A clinical intraoral photograph shows mildly red, slightly enlarged gingiva throughout the mouth. Probing reveals depths of 2–3 mm, with bleeding on probing (BOP) at 40% of sites. No bone loss is visible on radiographs. What is the periodontal diagnosis?

Correct answer: C. Generalized plaque-induced gingivitis

• A. Stage II periodontitis requires bone loss and CAL beyond Stage I thresholds. Not present here.
• B. Stage I periodontitis requires INTERDENTAL CAL ≥1mm at ≥2 non-adjacent teeth. Without radiographic bone loss or CAL, this is not periodontitis.
• C. CORRECT. Gingivitis is characterized by gingival inflammation (BOP, erythema) WITHOUT loss of clinical attachment or alveolar bone. Probing depths of 2–3 mm are within the normal range of sulcus depth. BOP at 40% of sites with no bone loss = GENERALIZED PLAQUE-INDUCED GINGIVITIS on an intact periodontium (per 2017 World Workshop classification: generalized = ≥30% of sites affected).
• D. The modifier 'on intact periodontium' is part of the full classification but the primary diagnosis is GENERALIZED plaque-induced gingivitis (not 'slight' — 40% BOP makes it generalized).