Periodontal Probes: Williams, CP-12, WHO & Nabers Explained

What a periodontal probe measures

A periodontal probe is a slim, blunt, calibrated instrument used to measure the depth of the gingival sulcus or periodontal pocket in millimetres. Gentle, accurate probing around each tooth is the foundation of a periodontal examination, helping to detect pocketing, bleeding, recession and loss of attachment.

Williams probe

The Williams probe is a classic design with circumferential markings at 1, 2, 3, 5, 7, 8, 9 and 10 mm (the 4 and 6 mm lines are omitted to reduce confusion). It remains a widely taught, general-purpose probe.

CP-12 and CP-15 UNC probes

Colour-coded probes such as the CP-12 have a banded section (for example, 3–6–9–12 mm) that makes reading pocket depths quick and easy. The CP-15 UNC is marked at every millimetre up to 15 mm, with colour banding, for detailed recording. These probes speed up charting and improve consistency between clinicians.

WHO / CPITN ball-tip probe

The WHO (CPITN) probe has a small 0.5 mm ball at the tip and a coloured band, usually from 3.5 to 5.5 mm. The ball tip is atraumatic and helps detect subgingival calculus, while the band is used for screening indices. It is the standard probe for community periodontal screening.

Nabers furcation probe

The Nabers probe is curved so it can reach horizontally between the roots of multi-rooted teeth to detect and grade furcation involvement. Colour-coded versions allow the depth of furcation defects to be recorded.

Choosing a probe

Many clinicians keep a colour-coded straight probe for routine charting, a WHO probe for screening and a Nabers probe for furcations. Probes should be checked for a clear, undamaged tip and replaced when markings wear. Titanium probes are also available for use around implants.

See our full range of periodontal probes and explorers.