True, you say?
Not quite, according to a recent literature review in Evidence-Based Dentistry.
The authors looked at randomized, controlled trials that compared the effects of brushing and flossing with brushing alone. All 12 of the studies that met their criteria showed some evidence that brushing and flossing together reduce gum disease more than brushing alone. Ten showed evidence of plaque reduction after one or three months. Yet the authors stress that this evidence is “weak” and “very unreliable.”
Using the GRADE criteria to judge the evidence, studies were determined to be of very low quality. This means we cannot be certain as to the estimate of the effect (from the meta-analysis) of flossing on gingivitis or plaque reduction. None of the studies reported a sample size calculation. None described adequate sequence generation or concealment of the sequence allocation. Thus, seven studies were rated as having an unclear risk of bias and five at high risk of bias. Furthermore, seven studies were sponsored by industry. Two of the five studies that did not disclose sources of funding were both conducted by authors whose affiliations reveal possible or real association with the industry who produced the investigated products. Also, there was concern related to inadequate compliance in many studies and the potential influence of confounders as other possible sources of bias.
So does this mean no flossing, no problem?
No. It just means that there’s no clear evidence of benefit it provides beyond just brushing. And truth be told, most dental practices and treatments rest on limited scientific evidence. As a 2006 article (PDF) in the Journal of the California Dental Association noted, “Perhaps as little as 8 percent of what dentists do is justified by peer-reviewed, published, and appropriately analyzed dental research” (emphasis added).
We do know that biofilm left to its own devices leads to decay, especially when one eats a lot of refined carbs. Cleaning your teeth breaks up these microbial colonies, interrupting their decay-causing activities. The question isn’t whether you should clean your teeth but which ways are most effective?
One element of hygiene that has been borne out by research is the use of proxy brushes  to clean the necks of the teeth. (You may also hear them called “interproximal” or “interdental” brushes.) As a 2009 EBD meta-analysis indicated,
The evidence showed that interdental brush use as an adjunct to toothbrushing removes more dental plaque than brushing alone, being even more effective than dental floss or woodsticks in removing dental plaque. The evidence available for the effect on gingival inflammation is less conclusive. The reduction of pocket depth after the use of the interdental brush is more pronounced than with floss.