Periodontitis is a serious gum infection that destroys the bone supporting your teeth. It starts when bacterial buildup along and below the gumline triggers a prolonged inflammatory response, and your own immune system gradually breaks down the surrounding tissue and bone. About 42% of U.S. adults over age 30 have some form of periodontitis, and that number climbs to nearly 60% among adults 65 and older, based on national survey data from the National Institute of Dental and Craniofacial Research.
Unlike gingivitis, which is reversible gum inflammation, periodontitis causes permanent damage. The bone loss it creates cannot regrow on its own, and without treatment, it’s the leading reason adults lose teeth.
How Periodontitis Develops
Your mouth naturally hosts hundreds of bacterial species. In a healthy state, these bacteria and your immune system coexist in balance. Problems start when plaque, a sticky film of bacteria, accumulates and hardens into tarite (calculus) that you can’t remove with regular brushing. Over time, the bacterial community shifts from mostly harmless species to more aggressive ones. This shift from a balanced state to a disease-causing one is the core event that drives periodontitis.
Several particularly harmful bacteria are involved, including species that produce enzymes capable of directly breaking down tissue and disabling your immune defenses. One well-studied pathogen produces enzymes that degrade immunoglobulins and complement proteins, essentially dismantling the molecules your body sends to fight infection. As these bacteria colonize the space between your gums and teeth, your immune system responds with chronic inflammation. That inflammation, while intended to fight the bacteria, ends up destroying the bone and connective tissue anchoring your teeth. The gums pull away from the teeth, forming deeper pockets that harbor even more bacteria, creating a self-reinforcing cycle of damage.
Signs You May Have It
Periodontitis often progresses painlessly, which is why many people don’t realize they have it until significant damage has occurred. The hallmark signs include red or swollen gums, bleeding when you brush or floss, persistent bad breath, and gums that feel tender to the touch.
As the disease advances, you’ll notice gums receding from the teeth, making teeth look longer than usual. Lower premolars are particularly prone to gum recession on the outer surface. Teeth may feel loose or shift position, and you might notice changes in how your bite fits together. Pus between the teeth and gums, a bad taste in the mouth, and increasing spaces between teeth are signs of more advanced disease. Progressing damage shows up as deeper pocketing around the teeth, increased gum recession, or both.
How Dentists Diagnose and Stage It
Diagnosis involves measuring the depth of the pockets between your gums and teeth using a thin probe. Healthy gums typically have pocket depths of 1 to 3 millimeters. Pockets of 4 to 5 millimeters suggest moderate periodontitis, while pockets of 6 millimeters or deeper indicate severe disease. X-rays reveal how much bone has been lost.
The American Academy of Periodontology classifies periodontitis into four stages based on severity and complexity:
- Stage I: Early periodontitis with 1 to 2 millimeters of attachment loss and bone loss limited to the upper third of the tooth root. No teeth have been lost to the disease, and pocket depths are 4 millimeters or less.
- Stage II: Moderate periodontitis with 3 to 4 millimeters of attachment loss. Bone loss remains in the upper third of the root, and pocket depths reach up to 5 millimeters. Still no tooth loss.
- Stage III: Severe periodontitis with 5 or more millimeters of attachment loss. Bone loss extends to the middle third of the root or beyond, pocket depths reach 6 millimeters or more, and up to 4 teeth may have been lost.
- Stage IV: Advanced periodontitis with the same level of attachment and bone loss as Stage III, but with 5 or more teeth lost. At this point, chewing function is often compromised, teeth may be visibly drifting or flaring, and extensive rehabilitation is needed.
Dentists also assign a grade (A, B, or C) reflecting how fast the disease is progressing. Grade A means no measurable bone loss over five years. Grade B involves less than 2 millimeters of bone loss over five years. Grade C, the most aggressive, means 2 or more millimeters of loss in that same timeframe. Smoking and diabetes can bump the grade higher regardless of other measurements.
