American Academy of Periodontology Disease Classification

The fourth learning objective is to understand periodontal disease classification. The AAP updated its classification system for periodontal diseases in 2018 to create a common terminology compatible with scientific knowledge of periodontal diseases²⁵ Major changes included a new section classifying gingival diseases, replacement of the term “chronic periodontitis” with the term “periodontitis” and replacement of severity designations in specific locations with full mouth staging and grading levels.²⁵

Other less commonly occurring categories of periodontitis include disease associated with genetic disorders, necrotizing ulcerative periodontal diseases, abscesses of the periodontium, periodontitis associated with endodontic lesions and developmental or acquired deformities and conditions.

Periodontitis is commonly experienced by adults and it is known to occur in adolescents as well. Epidemiologic studies currently do not provide enough information to report exact prevalence due to the lack of consistency in study design, outcome measures and endpoints. In the 1996 Annals of Periodontology, Volume 1, Number 1, November, 1996, a review of the published data found that more severe forms of periodontal disease occur in approximately 10% of the population in developed countries, but that moderate attachment loss is more widespread. Variables of age, plaque and bleeding on probing are all found to be related to disease incidence and severity.⁶ Periodontitis is usually, but not always, a slowly progressing form of periodontitis that often responds to treatment. The rate of progression is captured by grading the disease. For example, periodontitis staging considers severity via interdental clinical attachment loss (CAL) as slight at 1-2 mm, moderate at 3-4 mm, and severe at 5 or more mm of loss. Staging also considers disease complexity and extent or distribution. Periodontitis grading considers evidence of progression and risk factors that modify grading.²⁵

Studies show that patients may experience periods of relative quiescence and bursts of rapidly progressing disease activity.⁷ This course focuses on periodontitis; by far the most common form of the disease.