Periodontal Examination: Probing, CPI and Russell's Index

A periodontal examination is the systematic measurement of gum health: probe depths around each tooth, attachment loss, bleeding, and tooth mobility. Standardised indices — notably the CPI and Russell’s Periodontal Index — turn these measurements into scores that diagnose disease and track it over time.

It matters because gum disease is painless until late, and only measurement reveals it. A probe reading of 3 mm versus 6 mm is the difference between health and disease needing surgery — and indices let clinicians and public-health programmes speak the same numerical language.

Key Concepts

• Probing depth (PD) — measured with a millimetre-marked probe at 6 sites per tooth. Healthy: 1–3 mm; 4–5 mm suggests early disease; 6 mm+ indicates advanced disease.
• Clinical attachment level (CAL) — probing depth adjusted for recession, measured from the fixed cementoenamel junction. CAL is the true record of destroyed support.
• Bleeding on probing (BOP) — bleeding within seconds of gentle probing signals active inflammation at that site.
• Mobility (Miller grades) — 0: normal; 1: barely perceptible; 2: visible movement up to 1 mm; 3: over 1 mm or vertical depressibility.
• Furcation involvement (Glickman I–IV) — bone loss between the roots of molars: I: early; II: partial entry; III: through-and-through; IV: through-and-through with visible recession.
• CPI (Community Periodontal Index) — WHO screening index per sextant: 0: healthy; 1: bleeding; 2: calculus; 3: 4–5 mm pocket; 4: 6 mm+ pocket (asterisk * marks furcation).
• Russell’s Periodontal Index — scores each tooth 0–8 (0: negative; 1: mild gingivitis; 2: gingivitis circumscribing the tooth; 6: pocket formation; 8: advanced destruction). The person’s score is the average of all teeth.

How It Works

1. Full-mouth probing. The probe is walked gently around every tooth at 6 sites; depths, recession, bleeding and suppuration are charted.
2. Attachment calculation. CAL is derived at each site, mapping the destroyed support.
3. Mobility and furcation. Each tooth is tested for movement; multi-rooted teeth are checked with a curved furcation probe.
4. Index scoring. The worst finding per sextant gives the CPI code; Russell’s tooth scores are averaged for surveys.
5. Diagnosis and plan. The numbers convert to a diagnosis and treatment plan, and re-probing after treatment measures the response objectively.

Worked Example

A screening of the upper-right sextant finds generalised bleeding, calculus on two teeth, and a 5 mm pocket on the first molar. The sextant takes its worst score — the 5 mm pocket outranks bleeding and calculus — so it scores CPI 3 (treatment need: deep cleaning). Separately, Russell’s scoring of a full mouth: 20 teeth score 1, 6 teeth score 2, 2 molars score 6. Sum = 20 + 12 + 12 = 44; ÷ 28 teeth = 1.57. A PI of ~1.6 means established gingivitis with early periodontitis — one number to compare at the next review.

Common Misconceptions

• “Probing is supposed to hurt.” A probe uses only about 25 g of force — like writing with a pencil. Pain usually means inflamed tissue, not rough technique.
• “One deep reading means surgery.” A single 5–6 mm site may resolve with deep cleaning; the pattern across the mouth decides the plan, not one number.
• “Indices are just academic.” CPI codes prescribe treatment needs directly (0–1: hygiene instruction, 2: scaling, 3–4: complex care), and surveys use them to direct public-health resources.

Real-World Applications

Periodontal examination underpins practice: new-patient assessments, 3-month re-evaluations after deep cleaning, implant monitoring, orthodontic clearance (teeth are not moved through active disease), documentation, and national oral-health surveys using CPI.

Recap: Probe every site, record attachment loss, note bleeding, grade mobility and furcations, then summarise with CPI or Russell’s scores. Numbers turn invisible disease into a visible, trackable, treatable condition.