What Is Gum Disease and How Does It Progress
Gum disease is an infection of the tissues that surround and support your teeth. It is caused by plaque, a sticky film of bacteria that forms on teeth every day. When plaque is not removed by brushing and flossing, it hardens into tartar (calculus) that can only be removed by a dental professional. The bacteria in plaque and tartar produce toxins that irritate the gums and trigger an inflammatory response.
If the infection is caught early (gingivitis), the damage is limited to the gums and can be fully reversed. If left untreated, the infection progresses to periodontitis, where it destroys the bone and connective tissue that hold your teeth in place. This damage is not reversible, though treatment can stop it from getting worse. Gum disease is the leading cause of tooth loss in adults.
How Gum Disease Is Measured: Pocket Depth
Dentists and periodontists measure the severity of gum disease using a small instrument called a periodontal probe. The probe is gently inserted between the tooth and gum to measure the depth of the space (pocket) around each tooth. This is called periodontal probing.
Healthy gums have pocket depths of 1 to 3 millimeters with no bleeding when probed. Pocket depths of 4mm or more indicate gum disease. The deeper the pocket, the more advanced the disease. Your dentist also takes X-rays to evaluate bone levels around the teeth. Together, pocket depth and bone loss determine the stage of your gum disease.
Stage 1: Gingivitis
Gingivitis is the mildest form of gum disease and the only stage that is fully reversible. It affects the gums only and has not yet reached the bone.
Symptoms of Gingivitis
The most common signs of gingivitis are gums that bleed when you brush or floss, redness or swelling along the gum line, and gums that appear puffy rather than firm and pink. You may also notice persistent bad breath. Gingivitis is usually painless, which is why many people do not realize they have it.
Treatment and Reversibility
Gingivitis can be reversed with professional dental cleaning to remove plaque and tartar, followed by consistent brushing (twice daily), flossing (once daily), and regular dental visits. Your dentist may also recommend an antimicrobial mouthwash. If you improve your oral hygiene habits and keep up with professional cleanings, your gums can return to full health.
Pocket depths at this stage are typically 3 to 4mm with no bone loss visible on X-rays.
Stage 2: Mild Periodontitis
When gingivitis goes untreated, the infection can spread below the gum line and begin to affect the bone and connective tissue that support the teeth. This marks the transition from gingivitis to periodontitis.
Symptoms of Mild Periodontitis
Symptoms include continued bleeding when brushing or flossing, gums that have started to pull away from the teeth (early recession), and pocket depths of 4 to 5mm. You may notice that your gums look slightly lower on certain teeth. There is early bone loss visible on X-rays, though you may not feel any pain at this stage.
Treatment at This Stage
Mild periodontitis is treated with scaling and root planing, commonly called a deep cleaning. During this procedure, your dentist or hygienist removes plaque and tartar from below the gum line (scaling) and smooths the root surfaces (root planing) to help the gums reattach to the teeth. The procedure is done under local anesthesia and is usually completed in two visits.
While the bone loss that has already occurred cannot be reversed, treatment at this stage can stop the disease from progressing. Good home care after treatment is essential.
Stage 3: Moderate Periodontitis
Moderate periodontitis represents a significant progression of the disease. More bone has been lost, and the supporting structures of the teeth are noticeably weakened.
Symptoms of Moderate Periodontitis
At this stage, pocket depths measure 5 to 6mm. X-rays show moderate bone loss (up to one-third of the bone around affected teeth may be gone). Gum recession becomes more visible. Some teeth may begin to feel slightly loose. You may also notice that your teeth are shifting or that spaces are developing between teeth that were previously tight together. Pus may be present between the teeth and gums, and bad breath tends to be more persistent.
Treatment at This Stage
Scaling and root planing is still the first-line treatment, but your dentist may also prescribe local antibiotics placed directly into the deepest pockets. If pockets do not respond to deep cleaning, your periodontist may recommend flap surgery (pocket reduction surgery). During this procedure, the gums are lifted back, tartar is removed from deep pockets, and the gum tissue is repositioned to reduce pocket depth.
Bone grafting may be an option in some areas to regenerate lost bone. Your periodontist will evaluate whether your specific pattern of bone loss is a candidate for regeneration. At this stage, referral to a periodontist is typically recommended.
Stage 4: Severe Periodontitis
Severe periodontitis means substantial bone loss has occurred, and the teeth are at serious risk of being lost.
Symptoms of Severe Periodontitis
Pocket depths of 7mm or more are typical. X-rays show significant bone loss, often more than half of the bone around affected teeth. Teeth may be visibly loose and may shift position. Chewing may become painful. Gum recession is pronounced, and the roots of the teeth may be exposed. Abscesses (pockets of pus) can form in the gum tissue. Some teeth may no longer be savable.
Treatment at This Stage
Treatment for severe periodontitis is managed by a periodontist and may include flap surgery, bone grafting, and guided tissue regeneration where the anatomy allows it. Teeth that are too loose or too damaged by bone loss may need to be extracted. Replacement options include dental implants (if enough bone remains or can be grafted), bridges, or dentures.
Patients with severe periodontitis require ongoing periodontal maintenance, typically every 3 to 4 months rather than the standard 6-month cleaning schedule. Without consistent maintenance, the disease will continue to progress in the remaining teeth.
Stage 5: Advanced (End-Stage) Periodontitis
Advanced periodontitis is the final and most destructive stage of gum disease. Most of the bone supporting the teeth has been lost.
Teeth are severely loose, and many may have already fallen out or need extraction. Chewing is significantly impaired. The gums may be deeply receded, infected, and tender. At this point, the focus of treatment shifts from saving individual teeth to managing the infection, extracting teeth that cannot be saved, and planning for full-mouth restoration.
Patients with advanced periodontitis benefit from a team approach involving a periodontist for disease management and surgery, a prosthodontist for designing replacement teeth (implants, dentures, or bridges), and potentially an [oral surgeon](/specialties/oral-surgery) for extractions and bone grafting.
How to Prevent Gum Disease
Gum disease is largely preventable with consistent oral hygiene and regular dental visits.
Brush your teeth at least twice a day with a soft-bristled toothbrush and fluoride toothpaste. Floss once daily to remove plaque from between the teeth where your toothbrush cannot reach. Consider using an antimicrobial or anti-gingivitis mouthwash as an addition to brushing and flossing, not a replacement for them.
Visit your dentist for professional cleanings and exams at least twice a year, or more often if you have risk factors for gum disease. Risk factors include smoking or tobacco use (the single largest controllable risk factor), diabetes, hormonal changes during pregnancy, certain medications that reduce saliva flow, and a family history of gum disease.
If you notice bleeding gums, persistent bad breath, or gum recession, schedule a dental appointment promptly. Catching gum disease early, while it is still gingivitis, is the key to reversing it before permanent damage occurs.
When to See a Periodontist
A periodontist is a dentist who completed 3 years of additional residency training focused on the prevention, diagnosis, and treatment of gum disease and the placement of dental implants. General dentists treat gingivitis and mild gum disease regularly, but a periodontist is the appropriate specialist for moderate to severe cases.
See a periodontist if your pocket depths are 5mm or deeper, if you have been told you have bone loss, if your gums have not improved after a deep cleaning, if your teeth are loose, or if you need gum surgery. A periodontist can also help if gum disease has been a recurring problem despite good home care.
Learn more about periodontal training on our [periodontics specialty page](/specialties/periodontics).
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