Periodontics · for dental professionals and students
Search for periodontitis and you will find "7 types", "4 stages", "chronic" and "aggressive", sometimes all on the same page. That is because two classifications are in use: the 1999 system most textbooks were written with, and the 2017 system clinicians use today. This guide explains both, and answers two questions patients often ask: can periodontitis be cured, and what is the worst form of gum disease?
The 7 types are the 1999 categories: chronic, aggressive, systemic-disease related, necrotizing, periodontal abscess, perio-endo lesions and developmental or acquired conditions. Since 2017, chronic and aggressive periodontitis are one disease, described by stage I–IV (how severe) and grade A–C (how fast). Periodontitis cannot be reversed, but it can be stopped and kept stable.
What are the 7 types of periodontitis?
The list comes from the 1999 International Workshop classification of the American Academy of Periodontology. Next to gingival diseases, it named seven categories of destructive periodontal disease:
| 1999 category | In short |
|---|---|
| 1. Chronic periodontitis | The common, slowly progressing form, mostly in adults |
| 2. Aggressive periodontitis | Rapid attachment and bone loss, often in younger, otherwise healthy patients |
| 3. Periodontitis as a manifestation of systemic disease | Periodontitis linked to conditions such as some blood and genetic disorders |
| 4. Necrotizing periodontal diseases | Painful, rapidly destructive necrosis of the gingiva and attachment |
| 5. Abscesses of the periodontium | Localised collections of pus in the gingiva or periodontal tissues |
| 6. Periodontitis associated with endodontic lesions | Combined periodontal–endodontic (perio-endo) lesions |
| 7. Developmental or acquired deformities and conditions | Tooth- and tissue-related factors such as recession or mucogingival defects |
The 2017 World Workshop (AAP and European Federation of Periodontology) replaced this system. It recognises three forms of periodontitis: necrotizing periodontal diseases, periodontitis as a manifestation of systemic disease, and periodontitis. The old "chronic" and "aggressive" labels are merged into the last one. Abscesses, perio-endo lesions and mucogingival conditions are still recognised, but as separate conditions rather than types of periodontitis.
The 4 stages of periodontitis
The stage describes how much damage has been done and how complex treatment will be. It is set by the worst site in the mouth, based mainly on interdental clinical attachment loss measured with a periodontal probe, backed up by X-rays.
| Stage | Interdental attachment loss | Bone loss on X-ray | Tooth loss from periodontitis | Complexity |
|---|---|---|---|---|
| Stage I · initial | 1–2 mm | Coronal third, <15% | None | Probing depth ≤4 mm, mostly horizontal bone loss |
| Stage II · moderate | 3–4 mm | Coronal third, 15–33% | None | Probing depth ≤5 mm, mostly horizontal bone loss |
| Stage III · severe | ≥5 mm | Middle third of the root or beyond | ≤4 teeth | Probing depth ≥6 mm, vertical bone loss ≥3 mm, furcation class II–III |
| Stage IV · advanced | ≥5 mm | Middle third of the root or beyond | ≥5 teeth | As stage III, plus need for complex rehabilitation (bite collapse, drifting, fewer than 20 teeth) |
Swipe to see the full table →
The stage is also described by extent: localised (under 30% of teeth), generalised (30% or more) or molar–incisor pattern.
The 3 grades of periodontitis
The grade describes how fast the disease progresses and how likely it is to respond to treatment. Clinicians start from grade B and move to A or C depending on the evidence and the patient's risk factors.
| Grade | Progression | Bone loss ÷ age | Risk factors that raise the grade |
|---|---|---|---|
| Grade A | Slow: no loss over 5 years | <0.25 | Non-smoker, no diabetes |
| Grade B | Moderate: <2 mm over 5 years | 0.25–1.0 | Smoking <10 cigarettes/day, or diabetes with HbA1c <7.0% |
| Grade C | Rapid: ≥2 mm over 5 years | >1.0 | Smoking ≥10 cigarettes/day, or diabetes with HbA1c ≥7.0% |
Example diagnosis: "Generalised periodontitis, stage III, grade B." In the 1999 system, most of these patients would have been called "chronic periodontitis"; a young patient with rapid bone loss would have been called "aggressive" and is now typically grade C.
Can you ever get rid of periodontitis?
Gingivitis, inflammation without attachment loss, is fully reversible: remove the biofilm and the gums heal. Periodontitis is different. Lost attachment and bone do not grow back on their own, and a patient who has had periodontitis stays susceptible for life.
