Teeth Whitening Knowledge 2 — Questions and Answers
Question 1: Which chemical compound is the primary active ingredient in most professional teeth whitening gels?
- Sodium fluoride
- Hydrogen peroxide (Correct answer)
- Calcium carbonate
- Potassium nitrate
Correct answer: Hydrogen peroxide
Hydrogen peroxide is the active bleaching agent in most professional whitening gels, oxidizing stain molecules within enamel.
Question 2: What is the typical concentration range of carbamide peroxide found in over-the-counter whitening strips?
- 1–5%
- 10–22% (Correct answer)
- 35–40%
- 45–50%
Correct answer: 10–22%
OTC whitening strips generally contain 10–22% carbamide peroxide, which is lower than professional in-office concentrations.
Question 3: Teeth whitening primarily works on which layer of the tooth?
- Cementum
- Dentin
- Enamel (Correct answer)
- Pulp
Correct answer: Enamel
Whitening agents penetrate the enamel to oxidize chromogens, although they can also affect underlying dentin to some extent.
Question 4: Which type of tooth discoloration is generally considered most responsive to bleaching treatment?
- Intrinsic gray discoloration from tetracycline
- Fluorosis white spots
- Extrinsic yellow stains from food and drink (Correct answer)
- Developmental enamel defects
Correct answer: Extrinsic yellow stains from food and drink
Extrinsic yellow stains caused by dietary chromogens respond best to whitening because they sit at or near the enamel surface.
Question 5: How does light or laser activation help in professional in-office whitening?
- It bonds the whitening gel permanently to enamel
- It kills bacteria that cause discoloration
- It accelerates the decomposition of peroxide to release more oxygen radicals (Correct answer)
- It remineralizes the enamel after bleaching
Correct answer: It accelerates the decomposition of peroxide to release more oxygen radicals
Light energy accelerates the breakdown of hydrogen peroxide into free radicals, which speeds up the oxidation of stain molecules.
Question 6: What is the recommended post-whitening 'white diet' period intended to prevent?
- Tooth fracture from hard foods
- Re-staining of temporarily porous enamel (Correct answer)
- Allergic reactions to whitening agents
- Gum tissue overgrowth
Correct answer: Re-staining of temporarily porous enamel
After whitening, enamel pores are temporarily open, making teeth more susceptible to picking up new chromogens from pigmented foods.
Question 7: Which patients are typically advised AGAINST teeth whitening procedures?
- Adults with mild enamel fluorosis
- Patients with large composite resin restorations on front teeth
- Pregnant or breastfeeding women (Correct answer)
- Adults over the age of 50
Correct answer: Pregnant or breastfeeding women
Whitening is contraindicated during pregnancy and breastfeeding due to insufficient safety data on fetal and infant exposure.
Teeth Whitening Knowledge 2
Which chemical compound is the primary active ingredient in most professional teeth whitening gels?