Who Is Most at Risk
Smoking is the single most significant modifiable risk factor. Smokers are roughly four times more likely to develop periodontitis than nonsmokers, and one large analysis of national health data estimated that nearly 75% of periodontitis cases were attributable to smoking. Smoking also undermines treatment: in one study following periodontal surgery, 47% of deep pockets in nonsmokers healed to healthy depths, compared to just 16% of similar pockets in smokers. Even after quitting, the elevated risk of tooth loss persists for at least a year.
Genetics plays a substantial role. Twin studies suggest that roughly half the variation in periodontitis severity can be attributed to genetic differences. People who carry certain genetic variations affecting inflammatory signaling have nearly seven times the odds of developing severe disease compared to those without the variation. When that genetic predisposition combines with heavy smoking, the risk of tooth loss jumps by 7.7 times.
Other risk factors include diabetes (particularly when blood sugar is poorly controlled), obesity, psychological stress, poor nutrition, certain medications that reduce saliva flow, and socioeconomic factors that limit access to dental care. Age, gender, and race also influence risk, with older adults, men, and certain racial groups showing higher prevalence.
Non-Surgical Treatment
The first-line treatment for periodontitis is scaling and root planing, a deep cleaning that goes below the gumline. Your dentist or hygienist uses specialized instruments to remove plaque and hardite from the tooth surfaces and root surfaces, then smooths the roots so gums can reattach more easily. This is typically completed in one to four sessions, sometimes with local anesthesia for comfort.
Clinical trials consistently show that scaling and root planing reduces pocket depths, with results measurable as early as four weeks and sustained out to at least seven months. The improvement is most pronounced in pockets that were 4 millimeters or deeper at the start. Studies also confirm that professional cleaning combined with instruction on home care is significantly more effective at reducing pocket depth than improved home care alone, meaning you can’t brush your way out of established periodontitis without professional intervention.
When Surgery Is Needed
If deep pockets persist after non-surgical treatment, periodontal surgery becomes an option. The most common procedure is flap surgery (pocket reduction surgery), where the gum tissue is folded back to allow thorough cleaning of the root surfaces and reshaping of damaged bone. The gums are then repositioned to fit more snugly around the teeth, reducing pocket depth and making daily cleaning more effective.
For significant bone loss, regenerative procedures can help rebuild some of what was lost. Bone grafts, using material from your own body, a donor, or synthetic substitutes, are placed into the defect to serve as a scaffold for new bone growth. Synthetic bone graft materials have become increasingly common in periodontal surgery and can promote stability around teeth that would otherwise be at risk for loss. These procedures aim to reverse some of the damage rather than simply halting progression.
Connections to Overall Health
Periodontitis is now recognized as far more than a mouth problem. Research has linked it to over 70 different health conditions, including cardiovascular disease, diabetes, Alzheimer’s disease, rheumatoid arthritis, certain cancers, respiratory diseases, inflammatory bowel disease, and pregnancy complications.
The connections work through multiple pathways. Bacteria from infected gum pockets can enter your bloodstream through ulcerated tissue, reaching organs throughout the body. Inflammatory molecules produced in diseased gums spill into circulation, fueling widespread low-grade inflammation. Periodontitis can also alter how immune cells are produced in bone marrow, creating white blood cells with a heightened tendency toward inflammation. There’s even a dietary pathway: when periodontitis makes chewing painful or difficult, people shift toward softer, often less nutritious foods, leading to metabolic imbalances. The relationship with diabetes is bidirectional. Poorly controlled blood sugar worsens periodontitis, and active periodontitis makes blood sugar harder to control.
Long-Term Maintenance
Periodontitis is a chronic condition. Even after successful treatment, ongoing professional maintenance is essential to prevent relapse. The American Academy of Periodontology recommends that most patients with a history of periodontitis start with professional cleanings every three months, as this schedule reduces the likelihood of disease progression compared to less frequent visits. Over time, your dentist may adjust the interval based on how stable your condition remains, with recommendations in the literature ranging anywhere from every two months to every six months depending on individual response.
At home, thorough daily brushing and cleaning between teeth with floss or interdental brushes is non-negotiable. Periodontitis can’t be cured in the traditional sense, since lost bone doesn’t come back on its own, but it can be managed well enough that you keep your teeth for life. The key is catching it before the damage becomes too extensive and staying consistent with maintenance once treatment is complete.