Pharmacology · single question
Which active ingredient in some mouthwashes is responsible for causing tooth staining that can only be removed by professional prophylaxis?
Show answer and explanation
Correct answer: D. Cetylpyridinium chloride (CPC)
Cetylpyridinium chloride (CPC) is a quaternary ammonium compound antiseptic used in mouthwashes. Like chlorhexidine, CPC can cause extrinsic tooth staining (brown/yellow) that binds to the pellicle and requires professional prophylaxis for complete removal. Chlorhexidine is the most well-known staining agent, but CPC causes a similar though usually milder effect.
- A. Hydrogen peroxide in whitening mouthwashes has a bleaching effect — it lightens rather than stains teeth.
- B. Xylitol is an antibacterial sugar alcohol; it does not cause tooth staining.
- C. Fluoride does not cause tooth staining at therapeutic concentrations in mouthwashes.
- D. CORRECT. Cetylpyridinium chloride (CPC) is the mouthwash ingredient known to cause extrinsic tooth staining that binds to the dental pellicle and requires professional prophylaxis for removal.