A patient with poor oral hygiene smokes 60 cigarettes/day, is an IV drug user, and needs a break every 20 minutes to smoke. Exam shows heavy plaque and loss of interdental papillae. Most likely diagnosis?

Correct answer: C. Necrotizing ulcerative periodontitis

• A. Chronic periodontitis progresses slowly and lacks the punched-out, necrotic, painful papillae seen here.
• B. Aggressive periodontitis features rapid attachment loss in otherwise healthy young patients with relatively little plaque — not this heavy-plaque, immunocompromised picture.
• C. Correct. Heavy smoking, immunosuppression/IV drug use, poor hygiene, and necrosis/loss of interdental papillae (cratered, 'punched-out' papillae) point to necrotizing ulcerative periodontitis.
• D. Gingivitis is reversible inflammation with no attachment/papilla loss — the necrosis here exceeds gingivitis.