Restorative & Materials · patient case question
What is the MOST likely explanation for the pattern of caries?
Patient case: Rampant interproximal caries in a smoker who chews mints
Patient: Male, 34 years old
Chief Complaint: “I keep getting cavities between my teeth even though I brush.”
Background: Smokes half a pack a day. Reports brushing twice daily with a fluoride toothpaste. Uses sugar-containing breath mints continuously through the working day to mask the smell of smoke.
Current Findings: Carious lesions on virtually every interproximal surface. Diffuse brown-black pigmentation distributed symmetrically along the attached gingiva of both arches, unchanged for as long as he can remember.
Show answer and explanation
Correct answer: C. Continuous exposure to fermentable carbohydrate from the mints
- A. He is using fluoride toothpaste twice daily. Fluoride shifts the demineralisation-remineralisation balance, but it cannot compensate for a near-continuous acid challenge.
- B. He brushes twice daily, and brushing does not reach interproximal surfaces effectively in any case. Technique is not the governing variable here.
- C. CORRECT. What drives caries is not the QUANTITY of sugar but the FREQUENCY of exposure. A mint every twenty minutes keeps plaque pH below the critical value almost continuously, leaving no time for salivary buffering and remineralisation between challenges. Interproximal surfaces are the least self-cleansing and least accessible to a toothbrush, so they cavitate first — which is exactly the pattern seen.
- D. Smoking does reduce salivary flow and is an independent caries risk factor, but it does not explain why the lesions are specifically and uniformly interproximal. The mints do.
Note: Counsel on frequency, not just amount: swap to xylitol-containing or sugar-free mints, cluster any sugar intake with meals, add interproximal cleaning, and layer in high-concentration fluoride. Smoking cessation is a separate but linked conversation.
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