Pathology · single question
Which component found in some mouthwashes causes tooth staining with long-term use?
Show answer and explanation
Correct answer: A. Cetylpyridinium chloride (CPC)
- A. Cetylpyridinium chloride (CPC) is a quaternary ammonium antiseptic found in many commercial mouthwashes (e.g., Scope, Cepacol). It can cause brownish tooth staining with prolonged use, though to a lesser extent than chlorhexidine. This is the specific ingredient being tested. ✓
- B. Sodium bicarbonate is an abrasive/buffering agent in some oral products and does not cause intrinsic staining.
- C. Sodium fluoride is an anti-caries agent in mouthwashes and does not cause significant tooth staining.
- D. Chlorhexidine gluconate is the classic cause of brown-black tooth staining with long-term use — this is the most well-known mouthwash staining agent. However, this question specifically asks about CPC.