Periodontal Examination, Diagnosis, and Classification
What this domain tests
You must examine systematically, record periodontal parameters, and apply the 2018 AAP/EFP classification. The exam tests staging, grading, extent, and the difference between screening and definitive diagnosis.
Examination sequence
- Extraoral and intraoral soft-tissue inspection; plaque and bleeding scores.
- Probing depth at six sites per tooth, recession, CAL, furcation, mobility, and mucogingival involvement.
- Radiographs for bone level and pattern; bitewings for crestal bone, periapicals for furcations and apices.
- Risk assessment: smoking, HbA1c, medication, and genetics.
Classification rules
- Stage I: CAL 1–2 mm, bone loss coronal third under 15%, no tooth loss from periodontitis.
- Stage II: CAL 3–4 mm, bone loss 15–33%, no tooth loss.
- Stage III: CAL 5 mm or more, bone loss middle third or beyond, 4 or fewer teeth lost.
- Stage IV: CAL 5 mm or more, bone loss middle third or beyond, 5 or more teeth lost, plus complexity such as masticatory dysfunction or fewer than 20 teeth.
- Extent: localized under 30%, generalized 30% or more, molar–incisor pattern.
- Grade: A bone loss/age under 0.25; B 0.25–1.0; C over 1.0. Smoking 10 or more per day and HbA1c 7.0% or more upgrade to C.
Worked example
A 52-year-old has worst CAL 6 mm, 55% bone loss, two teeth lost to periodontitis, and smokes 15 per day. Bone loss/age = 55/52 = 1.06, so Grade C. CAL of 5 mm or more with middle-third bone loss and 4 or fewer teeth lost is Stage III. The diagnosis is Stage III, Grade C, generalized periodontitis.
Traps
- Using mean bone loss instead of the worst site.
- Grading on plaque scores rather than bone loss/age and modifiers.
- Forgetting that Stage IV requires tooth loss or complexity, not just deep pockets.