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September 2017
Volume 38, Issue 8

Revisiting the Classification of Periodontal Disease

Terrence J. Griffin, DMD

A lot can change in dentistry over the course of nearly two decades. This November the American Academy of Periodontology (AAP), in conjunction with the European Federation of Periodontology, will host the 2017 World Workshop on Periodontal Disease Classification, the first such meeting since 1999. More than 100 researchers and practitioners from around the world will gather in Chicago to review the latest literature and develop a consensus on the guidelines of periodontal disease diagnosis. Workshop attendees will be charged not only with re-evaluating existing evidence, but with making room for what the specialty has learned since the most recent set of guidelines was established 18 years ago.

Classification systems are designed to guide clinicians in the proper and simple diagnosis of a condition. Practical considerations also contribute to the importance of classification systems. In addition to laying a pathway for prognosis and treatment planning, established parameters also reduce the likelihood of excessive examination, which may induce trauma on already irritated gum tissue. Moreover, these systems provide a foundation for studying the factors of the cause and progression of an ailment.

In periodontics, infection can be determined by such factors as probing depths, bleeding on probing, radiographic bone loss, and clinical attachment loss. Periodontal disease classifications, which are eventually used as a standard for clinicians and researchers around the world, primarily take these measures into account in addition to other patient-specific factors, such as the presence of systemic illness or developmental deformities.

The field of periodontics has made such considerable advancements in the past 18 years that even the most learned clinicians are prompted to revisit and expand what classifies as disease. Consider the growing prominence of implant dentistry; its rise and its implications (peri-implantitis chief among them) have forged new ground that requires the thoughtful analysis essential to quality patient care.

This is not the first time that development and discovery have prompted the AAP to define and redefine disease. Periodontal disease classifications went from two categories in 1977, to four in 1986, to five in 1989.1 One notable change in this evolution came in 1989 with the added category of periodontitis associated with systemic disease. In the 1980s, periodontists were often the first to identify major physical illnesses (such as HIV) based on oral symptoms. These anecdotal observations and growing scientific evidence brought about the first formal explorations of the link between periodontitis and systemic conditions. The prescient recognition of this association’s impact and its inclusion in the 1989 disease classification set the stage for what the dental and medical communities have come to understand decades later about the bidirectional relationship between oral health and overall wellness.

The 1999 International Workshop for a Classification of Perio­dontal Diseases and Conditions addressed what were discovered to be shortcomings in the 1989 document. Disease groupings that saw significant overlap in 1989 resulted in the 1999 expansion to the following eight categories2: gingival 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 and acquired deformities and conditions.

In addition to including a section on gingival diseases, one notable change in the 1999 classification was the replacement of the phrase adult periodontitis with chronic periodontitis.3 Workshop participants decided that the use of the word adult might confuse practitioners who encounter younger patients with the condition. By then, literature and experience determined that this type of periodontitis was not necessarily a respecter of age. The shift was greater than semantics: clinicians, now empowered to understand the breadth of periodontitis’ impact, were no longer beholden to such a specific diagnostic description when seeing young patients.

During the upcoming 2017 World Workshop, participants will draft a comprehensive update to the 1999 guidelines that is slated to include classifications for peri-implant diseases and conditions. Measurements of periodontal and gingival health are also planned for inclusion in this update. Proceedings from the workshop will be published in a 2018 edition of the Journal of Periodontology.

For patients, for proper diagnosis, and for laying the foundation for effective treatment, everything is worth a second (or third or fourth or infinite) look. Because what we know is always evolving, guidelines must evolve as well.

About the Author

Terrence J. Griffin, DMD
Immediate Past President
American Academy of Periodontology
Private Practice
Boston, Massachusetts


1. The American Academy of Periodontology. Proceedings of the World Workshop in Clinical Periodontics. Chicago, IL: American Academy of Periodontology; 1989:1-22.

2. 1999 International Workshop for a Classification of Periodontal Diseases and Conditions. Papers. Oak Brook, Illinois, October 30-November 2, 1999. Ann Periodontol. 1999;4(1):1-112.

3. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol. 1999;4(1):1-6.

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