The new classification of periodontitis is modelled after the oncology system of staging and grading enabling a more multi-dimensional approach that incorporates not only severity of disease but rate of progression, the multifactorial etiology of the disease, its level of complexity for disease management and identification of risk for future disease recurrence or progression. This approach individualizes the diagnosis and case definition thus aligning it with the principles of personalized or precision medicine.11

The key elements necessary for classifying periodontal disease are:

Severity: Degree of periodontal breakdown
Complexity of Management: Type of bone loss (horizontal/vertical), probing depths, presence of furcations, tooth mobility, number of missing teeth, occlusal/functional aspects.
Extent: Number and distribution of teeth with detectable breakdown.
Rate of Progression: Rapidity of breakdown (direct or indirect observation).
Risk Factors: Smoking, Diabetes, overall compliance, general health.

Staging and Grading encompasses all of these necessary key elements. Staging includes classification of severity and extent of current tissue loss, including tooth loss (due to periodontitis), while incorporating the level of complexity in the long-term management of both function and esthetics. Grading on the other hand, incorporates the following biological dimensions: periodontitis progression based on history; risk for further periodontitis progression; anticipated inferior treatment outcomes; and risk that the disease or treatment may negatively impact the patient’s general health.12 Tables 7 and 8 summarize the essential components for determining the stage and grade of the periodontitis case.

Table 7. Overview of Staging (Severity).
Stage Description
  • Very incipient
  • CAL & BL limited to most coronal part of root
  • No periodontal pockets
  • No tooth loss from periodontitis
Mild Periodontal disease - Stage 1
  • Periodontal destruction in coronal third of root
  • Presence of moderate pockets (<5mm)
  • No tooth loss from periodontitis
Moderate Periodontal disease - Stage 2
  • Advanced periodontitis
  • Destruction of periodontal tissues beyond half the tooth length
  • Limited tooth loss has occurred & furcations and infra-bony pockets common
  • Treatment more complex & usually entails surgical intervention
Severe Periodontal disease - Stage 3
  • Severity & complexity are increased by an increase in tooth loss (>5 teeth) along with presence of masticatory dysfunction that usually requires complex multidisciplinary treatment beyond periodontal therapy
Very Severe Periodontal disease - Stage 4
Table 8. Overview of Grading (Rate of Progression & Risk Factors).
Grade Description
A Rate of progression low
No risk factors
B Expected progression
C Evident risk factors & high risk of progression