Gum disease is a progression, not a single condition. It begins as gingivitis (inflammation where the gums meet the teeth, caused by the bacteria in plaque), which dentists generally consider reversible. Left untreated, it can advance to periodontitis, where the bone and connective tissue anchoring the teeth break down. That later damage does not grow back.
How does gum disease start?
Gum disease starts with plaque: every mouth grows it, a soft, sticky film of bacteria that builds up on the teeth continuously, all day, every day. That part is universal and unavoidable. What matters is what happens next.
When plaque is cleaned away regularly, it doesn't get the chance to cause trouble. When it isn't (especially along and just under the gumline, and in the tight spaces between teeth where a toothbrush struggles to reach), the bacteria in plaque irritate the gum tissue. Over time, plaque that stays put can harden into tartar (dentists call it calculus), which brushing and flossing can no longer remove; at that point only a professional cleaning can clear it. According to patient guidance from the National Institute of Dental and Craniofacial Research (NIDCR, part of NIH), this bacterial buildup is where gum disease begins.
Stage one: what is gingivitis?
Gingivitis is the earliest stage of gum disease. It is the body responding to that bacterial irritation the way it responds to irritation anywhere: with inflammation, here in the gums.
Gums with gingivitis may look red or slightly swollen instead of firm and pink, and they may bleed easily during brushing or flossing. What they usually don't do is hurt, which is a big part of why gingivitis so often goes unnoticed and unaddressed.
Gingivitis is the stage dentists generally consider reversible. The inflammation is real, but the structures that anchor the teeth are still intact.
That's the crucial fact about stage one: at the gingivitis stage, the damage hasn't yet reached the bone and connective tissue that hold the teeth in place. With consistent daily care and professional cleaning, dentists generally consider gingivitis reversible. The strongest clinical reviews (from Cochrane, the gold standard for weighing medical evidence) find that cleaning between the teeth, on top of brushing, reduces gum inflammation; the certainty is modest, but the direction is consistent.3 We look at exactly what "reversible" means, and what the evidence says, in can gingivitis be reversed?
Stage two: what is periodontitis?
Periodontitis is the stage where inflammation has advanced past the gums into the deeper structures around the tooth (what happens when gingivitis is left to run), and it's a different kind of problem.
In periodontitis, per NIDCR patient guidance, the gums begin to pull away from the teeth, forming pockets where more bacteria collect below the gumline, out of reach of any brush or floss. The body's ongoing inflammatory response, combined with the bacterial infection, starts to break down the connective tissue and bone that support the teeth. Gums may recede, making teeth look longer. Teeth can gradually loosen. In advanced disease, they can be lost: periodontitis is a leading cause of tooth loss in adults.
And here's the asymmetry that makes the stages worth understanding: while gingivitis is generally considered reversible, the bone and tissue lost to periodontitis do not simply grow back. Treatment at that stage (professional deep cleaning, and in advanced cases surgery) is about stopping further destruction and managing the disease, not undoing it. That's why the whole game is catching gum disease at stage one, while it's still an inflammation problem rather than a structural one.
Why do the spaces between teeth matter so much?
They matter because that is where this whole story keeps happening: at the gumline and between the teeth, precisely the places a toothbrush covers least well. That's why dental guidance has always paired brushing with cleaning between the teeth, and it's why the Cochrane finding above matters: cleaning between the teeth reduces gum inflammation, which is the earliest stage of the disease process described on this page.
To be precise about what the evidence does and doesn't say: no tool has been proven to prevent or cure periodontitis, and you should be suspicious of anyone who claims otherwise. What the research supports is more modest and still meaningful: people who clean between their teeth regularly are associated with less gum disease, and trials show interdental cleaning reduces the gum inflammation where the disease begins. We walk through that evidence in flossing and gum disease: what the data shows.
The plain-language summary
Plaque builds up. Uncleaned plaque inflames the gums. That's gingivitis, the reversible stage. Untreated, the inflammation can advance to periodontitis, where the bone and tissue anchoring the teeth break down, and that damage doesn't reverse. The disease is common, it starts quietly, and the earliest stage is the one you can do the most about. The rest of this library takes each of those facts in turn, starting with just how common gum disease really is.
Common questions
Is gum disease the same thing as gingivitis?
Not quite. Gingivitis is the earliest stage of gum disease: inflammation of the gums that dentists generally consider reversible. Periodontitis is the later stage, where the bone and connective tissue supporting the teeth break down. Both are gum disease; only one is still reversible.
Can periodontitis be reversed?
No. The bone and tissue lost to periodontitis do not simply grow back. Treatment at that stage (professional deep cleaning, and in advanced cases surgery) is about stopping further destruction and managing the disease, not undoing it. Gingivitis, the earlier stage, is the one generally considered reversible; we look at what that means in can gingivitis be reversed?
What is tartar, and can I remove it at home?
Tartar (dentists call it calculus) is plaque that has stayed in place long enough to harden. Once it forms, brushing and flossing can no longer remove it. At that point only a professional cleaning can clear it.
Does cleaning between the teeth prevent gum disease?
No home tool has been proven to prevent or cure periodontitis. What the research supports is more modest: people who clean between their teeth regularly are associated with less gum disease, and Cochrane's review of home interdental cleaning found that cleaning between the teeth, in addition to brushing, reduces gum inflammation, with the certainty of the evidence rated as modest.3
- NIDCR/NIH, "Periodontal (Gum) Disease" patient guidance (2024); ADA patient guidance. Qualitative clinical descriptions of plaque, gingivitis, and periodontitis.
- StatPearls/NIH, "Periodontal Disease" (2023). Clinical reference on disease stages and progression.
- Worthington HV, et al. Home use of interdental cleaning devices, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries. Cochrane Database of Systematic Reviews, CD012018 (2019). Finding: cleaning between the teeth reduces gum inflammation; certainty modest.