2017 AAP Periodontal Classification
Key Takeaways
- Periodontitis staging measures severity and complexity across 4 distinct levels (Stages I to IV) based on CAL, RBL, and tooth loss.
- Periodontitis grading predicts progression across 3 distinct levels (Grades A to C) using the RBL% divided by age ratio.
- Stage I and II represent initial to moderate disease with 0 teeth lost, while Stage III and IV represent severe disease with ≥1 teeth lost.
- Grade C represents rapid progression, indicated by bone-loss-to-age ratios over 1.0, smoking 10+ cigarettes daily, or HbA1c levels of 7.0% or greater.
- Complexity factors, such as vertical bone loss >= 3 mm or lack of posterior support, automatically shift staging to Stage III or IV.
2017 AAP Periodontal Classification
Introduction to the 2017 World Workshop Classification
In 2017, the American Academy of Periodontology (AAP) and the European Federation of Periodontology (EFP) updated the classification of periodontal and peri-implant diseases. This system replaced the 1999 classification, which separated 'chronic' and 'aggressive' periodontitis. The current system groups periodontitis into a single disease entity and characterizes it using a multidimensional Staging and Grading framework, similar to staging systems used in oncology.
- Staging: Identifies the severity and complexity of the disease based on past tissue destruction, as well as the complexity of long-term management.
- Grading: Predicts the future rate of disease progression, determines the patient's responsiveness to therapy, and assesses the impact of systemic risk factors.
Periodontitis Staging: Parameters and Complexity
Staging is determined by assessing the site of greatest interdental clinical attachment loss (CAL) due to periodontitis. If CAL is unavailable, radiographic bone loss (RBL) is utilized. The stage is further refined by complexity factors and tooth loss due to periodontal disease.
1. Stage I: Initial Periodontitis
- Severity:
- Interdental CAL: 1 to 2 mm at the site of greatest loss.
- Radiographic Bone Loss (RBL): Coronal third (<15% of the root length).
- Tooth Loss: 0 teeth lost due to periodontitis.
- Complexity: Maximum probing depth <= 4 mm; horizontal bone loss. No furcation or mobility issues.
2. Stage II: Moderate Periodontitis
- Severity:
- Interdental CAL: 3 to 4 mm at the site of greatest loss.
- Radiographic Bone Loss (RBL): Coronal third (15% to 33% of the root length).
- Tooth Loss: 0 teeth lost due to periodontitis.
- Complexity: Maximum probing depth <= 5 mm; horizontal bone loss. No furcation or mobility issues.
3. Stage III: Severe Periodontitis with Potential for Additional Tooth Loss
- Severity:
- Interdental CAL: >= 5 mm.
- Radiographic Bone Loss (RBL): Extending to the middle or apical third of the root (>=33%).
- Tooth Loss: <= 4 teeth lost due to periodontitis.
- Complexity: Max probing depth >= 6 mm; vertical bone loss >= 3 mm; Glickman Class II or III furcation involvement; moderate ridge defects.
4. Stage IV: Advanced Periodontitis with Potential for Loss of Dentition
- Severity:
- Interdental CAL: >= 5 mm.
- Radiographic Bone Loss (RBL): Extending to the middle or apical third (>=33%).
- Tooth Loss: >= 5 teeth lost due to periodontitis.
- Complexity: All Stage III complexity factors, plus masticatory dysfunction, secondary occlusal trauma (mobility Class II or III), bite collapse, drifting, and severe ridge defects. The patient has less than 20 remaining teeth (fewer than 10 opposing pairs).
Extent and Distribution:
After establishing the stage, the clinician describes the distribution:
- Localized: <30% of teeth are involved.
- Generalized: >=30% of teeth are involved.
- Molar-Incisor Pattern: Tissue destruction is restricted to the first molars and incisors (formerly known as localized juvenile periodontitis).
Periodontitis Grading: Rate of Progression and Risk Modifiers
Grading is established using primary criteria (direct or indirect evidence of progression) and is modified by systemic risk factors. A single worse indicator determines the final grade.
Primary Criteria:
- Direct Evidence: Longitudinal data showing clinical attachment loss (CAL) or radiographic bone loss (RBL) over a 5-year period.
- Grade A (Slow rate): No loss over 5 years.
- Grade B (Moderate rate): < 2 mm loss over 5 years.
- Grade C (Rapid rate): >= 2 mm loss over 5 years.
- Indirect Evidence: Calculated by dividing the percentage of radiographic bone loss (RBL) at the worst site by the patient's age:
Grading Ratio = RBL (% of root length) / Age
- Grade A (Slow rate): Ratio < 0.25. (e.g., a 60-year-old with 10% bone loss: 10 / 60 = 0.17).
- Grade B (Moderate rate): Ratio 0.25 to 1.0. (e.g., a 40-year-old with 20% bone loss: 20 / 40 = 0.50).
- Grade C (Rapid rate): Ratio > 1.0. (e.g., a 25-year-old with 30% bone loss: 30 / 25 = 1.20).
- Biofilm vs. Destruction Phenotype:
- Grade A: Heavy biofilm accumulation with low levels of tissue destruction.
- Grade B: Biofilm and destruction levels are commensurate.
- Grade C: Destruction exceeds expectations given the biofilm levels (aggressive patterns).
Grade Modifiers (Risk Factors):
Systemic risk factors act as multipliers, modifying the grade based on patient health habits or disease control.
- Smoking:
- Non-smoker: Grade A.
- Smoker < 10 cigarettes/day: Grade B.
- Smoker >= 10 cigarettes/day: Grade C.
- Diabetes Mellitus (HbA1c levels):
- No diabetes: Grade A.
- Well-controlled (HbA1c < 7.0%): Grade B.
- Poorly-controlled (HbA1c >= 7.0%): Grade C.
Clinical Rule for Grading:
If a patient has a primary criteria ratio of 0.40 (Grade B) but smokes 15 cigarettes a day (Grade C), the smoking modifier overrides the primary criteria, and the patient is classified as Grade C.
A 45-year-old patient exhibits interdental clinical attachment loss (CAL) of 4 mm at the site of greatest loss, with radiographic bone loss extending into the coronal third (approximately 25% of the root length). The patient has not lost any teeth due to periodontitis, and the maximum probing depth is 5 mm. What is the appropriate stage for this patient's periodontitis?
A 38-year-old patient presents with radiographic bone loss extending to the mid-root of multiple teeth (approximately 40% of the root length). Calculating the ratio of radiographic bone loss to age yields a value of 1.05. The patient also smokes 12 cigarettes per day. Which grade should be assigned to this patient's periodontal condition?
A patient is diagnosed with periodontitis. The clinician finds that the patient has lost 6 teeth due to periodontal disease, has interdental CAL of 6 mm, and exhibits a lack of posterior occlusal support (masticatory dysfunction) with fewer than 20 remaining teeth. Which stage best describes this clinical presentation?