Which of the following is a sign of periodontal disease when probing?

• A. Bleeding/suppuration/inflammation
• B. Rolled, red gingiva
• C. 4mm+ probing depths
• D. Probe touches roots below CEJ

Answer: (C)

Probing depth is a direct measure of pocket formation. Normal sulcus depth is about 1–3 mm; when a measurement reaches 4 mm or more, it signifies a periodontal pocket resulting from detachment of the gingival fibers and apical migration of the junctional epithelium. This reflects attachment loss and underlying bone changes, a clear sign of periodontal disease when assessed by probing.

Bleeding on probing shows gingival inflammation but isn’t itself a definitive sign of disease severity or pocketing. Rolled, red gingiva also indicates inflammation rather than a probing-detected pocket. Touching roots below the CEJ suggests recession or exposure of root surfaces, which can occur with or without active pocketing and doesn’t directly indicate probing-detected periodontal disease. Thus, 4 mm or greater probing depth is the best indicator among these options.