A periodontal probe is the cheapest instrument in any dental clinic — and arguably the most diagnostically valuable. Pocket depths, attachment loss, bleeding indices, furcation involvement: every periodontal decision starts with a probe reading.
The trick: there isn't one universal probe. Five patterns dominate, each calibrated for a different reading. Below, what each probe measures and how to build a balanced charting kit.
TL;DR
UNC-15 = 1mm markings to 15mm. Best for detailed pocket charting. Williams = traditional 1, 2, 3, 5, 7, 8, 9, 10mm markings. WHO/CPITN = 0.5mm ball end + colour band 3.5–5.5mm. Used for screening (BPE/CPI). Naber's = curved, used to measure furcation involvement.
Probe pattern comparison
| Probe | Markings | Tip | Primary use | When to choose |
|---|---|---|---|---|
| UNC-15 | 1, 2, 3, 4, 5… up to 15mm | Tapered, pointed | Detailed periodontal charting | Comprehensive periodontal exams |
| UNC-12 | 1mm increments to 12mm | Tapered, pointed | Detailed charting (compact) | When 15mm is overkill |
| Williams | 1, 2, 3, 5, 7, 8, 9, 10mm (skipping 4 & 6) | Tapered, pointed | Traditional pocket measurement | Practices used to legacy charts |
| WHO / CPITN | 0.5mm ball + colour band 3.5–5.5mm | 0.5mm ball | BPE / CPI screening | NHS/PHE screening protocols |
| Naber's | 3, 6, 9, 12mm (curved) | Blunted, curved | Furcation involvement (Class I/II/III) | When recording molar furcations |
| Marquis (CP-12) | 3, 6, 9, 12mm colour bands | Tapered, pointed | Quick charting (US standard) | High-volume practices wanting speed |
ErgoDenta periodontal probes
All probes are designed for the silicone-handled ErgoLite or ErgoX® system — pick the handle that suits your workflow.
How to build a complete charting tray
For a comprehensive periodontal charting tray, three probes cover everything:
- UNC-15 — for primary 6-point pocket depth measurements
- WHO / CPITN ball-end — for screening exams (BPE), and safer use in pregnant or paediatric patients
- Naber's curved probe — for furcation involvement on molars
Add a CP-12 if your charting software uses 3/6/9/12mm colour zones for fast reading.
Probe technique — short reminders
- Walk the probe in 1mm steps along the tooth circumference
- Apply ~25g of force (about the weight of a 25¢ coin)
- Read at 6 points per tooth: MB, B, DB, ML, L, DL
- Record the deepest reading per site, not the average
- For BPE/CPI use a WHO probe — the ball end stops you over-probing
When the probe lies — common pitfalls
- Excessive force → overestimates pocket depth (perforates the junctional epithelium)
- Subgingival calculus → probe stops short → underestimated pocket
- Inflammation → tissue is more penetrable than usual → can overestimate by 0.5–1mm
- Probe angulation → not parallel to long axis → falsely shallow reading
Frequently asked questions
What's the difference between BPE and a full periodontal chart?
Can I use a UNC-15 instead of a WHO probe for BPE?
How often should I replace probes?
What's the best probe for paediatric patients?
Are colour-coded probes more accurate than markings?
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