A smoker presents with multiple interproximal carious lesions. He reports sucking on mints throughout the day. What is the MOST likely explanation for his caries pattern?

Correct answer: B. Frequent exposure to fermentable carbohydrate from the mints

• A. ❌ Smoking is associated with periodontal disease and root caries via other pathways, but tobacco smoke is not directly cariogenic in the way sugar is.
• B. ✅ CORRECT — FREQUENCY of sugar exposure matters far more than total quantity. Each mint restarts the Stephan curve, dropping plaque pH below 5.5 for 20–40 minutes. Continuous sucking through the day means the mouth almost never returns to a neutral, remineralizing state — and interproximal surfaces, where clearance is slowest, suffer first.
• C. ❌ Nicotine does not interfere with fluoride uptake by enamel.
• D. ❌ Increased salivary flow would be PROTECTIVE. The problem is the sugar substrate, not the flow.

Note: Always ask about the vehicle AND the frequency: mints, cough drops, sweetened coffee, sports drinks, sipping soda. Sugar-free xylitol mints would be a reasonable substitution.