Nicotine from cigarettes has a direct effect on periodontal disease primarily by:

Correct answer: B. Causing vasoconstriction and impairing immune response

• A. Nicotine does not directly dissolve bone — it impairs the biological response to bacterial challenge.
• B. Correct. Nicotine causes vasoconstriction, which masks the clinical signs of inflammation (reduced bleeding on probing despite active disease). It also impairs neutrophil and fibroblast function, reducing the immune response and tissue healing capacity.
• C. Nicotine does not directly lower salivary pH.
• D. Nicotine does not directly increase plaque — it affects the host response to plaque.