It's real science. Bacteria in your mouth can enter the bloodstream through wounds and travel to your heart.

//EDIT: Apparently, although the association between gum disease and heart disease seems to be science, the causal link is not.

It's not about bacteria entering your bloodstream (if that happened you'd have bigger problems), its the inflammation caused by your body fighting the bacteria influencing other organs. Inflammation isn't an acute action, the signalling molecules involved travel around the entire body. This can cause inflammation in completely unrelated areas. The heart is highly susceptible to this since all your blood travels through it.

What about wounds caused by flossing irregularly?

Seriously, and flossing undoubtedly pushes some food particles beneath the gum line.

wut?

You sure it isn't that people who floss tend to also be people that take better care of their bodies overall, and hence the two, while correlated, aren't an example of cause and effect.

Ehm, I'll admit that at this time no causal link is established although there is a correlation [1]. I've come to realize that I don't have a good source for what I wrote earlier.

Sources like [2] do claim a causal link but I was unable to find the actualy study.

[1] http://jama.jamanetwork.com/article.aspx?articleid=193088#qu... [2] http://abcnews.go.com/Health/dental-screenings-linked-lower-...

To be clear, I don't want to discount the studies completely, because there does seem to be a little bit of smoke there.

That said any real conclusions are clearly premature for the data, as science reporting tends to be these days.

Isn't that what the Lymphatic System is for? Bacteria do not simply enter the bloodstream, that would be a serious infection.

I believe the logic goes something like this: Research shows that perio disease may be linked to heart disease [1]. Flossing has been proven to reduce your chance of heart disease so it also reduces your chance of heart disease.

I'm not going to try and dig up a bunch of studies to back this up. I drank the Kool-Aid years ago. It appears to have paid off for me in the dentists chair!

[1]: http://www.perio.org/consumer/heart_disease

Correlation. Causation. Not the same.

People who floss twice a day tend to have all sorts of good habits. In fact, they tend to be the sort of people who just plain "take care of themselves."

Agreed! For the causation you'll have to read the extensive literature on periodontal disease.

Which won't help much, given that the second line in your link is: While a cause-and-effect relationship has not yet been proven

Agreed, the cause and effect between heart disease and periodontal disease is not well proven. However, the beneficial effects of flossing in preventing periodontal disease is well understood and you're welcome to read the literature yourself if you don't believe me. I believe this is exactly what I said in my original comment.