> Twelve trials were included in this review which reported data on two outcomes (dental plaque and gum disease). Trials were of poor quality and conclusions must be viewed as unreliable. The review showed that people who brush and floss regularly have less gum bleeding compared to toothbrushing alone. There was weak, very unreliable evidence of a possible small reduction in plaque. There was no information on other measurements such as tooth decay because the trials were not long enough and detecting early stage decay between teeth is difficult.
Purely anecdotal, but I'm pretty sure I scrape some stuff off my teeth via flossing. In particular, there are areas near the rounded corners of my molars that, even after a good brushing, sometimes have stuff I can feel with my tongue. By looping the floss around as much of the tooth as possible and doing a few (not just one) up and down movements, it seems to get that stuff.
But the question is, is that stuff bad for your gum or teeth health? That's not something you should assume a-priori.
An analogy: Whenever you bath with soap, you remove a layer of oil off your skin - a layer that your body puts there to keep you moisturized and hydrated. If you bath and soap too often, your skin will suffer, not improve, even though you're "cleaning" your skin.
(http://summaries.cochrane.org/CD008829/flossing-to-reduce-gu...)
> Twelve trials were included in this review which reported data on two outcomes (dental plaque and gum disease). Trials were of poor quality and conclusions must be viewed as unreliable. The review showed that people who brush and floss regularly have less gum bleeding compared to toothbrushing alone. There was weak, very unreliable evidence of a possible small reduction in plaque. There was no information on other measurements such as tooth decay because the trials were not long enough and detecting early stage decay between teeth is difficult.
(http://ohg.cochrane.org/cochrane-oral-health-group-scope)