Editing Periodontal disease (section)

=== 1999 classification ===
The 1999 classification system for periodontal diseases and conditions listed seven major categories of periodontal diseases,<ref name="armitage1999">{{cite journal | vauthors = Armitage GC | title = Development of a classification system for periodontal diseases and conditions | journal = Annals of Periodontology | volume = 4 | issue = 1 | pages = 1–6 | date = December 1999 | pmid = 10863370 | doi = 10.1902/annals.1999.4.1.1 | s2cid = 24243752 | doi-access = free }}</ref> of which 2–6 are termed ''destructive'' periodontal disease, because the damage is essentially irreversible. The seven categories are as follows:

* [[Gingivitis]]
* [[Chronic periodontitis]]
* [[Aggressive periodontitis]]
* [[Periodontitis as a manifestation of systemic disease]]
* [[Necrotizing periodontal diseases|Necrotizing ulcerative gingivitis/periodontitis]]
* [[Abscesses of the periodontium]]
* [[Combined periodontic-endodontic lesions]]

Moreover, terminology expressing both the extent and severity of periodontal diseases are appended to the terms above to denote the specific diagnosis of a particular person or group of people.

====Severity====

The "severity" of disease refers to the amount of [[periodontal ligament]] fibers that have been lost, termed "clinical attachment loss". According to the 1999 classification, the severity of chronic periodontitis is graded as follows:<ref>{{cite web|url=http://www.cda-adc.ca/jcda/vol-66/issue-11/594.html|title=The Periodontal Disease Classification System of the American Academy of Periodontology — An Update|website=American Academy of Periodontology}}</ref>
* Slight: {{convert|1|–|2|mm|abbr=on}} of attachment loss
* Moderate: {{convert|3|–|4|mm|abbr=on}} of attachment loss
* Severe: ≥ {{convert|5|mm|abbr=on}} of attachment loss

====Extent====
{{unreferenced section|date=November 2018}}
The "extent" of disease refers to the proportion of the dentition affected by the disease in terms of percentage of sites. Sites are defined as the positions at which probing measurements are taken around each tooth and, generally, six probing sites around each tooth are recorded, as follows:

* [[Commonly used terms of relationship and comparison in dentistry|Mesiobuccal]]
* Mid-buccal
* Distobuccal
* Mesiolingual
* Mid-lingual
* Distolingual

If up to 30% of sites in the mouth are affected, the manifestation is classified as "localized"; for more than 30%, the term "generalized" is used.