Williams probes are marked with mm intervals of up to 10mm. Williams probe lacks markings at 4 and 6 millimeters. These missing millimeter intervals aid in determining depth in minute situations. The ideal gingival pocket depth is about 3 to 4 mm. A William's probe lacks the 4 mm and 6 mm distinction required for a clear perception. When the periodontal probe is put within the gingiva... https://new-medinstruments.com/williams-dental-probe.html