Each of the following is a recognized effect of smoking on the periodontium EXCEPT:

Correct answer: D. Increased gingival bleeding on probing

• A. Smoking impairs fibroblast function, attachment, and collagen production while increasing collagenase activity.
• B. Smoking is the strongest modifiable risk factor for periodontitis; smokers have significantly greater bone loss and deeper pockets.
• C. Smoking impairs neutrophil chemotaxis and phagocytosis, reduces oxygen delivery, and delays healing — a major reason for implant failure and poor graft outcomes.
• D. CORRECT — this is the EXCEPTION. Smokers show LESS bleeding on probing, not more. Nicotine causes peripheral vasoconstriction and chronic microvascular changes that MASK clinical signs of inflammation. This is a dangerous clinical trap: a smoker with minimal bleeding may still have advanced destruction underneath. Diagnose smokers on attachment loss and radiographic bone level, not on bleeding scores.

Note: Reduced bleeding in a smoker is not health — it is masked disease.