A patient has numerous interproximal carious lesions. He is a smoker and reports constantly chewing mints throughout the day. What is the MOST likely reason for his caries?

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

• A. CORRECT. FREQUENCY of fermentable carbohydrate exposure is a more powerful caries determinant than total quantity. Each mint drops plaque pH below the critical threshold of 5.5, and the pH takes 20–40 minutes to recover (the Stephan curve). Continuous mint consumption means the tooth surface is essentially never allowed to recover, producing a net demineralization balance and rapid, widespread caries.
• B. Smoking is the strongest modifiable risk factor for PERIODONTAL disease and oral cancer, but it is not a direct primary cause of caries (though smoking-associated xerostomia contributes).
• C. Poor flossing removes a protective factor but does not by itself supply the acid challenge; frequent sugar is the driver.
• D. Genetics contributes modestly to caries susceptibility but cannot explain a change of this magnitude when a clear behavioural cause is present.

Note: Counsel on FREQUENCY first, then quantity. Sugar-free xylitol mints are an easy substitution that reverses the problem.