Adults who clean between their teeth regularly have measurably less gum disease. A 2018 analysis of CDC NHANES data (which pairs interview answers with actual dental examinations) found the relationship graded with frequency: the most frequent interdental cleaners had the least severe disease.2 The data is observational, so this is an association, not proven causation.
What does the national data show?
One habit consistently separates adults with gum disease from adults without it in the national data: cleaning between the teeth. And this is not a rare condition you can wave off as someone else's problem: by the CDC's own measurement, about 42% of American adults over 30 have some form of gum disease,1 a scale we cover in how common gum disease really is. So among tens of millions of affected adults, what separates the people who have it from the people who don't?
One of the best answers comes from a 2018 analysis in the Journal of Dental Research. Researchers led by Julie Marchesan at the University of North Carolina examined data from NHANES (the CDC's large national health survey, which pairs interview questions with actual dental examinations) to see how interdental cleaning habits lined up with examiner-measured gum disease.2
The pattern was clear: adults who reported cleaning between their teeth regularly had measurably less gum disease than adults who didn't.
Why would that connection make sense? Gum disease is driven by plaque: a film of bacteria that builds up where a toothbrush has the hardest time reaching, in the tight contacts between teeth and just under the gumline. Interdental cleaning is the one daily habit aimed squarely at those spots. So when a national dataset shows the people who do it carrying less of the disease that starts there, the finding isn't just statistically tidy: it's biologically plausible.
Does more cleaning mean less disease?
In this data, yes. The relationship graded: the most frequent interdental cleaners had the least severe disease.2 It wasn't just that cleaners beat non-cleaners. Researchers call that a dose-response pattern, and it's what makes this analysis more persuasive than a simple two-group comparison.
The more regularly adults cleaned between their teeth, the less severe their gum disease: a graded, dose-response pattern in the national data.
Dose-response matters because it's harder to explain away. If interdental cleaning had nothing to do with gum health and the association were pure coincidence, you wouldn't expect the relationship to step down neatly with frequency. When more of the habit tracks with less of the disease, the association starts to look like more than noise, though, as we'll get to, it still can't prove cause.
It's also worth noting who ran the numbers. This analysis came from academic researchers with no industry funding behind the result: the same conflict-free lead author whose later five-year study found that flossers kept more of their teeth.
Does a second study point the same way?
Yes: the Marchesan analysis isn't alone. A 2017 study in the Journal of Clinical Periodontology, by Cepeda and colleagues, also examined national survey data and found that adults who flossed more than once a week had about 17% lower odds of periodontitis.3
One disclosure before you weight that number: the Cepeda study was funded by Johnson & Johnson, a company that sells floss. That doesn't make the finding wrong, but it's exactly the kind of thing an evidence-first library should tell you, and it's why we lead with the conflict-free Marchesan analysis and treat this one as corroboration rather than the anchor. Two independent teams, two datasets, one direction.
What can this data actually prove?
Everything above is observational: researchers observed habits and disease as they exist in the population; they didn't assign anyone to floss for a decade and watch what happened. So the honest framing is association, not proven causation. People who clean between their teeth may also differ in other health habits, and the cleaning frequencies are self-reported, which carries the usual grain of salt.
There's also a complementary kind of evidence worth knowing about: randomized clinical trials, which can speak to cause and effect but only over short timeframes. The best summary of those (Cochrane's systematic review) finds that cleaning between the teeth reduces gum inflammation, the earliest stage of gum disease. We walk through that review, including its honest limitations, in what the strongest clinical reviews actually show.
Put the two together and you get the fair, unexaggerated summary of the evidence: in trials, interdental cleaning reduces gum inflammation; in large national surveys, regular interdental cleaning is associated with less gum disease, and the most frequent cleaners have the least severe disease. Given that gum disease affects roughly two in five adults over 30, a cheap daily habit that consistently sits on the right side of that data is hard to ignore.
Common questions
Does cleaning between your teeth prevent gum disease?
The evidence doesn't support the word "prevent." In large national surveys, regular interdental cleaning is associated with less gum disease, and the most frequent cleaners have the least severe disease.2 In clinical trials, cleaning between the teeth reduces gum inflammation, the earliest stage. Association and reduced inflammation are what the data shows; prevention is not a claim it can carry.
What is a dose-response pattern, and why does it matter?
It means the relationship grades with the amount of the habit: the most frequent interdental cleaners had the least severe disease.2 That matters because coincidence becomes harder to invoke. If the association were pure noise, you wouldn't expect the disease to step down neatly as the habit increases.
How much lower are the odds of gum disease for people who floss?
A 2017 study of national survey data found adults who flossed more than once a week had about 17% lower odds of periodontitis.3 That study was funded by Johnson & Johnson, a company that sells floss, which is why this site treats it as corroboration and leads with the conflict-free 2018 Marchesan analysis instead.
Is self-reported cleaning frequency a problem for this data?
It's a real limitation. Participants described their own cleaning habits, which carries the usual grain of salt about over-reporting good behavior. The disease side of the data is stronger: NHANES pairs the interview questions with actual dental examinations, so gum disease was measured by an examiner rather than self-described.2
How does this fit with the clinical-trial evidence?
They cover different timeframes. Trials can speak to cause and effect but only over weeks to months, and they show interdental cleaning reduces gum inflammation. Surveys cover years of real-world habits but can only show association. Put together (as we do in what the strongest clinical reviews actually show): cleaning between the teeth reduces inflammation in trials, and regular cleaning is associated with less gum disease in the population.
- Eke PI, et al. / CDC. Periodontitis prevalence among US adults, NHANES 2009–2014; NIDCR data pages (2024). ~42% of adults 30 and older.
- Marchesan JT, et al. Interdental cleaning is associated with decreased oral disease prevalence. Journal of Dental Research, 2018. PMC6728587. NHANES survey data with dental examinations; self-reported cleaning frequency; observational association with dose-response.
- Cepeda MS, et al. Association of flossing/inter-dental cleaning and periodontitis in adults. Journal of Clinical Periodontology, 2017. ~17% lower odds of periodontitis for flossing more than once a week. Funded by Johnson & Johnson.