone here, or in any dentist's surgery, is going to laugh at me for claiming that?
My anecdote: I floss very very rarely and still my gum never bleeds. So it might be helpful for you, but not for me (at least not for the preventing bleeding).
I don't think I follow. I believe we have the science to prove that having food stuck between your teeth is worse than not having food stuck between your teeth.
We have science that aluminium in the brain correlated to alzheimers, and aluminium cookware causes high level of aluminium in the brain - but further science can't find a connection with alzheimers and cookware. (Note, the above is the state of science as of 20 years ago, things may have changed)
>Nobody with any intelligence seriously believes flossing is useless
Incorrect, I've seen articles lately saying that flossing is useless because "there's no evidence that it's helpful". Seriously. I've even read that some dentists don't recommend it now.
It's pretty mind-boggling to me, but I have no reason to doubt mainstream journalism that makes these claims. Personally, I use an electric toothbrush, but that simply cannot get all the bits of food out from between my teeth, the way flossing does. How anyone can think leaving bits of food between your teeth all night is a good idea, I have no idea.
> When I don't floss, after 3 or 4 months, my gums start to puff up and bleed when brushed. When I do floss at least once a week, they don't.
That's effectively the very beginning of "gum disease"; your brushing of your teeth probably keeps it in check otherwise, but if you didn't brush or floss - imagine where that could lead to.
Smoking only makes the problems worse (IIRC, it makes the gums more sensitive to abrasion and tooth decay products).
It's ultimately best to brush and floss regularly, particularly before going to bed, or directly after eating. I'd say if you had to do one or the other, before bed and in the morning regularly would be best.
Something to keep in mind also is how you floss - you want the floss to go between your teeth, but don't let it "saw" into (and injure) your gums - think of it more like a toothpick.
On top of all this, go see your dentist regularly if you can afford it. Every 6 months is fine. You can get x-rays and other diagnostics (there's one for oral cancer, among other things - talk to your dentist) that can help with your overall health. I honestly believe (anecdote) that going to your dentist regularly can be more beneficial for your overall health than going to the doctor.
Though, on that last bit, I honestly don't understand why here in America they leave it up to the patient to schedule regular doctor visits. I even asked my doctor's office staff if they could re-schedule me 6 months or a year later, and they wouldn't do it ahead of time, just "call us in a year" - which of course I never did. I suck at such follow-ups, but I've gone regularly to the dentist every 6 months for the past 25+ years - because they always schedule the next 6-month follow-up for me before I leave the office.
I don't understand why it's not done as a matter of course by regular family practice doctors (though they seem to do this - I think - for children; but at some point you "age out" - or more often, leave home out from under your parent's care).
For sure, as always that which seems obvious may not be the case. On the face of it though, awaiting a definitive result as to the benefits or not of flossing and neglecting to remove that gooey matrix of dextrans on and around your teeth which certainly provides a happy hunting ground for a diverse collection of bugs, is possibly not the best strategy.
> Ten years ago similar articles on prion-based infections causing Alzheimer's was the hotness, until it wasn't.
I think it was not so long ago that I saw an article linking herpes viruses to Alzheimer's (which sounded much more plausible than an oral bacterium). Something must be causing those amyloid deposits...
A recent study I've seen suggests that all three might have a causal role to play. Going from memory, the research suggests that amyloid plaque is part of an immune response to pathogenic infections in the brain. So herpes or P. gingivalis infections might trigger the build up of the plaque. The other causal factor is that certain forms of these plaques have prion-like properties, in that they induce a malfolding that has increased toxicity.
Wouldn't it be incredible if multiple independent lines of inquiry converged into a single unified explanatory framework?
I don't know where I picked up the idea, but I've long thought that it makes a kind of sense that oral plaque and gum disease would be linked to heart and brain diseases.
It is possible that you might have been pre-conditioned to think that way by the colossal dental industry; which has put out a fair amount of graphic imagery ranging from the saccharine to alarming, surrounding various aspects of oral hygiene and endorsing a variety of bacteria destroying toothpastes & mouth-washes to plaque-hunting rotating brushes in multitude of configurations etc., which compounded by this topic appearing with some regularity on HN might be reinforcing some of your preconceived notions.
Regardless, maintaining basic oral hygiene should be de rigueur, despite how feasible or tenuous the link(s) to other conditions might be.
You would spend much more than 10 hours on dentists appointments if you don't do this. Brushing and flossing properly cannot be stated as a loss of anything - time, money, health, whatever, no matter how you try to frame it. Don't delude yourself and others.
Additionally, you may not notice it but it you don’t floss you are likely to have bad breath due to the food trapped between your teeth (it depends on the gaps between your teeth but any food that sits in your mouth will eventually smell like shit). Outside of the other benefits of flossing, knowing that my breath smells better and not worrying about it is worth the 5-10 minute effort once a day.
This is tangential to your post but flossing is one in a series of things (including: washing and refrigerating eggs, vaccinating for chicken pox, circumcision) that Americans insist are absolutely critical for health but that are virtually nonexistent in Europe (or at least here in the Netherlands)
This is still fresh science, the ink is still wet. It might ultimately prove that the cause of Alzheimer's is P. gingivalis (which is Nobel Prize levels of incredible). However, this single 2018 study is far from the body of evidence needed to make a claim on causal link.
That being said: Please brush and floss. There's no downside. Even if it is unlinked to Alzheimer's you've gained something and lost nothing. You'll thank yourself in the long run either way.
PS - I'm not even calling the science here bad (it is not). I am simply saying, this is the start of a marathon and the article is treating it like the end. Ten years ago similar articles on prion-based infections causing Alzheimer's was the hotness, until it wasn't.