Periodontal Diagnosis & Classification MCQ

Periodontal diagnosis is read with two instruments: the periodontal probe and the radiograph. The probe gives probing depth and bleeding on probing for inflammation, and clinical attachment level for the true structural loss; recession, mobility, and furcation involvement complete the clinical picture. The radiograph adds the bone level and the pattern of loss. All of this is then organized by the 2017 classification, which stages periodontitis I to IV by severity and complexity, grades it A to C by the rate of progression and risk, and describes its extent. The single most important measurement is clinical attachment level, because, unlike probing depth, it is anchored to a fixed landmark and reflects actual attachment loss.

The Periodontal Probe: Depth, Attachment, and Bleeding

• Probing depth (PD) is measured from the gingival margin to the base of the sulcus or pocket, and it depends on where the gingival margin sits (so swelling deepens it and recession reduces it).
• Clinical attachment level (CAL) is measured from the cementoenamel junction (a fixed landmark) to the base of the pocket; when the margin is apical to the CEJ, CAL equals probing depth plus recession.
• CAL is the better measure of true structural loss precisely because it does not change just because the gingival margin moves with swelling or recession.
• Bleeding on probing (BOP) indicates inflammation at a site; its absence is a strong predictor of periodontal stability, while its presence flags ongoing inflammation. Each tooth is probed at six sites (mesiobuccal, buccal, distobuccal, mesiolingual, lingual, distolingual).

Recession, Mobility, and Furcation

• Gingival recession is measured from the cementoenamel junction to the gingival margin; it exposes root surface and adds to the attachment loss captured by CAL.
• Tooth mobility is graded (commonly the Miller classification): Class 1 is slightly increased horizontal mobility, Class 2 is greater horizontal mobility, and Class 3 adds vertical (depressible) mobility, the most severe.
• Furcation involvement is loss of bone and attachment in the area between the roots of a multirooted tooth, graded (Glickman) I to IV: Grade I is incipient, Grade II is a definite horizontal defect that does not pass through, Grade III is through-and-through but covered by soft tissue, and Grade IV is through-and-through and clinically visible.
• Furcation involvement worsens prognosis because the furcation is difficult to clean and instrument, and through-and-through (Grade III to IV) lesions are particularly hard to maintain.

Radiographic Assessment

• On a healthy radiograph, the alveolar crest sits roughly 1 to 2 mm apical to the cementoenamel junction; greater distances indicate bone loss.
• Horizontal bone loss is a generalized reduction in crestal height roughly parallel to the CEJ; vertical (angular) bone loss is an infrabony defect along one surface of a tooth, producing an angular pattern.
• Furcation involvement may appear as a radiolucency in the furca, and overall the radiograph helps gauge the bone level and the crown-to-root ratio.
• The radiograph has real limits: it is two-dimensional, it tends to underestimate bone loss, it cannot show the buccal and lingual plates well, and it does not measure soft-tissue attachment, so it is always read alongside probing.

The 2017 Classification: Staging and Grading

• The 2017 classification stages periodontitis I to IV by severity and complexity, using interdental clinical attachment loss and radiographic bone loss, plus tooth loss due to periodontitis and the complexity of rehabilitation needed.
• Stage I is initial periodontitis; Stage II is moderate; Stage III is severe with potential for additional tooth loss; Stage IV is advanced, with extensive tooth loss and complex rehabilitation needs.
• Grading (A, B, C) describes the rate of progression and risk: it uses a proxy such as the percentage of bone loss divided by the patient's age, modified by risk factors (smoking and diabetes), with Grade A slow, Grade B moderate, and Grade C rapid.
• Extent is described as localized (under 30 percent of sites involved), generalized (30 percent or more), or molar-incisor pattern; staging is set by the worst affected site and is not reduced by treatment.

Health, Gingivitis, and the Periodontitis Case Definition

• Periodontal health is the absence of inflammation (no bleeding on probing) with no attachment loss; after successful treatment a patient may have stable but reduced attachment, which is health on a reduced periodontium, not the same as an untreated intact periodontium.
• Plaque-induced gingivitis is inflammation (bleeding on probing) without attachment loss, and it is reversible.
• The 2017 case definition of periodontitis requires detectable interdental clinical attachment loss at two or more non-adjacent teeth (or buccal/lingual attachment loss of 3 mm or more with pocketing at two or more teeth) not explained by non-periodontal causes.
• Distinguishing true periodontitis from localized recession or a non-periodontal cause matters, because the diagnosis sets the treatment intensity and the maintenance plan.