Periodontitis breaks down the bone and connective tissue that anchor teeth, which is why dental guidance describes it as a leading cause of tooth loss in adults.3 In a five-year, NIH-funded study of adults 65 and older, people who reported flossing lost about 1 tooth over the period while non-flossers lost about 4: an association, not proven causation.1
How does gum disease lead to tooth loss?
By attacking the anchoring system rather than the tooth. A healthy tooth is held in place by a structure most people never think about: the gum tissue sealing around it, the ligament fibers holding it, and the jawbone underneath it all. Cavities attack the tooth itself. Periodontitis (the advanced stage of gum disease) attacks what holds it.
According to patient guidance from NIDCR/NIH and the ADA, periodontitis is a chronic infection and inflammation of the tissues that support the teeth. As it advances, the gums pull away from the teeth and form pockets, the ligament fibers break down, and the bone itself is gradually destroyed. A tooth in that condition can be perfectly free of cavities and still loosen, shift, and eventually be lost, because there's less and less holding it in. This is why dental guidance consistently describes periodontitis as a leading cause of tooth loss in adults.3
Periodontitis doesn't destroy the tooth. It destroys what the tooth stands on.
And because the early stages are essentially painless (a story we tell in full in the silent disease), much of that damage can happen quietly, over years, before anything hurts.
What did the five-year flossing study find?
It found that older adults who reported flossing lost about 1 tooth over five years, while non-flossers lost about 4: the most direct piece of evidence here, from an NIH-funded study published in the Journal of Dental Research in 2020.1
Researchers followed a group of older adults (participants were 65 and older) over five years and compared tooth loss between people who reported flossing and people who didn't. Overall, flossers averaged roughly 3 fewer missing teeth than non-flossers.
Three honest caveats belong next to that finding, and we won't hide them:
First, it studied older adults. The participants were 65 and older, so the numbers shouldn't be casually generalized to a 30-year-old's mouth. Though the biology of gum disease doesn't change with age, the pace of tooth loss does.
Second, flossing was self-reported. As with nearly all habit research, the researchers relied on people's own accounts of their flossing, which are imperfect.
Third, this is an association, not proven causation. The study adjusted for factors like diabetes, smoking, education, brushing, and dental visits, but an observational study can't prove that flossing itself caused the difference. People who floss may differ in other ways too.
With all of that said plainly: a five-year gap of roughly three teeth, in a peer-reviewed, NIH-funded study with no industry conflicts, is one of the most concrete data points in this entire library. We go deeper on it in flossers keep more teeth.
What is a kept tooth worth?
Every tooth you keep is a restoration you never need, a practical framing dental guidance tends to understate. A lost tooth doesn't just leave a gap; it usually starts a chain of dental work to fill it, whether that's a bridge, an implant, or a denture.
The market prices make the stakes concrete. A single crown typically runs $1,000–1,800, and a dental implant typically runs $3,000–6,000. Those are market ranges, not quotes, and they vary by region and case.2 Multiply the study's roughly-three-teeth difference by numbers like those and the value of the anchoring system under your teeth stops being abstract. We break down what restorations cost (and why prevention is the cheapest dentistry there is) in what restorations cost.
The takeaway, stated carefully
Here is what the evidence supports, no more and no less. Periodontitis breaks down the bone and tissue that anchor teeth, and it is a leading cause of adult tooth loss; that's standard clinical guidance. In older adults, daily flossing is associated with substantially less tooth loss over time; that's the five-year study, with its caveats attached. And once periodontitis has advanced, the damage to bone doesn't reverse on its own, which is why the earlier stage, gingivitis, is where the real opportunity sits. That's the subject of the next article: can gingivitis be reversed?
Common questions
Does gum disease always lead to tooth loss?
No. Periodontitis is a leading cause of adult tooth loss, but gum disease is a progression, and the earlier stage, gingivitis, is generally considered reversible with consistent daily care and professional cleaning.3 Even at the periodontitis stage, treatment is aimed at stopping further destruction. See can gingivitis be reversed?
Can bone lost to gum disease grow back?
Not on its own. Once periodontitis has broken down the supporting bone and tissue, treatment is about halting further damage and managing the disease rather than undoing it. In some advanced cases a periodontist can rebuild portions surgically, but that's damage control, not reversal, as treatment options, explained walks through.
Does the five-year study prove flossing prevents tooth loss?
No. It's an observational study, so it shows an association rather than proven causation. It adjusted for factors including diabetes, smoking, education, brushing, and dental visits, but people who floss may differ in other ways. Flossing was also self-reported, and the participants were 65 and older.1
What does replacing a lost tooth cost?
As market ranges rather than quotes, a single crown typically runs $1,000–1,800 and a dental implant typically runs $3,000–6,000, varying by region and case.2 That's the practical argument for the anchoring system under your teeth: every tooth you keep is a restoration you never need.
- Marchesan JT, et al. Flossing is associated with improved oral health in older adults. Journal of Dental Research, 2020;99(9):1047–1053. NIH-funded, five-year follow-up, adults 65+. PMC7375740. Self-reported flossing; association, not proven causation.
- ADA Health Policy Institute (2024); GoodRx (2025). Restoration market-price ranges: crown $1,000–1,800; implant $3,000–6,000. Market ranges, not fee-survey figures.
- NIDCR/NIH and ADA patient guidance on periodontal (gum) disease: mechanism of attachment and bone loss; periodontitis as a leading cause of adult tooth loss.