What treatment can do is stop the disease. The goal is stable periodontitis: shallow pockets of 4 mm or less, no bleeding at 4 mm sites and very little bleeding elsewhere. In selected bone defects, regenerative surgery can rebuild part of what was lost. The European Federation of Periodontology's treatment guideline sets out four steps:
| Step | What happens | Typical instruments |
|---|---|---|
| 1. Risk factors and home care | Oral hygiene instruction, supragingival biofilm control, smoking cessation and diabetes control | Mirror, probe, explorer, sickle scaler |
| 2. Subgingival instrumentation | Scaling and root planing of the pockets, by hand or ultrasonic | Universal and Gracey curettes, ultrasonic scaler |
| 3. Treating residual pockets | Re-instrumentation or periodontal surgery (access flap, resective or regenerative) | Periodontal knives, periosteal elevators, micro instruments |
| 4. Supportive periodontal care | Recall every 3–12 months to keep the disease stable | Probe, curettes, implant-safe curettes |
Supportive care is lifelong. Recall intervals of 3 to 12 months are set by the patient's risk: smoking, diabetes, home care and how much disease remains.
What's the worst gum disease you can have?
It depends on what "worst" means.
- Most advanced common form: stage IV, grade C periodontitis. Severe attachment and bone loss, five or more teeth already lost, and rapid progression, often in smokers or people with poorly controlled diabetes. The whole dentition is at risk.
- Most aggressive form: necrotizing periodontal diseases. Painful, fast tissue death with "punched-out" papillae, bleeding and bad breath. They form a continuum from necrotizing gingivitis to necrotizing periodontitis and necrotizing stomatitis. Risk factors include smoking, stress, poor oral hygiene and a weakened immune system.
- The extreme end: noma. A rare orofacial gangrene that mainly affects severely malnourished children in low-resource settings. Untreated, it is fatal in most cases.
For patients: this article is written for dental professionals and students. If your gums bleed, recede or feel sore, see your dentist or hygienist for a proper examination.
From diagnosis to instruments
Staging starts with a probe; treatment runs on curettes. See which instruments periodontists use at each step, with pictures.
Questions
Frequently asked questions
What are the 7 types of periodontitis?
The '7 types' come from the 1999 AAP classification of destructive periodontal diseases: chronic periodontitis, aggressive periodontitis, periodontitis as a manifestation of systemic disease, necrotizing periodontal diseases, abscesses of the periodontium, periodontitis associated with endodontic lesions, and developmental or acquired deformities and conditions. Since the 2017 World Workshop, chronic and aggressive periodontitis are one disease, 'periodontitis', described by stage (I–IV) and grade (A–C).
Can you ever get rid of periodontitis?
Gingivitis is fully reversible. Periodontitis is not cured in the sense that lost bone and attachment grow back on their own, but it can be stopped and kept stable for life with professional treatment, good daily cleaning, control of risk factors such as smoking and diabetes, and regular supportive care. Some bone defects can be partly rebuilt with regenerative surgery.
What's the worst gum disease you can have?
Among common periodontitis cases, Stage IV Grade C is the most severe: advanced attachment and bone loss that progresses quickly and threatens the whole dentition. The most aggressive gum diseases are the necrotizing periodontal diseases, which can progress from necrotizing gingivitis to periodontitis and stomatitis; the extreme end is noma, a rare but life-threatening gangrene seen mainly in severely malnourished children.
What is the difference between gingivitis and periodontitis?
Gingivitis is inflammation of the gums only, with bleeding but no loss of attachment, and it heals when the biofilm is removed. Periodontitis has destroyed part of the attachment and bone around the tooth; that damage is measured with a periodontal probe as clinical attachment loss and on X-rays.
Is chronic periodontitis still a diagnosis?
Not in the current classification. Since 2017, 'chronic' and 'aggressive' periodontitis are merged into 'periodontitis' with a stage and grade, for example 'generalised periodontitis, stage III, grade B'. You will still see the old terms in older textbooks and records.
Sources
- Caton JG et al. A new classification scheme for periodontal and peri-implant diseases and conditions. J Periodontol 2018.
- Papapanou PN et al. Periodontitis: consensus report of workgroup 2 of the 2017 World Workshop. J Periodontol 2018.
- Tonetti MS, Greenwell H, Kornman KS. Staging and grading of periodontitis. J Periodontol 2018; AAP staging and grading tables.
- Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999.
- Sanz M et al. Treatment of stage I–III periodontitis: the EFP S3 level clinical practice guideline. J Clin Periodontol 2020.
- Necrotizing periodontal diseases. StatPearls, NCBI Bookshelf; BDJ Team 2023.
