Yes, flossing is good for you. Adding floss to your brushing routine reduces gum inflammation and removes bacteria that your toothbrush physically cannot reach. The evidence isn’t as dramatic as you might expect from decades of dental advice, but it consistently points in one direction: cleaning between your teeth protects your gums, and healthy gums protect more than just your mouth.
What the Evidence Actually Shows
A large Cochrane review of clinical trials found that flossing in addition to brushing reduced gingivitis (early gum disease) compared to brushing alone, though the certainty of the evidence was rated low. Results for plaque reduction were less consistent. That’s the honest picture: flossing helps, but the proof isn’t as rock-solid as you’d think for something dentists have recommended for generations.
Here’s the important context. In 2016, an Associated Press investigation made headlines claiming flossing had never been proven effective. That story was based on the same reviews showing weak evidence. But the researchers behind those reviews explicitly stated their trials “were of poor quality and conclusions must be viewed as unreliable.” The accurate takeaway wasn’t “flossing doesn’t work.” It was “we don’t have enough high-quality trials to prove it works in the specific way clinical research demands.” Those are very different statements. Running a gold-standard trial on flossing is genuinely difficult. You can’t ethically tell a group of people to stop all interdental cleaning for years and then measure how much disease they develop.
Beyond the randomized trials, a large body of observational evidence supports the idea that regular, effective flossing promotes healthier gums. The studies that showed weak results also relied on participants self-reporting how often they flossed, with no verification of whether they were flossing correctly or consistently. Anyone who has watched someone floss for the first time knows technique matters enormously.
Why the Space Between Teeth Matters
Your toothbrush bristles can’t physically reach the surfaces where two teeth press together. Bacteria colonize these gaps and form a sticky film called plaque. Left undisturbed, that plaque matures. Early plaque is mostly harmless bacteria, but over time it shifts to a more aggressive mix of organisms associated with gum disease and tissue destruction. Eventually, plaque hardens into tarite (calculus), which only a dental professional can remove.
When those bacteria thrive unchecked between your teeth, the immune response they trigger causes your gums to become inflamed and bleed. That’s gingivitis. If it progresses, the infection can deepen into the bone and ligaments supporting your teeth, a condition called periodontitis that can lead to tooth loss.
The Connection to Heart Health
Periodontal disease doesn’t stay in your mouth. People with gum disease consistently show higher levels of C-reactive protein and other inflammatory markers in their bloodstream. A meta-analysis published in Frontiers in Cardiovascular Medicine found that periodontal disease is associated with increased cardiovascular risk independent of sex, with systemic inflammation as the likely core mechanism. Bacteria and inflammatory byproducts from diseased gums enter the bloodstream and can contribute to arterial stiffness and cardiovascular disease development.
The encouraging flip side: treating periodontal disease has been shown to reduce arterial stiffness and lower circulating inflammatory markers. Daily interdental cleaning can reduce bleeding, suppress harmful bacteria, and help restore a healthier bacterial balance in the mouth. Researchers have specifically noted that promoting interdental hygiene during adolescence could help prevent both periodontal disease and its downstream cardiovascular effects.
Floss Before You Brush, Not After
A clinical trial comparing the two sequences found that flossing first, then brushing, resulted in significantly higher fluoride concentrations in the plaque between teeth. The logic is straightforward: flossing loosens debris and breaks up bacterial film, then brushing sweeps it away and delivers fluoride into the freshly cleaned gaps. If you brush first and floss second, the fluoride from your toothpaste has less access to those interdental surfaces.
How to Floss Properly
Technique is the difference between flossing that works and flossing that’s just a habit. The most common mistake is snapping the floss straight down between teeth and pulling it back out. That skips the actual cleaning.
Start with about 18 inches of floss. Wrap the ends around your middle fingers, leaving about an inch of floss between your thumbs and forefingers. Slide the floss gently between two teeth, then curve it into a C-shape around one tooth. Rub it up and down along the side of that tooth several times, reaching just under the gumline until you feel gentle resistance. Then curve the floss around the neighboring tooth and repeat. Work through every tooth, including the back side of your last molars, using a fresh section of floss as you go.
The key word is gentle. Forcing or snapping the floss into your gums causes pain and bleeding that has nothing to do with gum disease, and it’s the main reason people quit flossing.
Interdental Brushes and Water Flossers
If you hate string floss, you have options that may actually work better for you. Interdental brushes, those tiny bottle-brush-shaped picks, have performed impressively in clinical comparisons. One study found they reduced plaque by roughly 40% and gum inflammation by about 43%, significantly outperforming traditional floss in the same trial. They’re also easier to use, which means people are more likely to stick with them.
Water flossers use a pressurized stream of water to flush bacteria and debris from between teeth and below the gumline. Systematic reviews have found them more effective than string floss at reducing gingival bleeding, though their effect on plaque scores is more modest. They’re especially useful if you have braces, dental implants, or bridges that make string floss difficult to navigate.
The best interdental cleaning tool is the one you’ll actually use every day. If string floss sits untouched in your drawer, switching to an interdental brush or water flosser is a legitimate upgrade, not a compromise.