PERIODONTICS: Old Disease Gets A New Close. A Brief Review of the New Classification of Periodontal Diseases

by Peter Birek, DDS, MSc, Dip.Perio.

Given the shortcomings of the most current classifications for periodontal diseases (the 1989 World Workshop in Clinical Periodontology and the 1992, 1st European Workshop in Periodontology) and responding to the advancements in our understanding of the underlying disease mechanisms, the Academy of Periodontology initiated a review of the existing disease classification. The resultant International Workshop for a Classification of Periodontal Diseases and Conditions held in October 1999 resulted in a new classification. This is a brief review of it. Short suggestions, highlighted in the text, will aid the everyday practitioner to navigate this new uncharted territory.


The addition of a gingival disease category does recognize the major influence of systemic conditions on the clinical expression of gingivitis. The differentiation between plaque- and non-plaque induced gingival conditions brings the etiology to the forefront, separating truly infections from various lesions secondary to systemic conditions that alter the host. It is also of note that for the first time it becomes clear that dental plaque-induced gingivitis can either occur on a periodontium with no attachment loss or in situations where attachment loss did occur but is non-progressing.

On noting red, puffy gingivae that bleeds easily on probing, without deep pocketing, regardless of the presence or absence of attachment loss, a diagnosis of gingivitis can be made. The condition can be either plaque induced or non-plaque induced (see Table 1).


The aged dependency of periodontitis, reflected in the old classification, was somewhat confusing. Pre-pubertal, early-onset, juvenile, adult periodontitis encompassed clear overlaps. When, in essence, the same disease characterized by destruction periodontium can occur at different ages a correction in classification was due. The new designation of Chronic Periodontitis represents the common variety of slowly progressive disease that can occur in patients of varied ages. It can be either localized (less than 30% of sites involved) or generalized (more 30% of sites involved). Its severity can also vary from Slight (1-2 mm of attachments loss), Moderate (3-4 mm of attachments loss) or Severe (more than 5 mm of attachments loss). Vast amounts of epidemiological data have been tabulated over the years in support of this category. It is the “garden variety” of periodontitis, one that may have given periodontist the nickname of “gum gardeners”.

It is clear to every dentist who has been around for more than five income tax returns that in a subset of patients, periodontal destruction progresses faster, making it distinct from the “chronic,” slowly progressing type. Hence the designation of Aggressive Periodontitis. This can be further divided into generalized and localized forms with slight, moderate and severe designations (see Table 2).

Loss of attachment, deep pockets and varied signs of infection means Chronic Periodontitis, at any age – either generalized or localized, with Slight, Moderate or Severe forms.


Traditionally this designation was given to disease that did not respond to competent and timely treatment in a healthy and compliant patient. It is true that patients who fall into this group were heterogeneous in nature, and that this diagnostic entity included perhaps more that one type of disease. Denying its existence would, in my view, sweep a very important group of patients “under the rug”. For this is the type of patient that needs most of our attention and effort and creates sleepless nights for the otherwise well sleeping “gum gardener”. Although the decision was made to discard it as a single all encompassing diagnostic category, the suggestion was made that the refractory attribute could be applied to every disease category. The suggestion that more research was necessary to understand the reasons why some patients fail to respond to treatment, was a frank recognition of our lack of knowledge about this issue.

If cooperative patients belonging to any disease entity fail to respond to competent and timely treatment you can assign the “refractory” attribute to its diagnostic designation. For example: Refractory Chronic Periodontitis. This means simply that the treatment did now work.


Varied forms of Manifestations of Systemic Diseases of the periodontium are well documented. A detailed discussion of these entities is beyond the scope of this article. For a review of the classification the reader can refer to Gary C. Armitage, Annals of periodontology, Vol. 4, Num. 1, December 1999 ( The same applies to Periodontitis Associated With Endodontic Lesions Developmental or Acquired Deformities and Conditions.


Over the years I had difficulty in deciding whether a periodontal abscesse was a sign of Chronic Periodontitis or a complication of it. The designation according to the location of the lesion, gingival, periodontal or pericoronal, was of little help. Although the abscess is part of the clinical course of several forms of periodontites, a single designation is warranted because abscesses represent significant diagnostic and treatment challenges. The new classification still allows some confusion about the place in the diagnostic constellation of an abscess arising from periapical periodontitis for example. Although the new classification designates a separate category of periodontitis associated with Endodontic Lesions, some clarification would have been desired.

Gingival swelling of purulent and fluctuant in nature is a periodontal abscess. It’s location will determine whether it deserves periodontal, gingival or pericoronal designation.


The two conditions called Necrotizing Ulcerative Ginginvitis (NUG) and Necrotizing Ulcerative Periodontitis (NUP) appear to be distinctly recognizable clinical conditions. It appears though that they represent the same pathological process in different stages of progression. Since this issue is not well understood, for the time being, the committee created a category called Necrotizing Periodontal Diseases (NPD). To add more to the confusion both NUG and NUP are well known manifestations of systemic diseases, such as HIV infections. This could argue for their inclusion under “Periodontal Manifestations of Systemic Diseases” category. To me Necrotizing Periodontal Diseases are aggressive disease forms of an impaired host.

Clinical appearance of ulcerative gingivae that leads to loss of soft tissue and periodontal attachment will fall under the Necrotizing Ulcerative Periodontitis diagnostic designation. The stage of progression will differentiate between NUG and NUP.


Of practical interest to the periodontal practitioners is the creation of a category named “Mucogingival Deformities and Conditions on Edentulous Ridges”. Although lack of (adequate) keratinized gingival tissue or vertical ridge deficiencies are arguably outside of the realm of periodontal diseases, existence of these entities will help in more efficient processing of varied insurance forms and claims that litter our front desks or computer desktops.

However imperfect it is, the new classification is a synthesis of current knowledge and understanding of disease mechanisms. Whether we like it or not, it will govern our practice for some years to come. Undoubtedly new knowledge will evolve which will lead to changes, confirming the old adage, “nothing is more constant than change”.

Peter Birek is Oral Health’s editorial board member for Periodontics.

Oral Health welcomes this original article.

Table 1

Plaque relatedNone – Plaque related
Gigival diseaseSpecific Bacterial Origin
Associated with dental plaque onlySpecific Bacterial Origin
Modified by systemic factorsSpecific Viral Origin
Modified by medicationsFugal Origin
Modified by malnutritionGenetic Origin
Secondary to Systemic Conditions
Mucocutaneous Disorders
Alergic Reactions
Attributed to toothpaste, mouthrinses etc.
Traumatic lesions