Teeth Whitening Knowledge 5 — Questions and Answers
Question 1: What role does salivary enzyme catalase play during teeth whitening?
- It boosts hydrogen peroxide activity in enamel
- It breaks down hydrogen peroxide, reducing its whitening effectiveness (Correct answer)
- It protects tooth enamel from peroxide damage
- It deposits minerals onto enamel during bleaching
Correct answer: It breaks down hydrogen peroxide, reducing its whitening effectiveness
Catalase in saliva rapidly degrades hydrogen peroxide into water and oxygen, which is why controlling saliva contact with the gel is important.
Question 2: Which of the following best describes 'chromogens' in the context of tooth staining?
- Minerals that naturally make teeth yellow
- Highly pigmented organic compounds that adhere to tooth surfaces (Correct answer)
- Bacteria that produce acid causing enamel erosion
- Proteins in dentin that darken with age
Correct answer: Highly pigmented organic compounds that adhere to tooth surfaces
Chromogens are intensely colored organic molecules found in foods and beverages that bind to enamel pellicle and cause extrinsic staining.
Question 3: A patient reports their teeth appear slightly more translucent at the edges after repeated whitening. What does this suggest?
- Successful whitening — translucency is a sign of clean enamel
- Over-bleaching leading to enamel thinning (Correct answer)
- Remineralization of the enamel surface
- A normal optical effect from dehydration only
Correct answer: Over-bleaching leading to enamel thinning
Increased translucency at incisal edges often indicates enamel thinning from excessive whitening, which can be irreversible.
Question 4: How long after professional in-office whitening should patients typically wait before consuming staining foods and beverages?
- 10 minutes
- 1–2 hours
- 24–48 hours (Correct answer)
- 7 days
Correct answer: 24–48 hours
Enamel pores remain open and more susceptible to staining for approximately 24–48 hours following whitening, so patients should avoid chromogenic foods during this window.
Question 5: Which whitening method has the LONGEST lasting results, according to clinical evidence?
- Whitening toothpaste used twice daily
- Single in-office laser whitening session
- Professionally supervised take-home tray whitening over 2–4 weeks (Correct answer)
- Whitening chewing gum
Correct answer: Professionally supervised take-home tray whitening over 2–4 weeks
Extended take-home tray whitening over several weeks produces deeper penetration and longer-lasting results compared to a single in-office session.
Question 6: What is a possible consequence of placing whitening gel on cracked or chipped enamel?
- Enhanced whitening of the damaged area
- Peroxide penetration into the pulp causing pain or pulpitis (Correct answer)
- The gel simply does not adhere and washes away
- The crack seals itself due to the gel's oxidizing action
Correct answer: Peroxide penetration into the pulp causing pain or pulpitis
Cracks or chips allow peroxide to bypass enamel and dentin barriers, reaching the pulp and potentially causing significant pain or pulp irritation.
Question 7: Which of the following statements about natural aging and tooth color is accurate?
- Teeth naturally become whiter as enamel thickens with age
- Teeth darken with age as enamel thins and yellower dentin becomes more visible (Correct answer)
- Aging does not significantly affect tooth color
- Dentin lightens in color as people get older
Correct answer: Teeth darken with age as enamel thins and yellower dentin becomes more visible
As enamel gradually wears and thins over a lifetime, the deeper, more yellow dentin becomes more visible, causing teeth to appear darker.
Teeth Whitening Knowledge 5
What role does salivary enzyme catalase play during teeth whitening?