Development of a Classiﬁcation System for Periodontal Diseases and Conditions
Gary C. Armitage*
* University of California, San Francisco, California.
Classiﬁcation systems are necessary in order to provide a framework in which to scientiﬁcally study the etiology, pathogenesis, and treatment of diseases in an orderly fashion. In addition, such systems give clinicians a wayto organize the health care needs of their patients. The last time scientists and clinicians in the ﬁeld of periodontology and related areas agreed upon a classiﬁcation system for periodontal diseases was in 1989 at the World Workshop in Clinical Periodontics.1 Subsequently, a simpler classiﬁcation was agreed upon at the 1st European Workshop in Periodontology.2 These classiﬁcation systems havebeen widely used by clinicians and research scientists throughout the world. Unfortunately, the 1989 classiﬁcation had many shortcomings including: 1) considerable overlap in disease categories, 2) absence of a gingival disease component, 3) inappropriate emphasis on age of onset of disease and rates of progression, and 4) inadequate or unclear classiﬁcation criteria. The 1993 Europeanclassiﬁcation lacked the detail necessary for adequate characterization of the broad spectrum of periodontal diseases encountered in clinical practice. The need for a revised classiﬁcation system for periodontal diseases was emphasized during the 1996 World Workshop in Periodontics.3 In 1997 the American Academy of Periodontology responded to this need and formed a committee to plan and organize aninternational workshop to revise the classiﬁcation system for periodontal diseases. The proceedings in this volume are the result of this reclassiﬁcation effort. The process involved development by the Organizing Committee of an outline for a new classiﬁcation and identiﬁcation of individuals to write state-of-the-science reviews for each of the items on the outline. The reviewers were encouraged to departfrom the preliminary outline if there were data to support any modiﬁcations. On October 30–November 2, 1999, the International Workshop for a Classiﬁcation of Periodontal Diseases and Conditions was held and a new classiﬁcation was agreed upon (Fig. 1). This paper summarizes how the new classiﬁcation for periodontal diseases and conditions presented in this volume differs from the classificationsystem developed at the 1989 World Workshop in Clinical Periodontics.1 In addition, an analysis of the rationale is provided for each of the modifications and changes. Ann Periodontol 1999;4:1-6. KEY WORDS Periodontal diseases/classiﬁcation; gingival diseases/ classiﬁcation.
CHANGES IN THE CLASSIFICATION SYSTEM FOR PERIODONTAL DISEASES Addition of a Section on “Gingival Diseases” As mentionedabove, the 1989 classiﬁcation did not include a section on gingival diseases. This has been remedied by the development of a detailed classiﬁcation of gingival diseases and lesions that are either dental plaque-induced (pages 18-19) or not primarily associated with dental plaque (pages 30-31). An important feature of the section on dental plaque-induced diseases is acknowledgment that the clinicalexpression of gingivitis can be substantially modiﬁed by: 1) systemic factors such as perturbations in the endocrine system, 2) medications, and 3) malnutrition. The section on non-plaque induced gingival lesions includes a wide range of disorders that affect the gingiva. Many of these disorders are frequently encountered in clinical practice. Replacement of “Adult Periodontitis” With “ChronicPeriodontitis” From the outset, the term “Adult Periodontitis” created a diagnostic dilemma for clinicians. Epidemiologic data and clinical experience suggest that the form of periodontitis commonly found in adults can also be seen in adolescents.4 If this is true, how can non-adults (e.g., adolescents) with this type of periodontitis be said to have “adult periodontitis?” Clearly, the age-dependent...