Teeth Whitening Teeth Whitening 3 — Questions and Answers
Question 1: Which type of tooth discoloration CANNOT be corrected by bleaching agents?
- Coffee and tea stains
- Tobacco stains on enamel surface
- Discoloration from a dead (non-vital) tooth (Correct answer)
- Age-related yellowing of enamel
Correct answer: Discoloration from a dead (non-vital) tooth
Non-vital (dead) teeth require internal bleaching or restorative options because external bleaching agents cannot penetrate to the source of the discoloration.
Question 2: What does 'walking bleach' technique refer to in dentistry?
- Applying whitening gel while the patient exercises
- Placing bleaching agent inside a root-treated tooth between appointments (Correct answer)
- Using portable LED devices during daily activities
- Gradually increasing peroxide concentration over weeks
Correct answer: Placing bleaching agent inside a root-treated tooth between appointments
The walking bleach technique involves sealing a bleaching agent inside the pulp chamber of a non-vital tooth to whiten it between dental visits.
Question 3: Which shade guide is most commonly used by dentists to objectively measure whitening progress?
- Munsell color system
- VITA classical shade guide (Correct answer)
- Pantone dental chart
- NBS color index
Correct answer: VITA classical shade guide
The VITA classical shade guide is the industry standard used to assess and document tooth color before and after whitening.
Question 4: Dental veneers placed before whitening can cause a cosmetic problem because:
- Veneers weaken surrounding enamel during bleaching
- Veneers do not respond to bleaching and will appear darker than whitened natural teeth (Correct answer)
- Whitening gel dissolves veneer bonding resin
- Veneers increase sensitivity to peroxide
Correct answer: Veneers do not respond to bleaching and will appear darker than whitened natural teeth
Porcelain and composite veneers do not bleach, so if natural teeth are whitened afterward, the veneers will appear mismatched and darker by comparison.
Question 5: At what concentration does hydrogen peroxide in whitening products typically require a prescription or dental supervision in the US?
- Above 1%
- Above 3%
- Above 6% (Correct answer)
- Above 35%
Correct answer: Above 6%
Products containing more than 6% hydrogen peroxide are generally classified as requiring dental supervision or a prescription in many regulatory frameworks.
Question 6: Which patient would be the LEAST suitable candidate for teeth whitening?
- A 25-year-old with extrinsic coffee stains
- A 14-year-old whose permanent teeth have fully erupted
- A 30-year-old who is 6 months pregnant (Correct answer)
- A 40-year-old with mild fluorosis
Correct answer: A 30-year-old who is 6 months pregnant
Pregnant women are advised to postpone elective whitening procedures due to a lack of safety data and the principle of avoiding unnecessary chemical exposure during pregnancy.
Question 7: How does potassium nitrate reduce whitening-induced tooth sensitivity?
- It blocks the peroxide from entering dentinal tubules
- It coats enamel with a protective film
- It calms the pulp nerve by depolarizing nerve fibers (Correct answer)
- It neutralizes the pH of bleaching gel
Correct answer: It calms the pulp nerve by depolarizing nerve fibers
Potassium nitrate penetrates to the nerve and depolarizes (desensitizes) the nerve fibers, reducing the transmission of pain signals.
Teeth Whitening Teeth Whitening 3
Which type of tooth discoloration CANNOT be corrected by bleaching agents?