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Williams periodontal probe

Also called: perio probe, Michigan O probe with Williams markings, Williams markings

A blunt, millimeter-marked rod used to measure gum pocket depth.

A periodontal probe is a ruler for the gums. It slides gently into the sulcus (the small space between tooth and gum) to measure pocket depth in millimeters. The Williams marking pattern has lines at 1, 2, 3, 5, 7, 8, 9 and 10 mm, with no marks at 4 and 6 mm, so the gaps help you count quickly.

How to spot it

  • A thin, round, blunt tip with dark bands or lines; no sharp point.
  • Marks at 1-2-3, then 5, then 7-8-9-10 mm (missing 4 and 6).
  • Probe vs. explorer: a probe has markings and a rounded end; an explorer is sharp and unmarked.

What it is used for

  • Six readings per tooth are recorded on the periodontal chart.
  • The assistant often records the numbers as the hygienist or dentist calls them out.

Safety and care

  • Critical item (it goes into soft tissue or touches bone): clean it, package it and heat-sterilize it after every patient.

Related

Sources: Ergodenta. Periodontal Probes Guide: UNC-15, Williams, WHO, Naber's & CPITN. ; UNC-15 product listing, Gehrig JS, Shin DE. Fundamentals of Periodontal Instrumentation and Advanced Root Instrumentation, 9th ed. Jones & Bartlett, 2023 (plus Newman & Carranza's Clinical Periodontology), CDC. Guidelines for Infection Control in Dental Health-Care Settings, 2003. MMWR 2003;52(RR-17)