Teeth Whitening Whitening Ingredients & Chemistry 1 — Questions and Answers
Question 1: What is the active bleaching agent in most professional teeth whitening gels?
- Hydrogen peroxide (Correct answer)
- Sodium fluoride
- Calcium carbonate
- Baking soda
Correct answer: Hydrogen peroxide
Hydrogen peroxide is the primary active bleaching agent that penetrates enamel to oxidize and break apart stain molecules.
Question 2: Carbamide peroxide breaks down into which two compounds when applied to teeth?
- Hydrogen peroxide and urea (Correct answer)
- Sodium peroxide and carbon dioxide
- Calcium peroxide and ammonia
- Zinc peroxide and water
Correct answer: Hydrogen peroxide and urea
Carbamide peroxide decomposes into hydrogen peroxide (the active bleaching agent) and urea, which acts as a stabilizer.
Question 3: A 35% carbamide peroxide gel is approximately equivalent in whitening strength to what percentage of hydrogen peroxide?
- 10–12% (Correct answer)
- 17–18%
- 20–22%
- 30–32%
Correct answer: 10–12%
Carbamide peroxide is roughly one-third as potent as hydrogen peroxide, so 35% carbamide ≈ 10–12% hydrogen peroxide.
Question 4: Which ingredient is commonly added to whitening gels to reduce tooth sensitivity during treatment?
- Potassium nitrate (Correct answer)
- Titanium dioxide
- Silica abrasive
- Chlorhexidine
Correct answer: Potassium nitrate
Potassium nitrate depolarizes nerve fibers in the dentinal tubules, reducing the pain signal associated with whitening sensitivity.
Question 5: Fluoride is often included in whitening trays or post-whitening treatments primarily to do what?
- Remineralize enamel and reduce sensitivity (Correct answer)
- Accelerate bleaching action
- Neutralize peroxide residue
- Whiten additional surface stains
Correct answer: Remineralize enamel and reduce sensitivity
Fluoride helps remineralize the enamel surface temporarily weakened during bleaching and reduces post-treatment sensitivity.
Question 6: Which whitening mechanism do abrasive whitening toothpastes primarily use compared to peroxide-based gels?
- Physical removal of surface stains (Correct answer)
- Chemical oxidation of chromogens
- Enzymatic breakdown of proteins
- UV-light activation of pigments
Correct answer: Physical removal of surface stains
Abrasive toothpastes rely on mechanical scrubbing to polish away extrinsic surface stains rather than penetrating enamel to bleach intrinsic stains.
Teeth Whitening Whitening Ingredients & Chemistry 1
What is the active bleaching agent in most professional teeth whitening gels?