Teeth Whitening Knowledge 4 — Questions and Answers
Question 1: Which food and beverage is considered one of the MOST significant contributors to extrinsic tooth staining?
- Orange juice
- Milk
- Red wine (Correct answer)
- Sparkling water
Correct answer: Red wine
Red wine contains tannins and chromogens that adhere strongly to enamel, making it one of the top staining culprits.
Question 2: What is 'rebound' in the context of teeth whitening?
- An allergic reaction to whitening gel
- Gradual return of tooth color toward the pre-whitening shade over time (Correct answer)
- Sudden increase in tooth sensitivity after bleaching
- Enamel erosion caused by repeated whitening
Correct answer: Gradual return of tooth color toward the pre-whitening shade over time
Rebound refers to the natural tendency of whitened teeth to gradually re-darken over months to years as new stains accumulate and initial hydration changes reverse.
Question 3: Which of the following is a common characteristic of enamel fluorosis that affects whitening outcomes?
- It creates deep brown intrinsic stains that respond fully to standard bleaching
- It may cause white spots or mottling that become more noticeable after whitening (Correct answer)
- It always requires porcelain veneers instead of bleaching
- It causes hypersensitivity that makes all whitening contraindicated
Correct answer: It may cause white spots or mottling that become more noticeable after whitening
Whitening can intensify the contrast between fluorotic white spots and surrounding enamel, potentially making the spots look more obvious.
Question 4: At what approximate pH does hydrogen peroxide become most chemically active for bleaching purposes?
- pH 2–3 (strongly acidic)
- pH 5–6 (mildly acidic)
- pH 9–11 (alkaline) (Correct answer)
- pH 13–14 (strongly alkaline)
Correct answer: pH 9–11 (alkaline)
Hydrogen peroxide releases free radicals most effectively in an alkaline environment (pH 9–11), which is why many whitening gels are buffered to this range.
Question 5: What is the main concern with overusing whitening products beyond recommended durations?
- Permanent darkening of the dentin
- Enamel erosion and structural weakening (Correct answer)
- Increased risk of cavities only
- The teeth stop responding to peroxide permanently
Correct answer: Enamel erosion and structural weakening
Excessive or overly frequent whitening can erode enamel structure over time, leading to increased sensitivity and vulnerability to damage.
Question 6: Which dental restorations do NOT respond to hydrogen peroxide whitening?
- Natural enamel
- Dentin below enamel
- Porcelain crowns and composite fillings (Correct answer)
- All tooth surfaces respond equally
Correct answer: Porcelain crowns and composite fillings
Dental restorations such as porcelain crowns, veneers, and composite resin fillings do not change color with peroxide bleaching agents.
Question 7: Which professional whitening system is designed to be used by the patient at home under dentist supervision using custom trays and lower-concentration gel?
- In-office power bleaching
- Dentist-dispensed take-home whitening (Correct answer)
- Over-the-counter whitening strips
- Charcoal toothpaste whitening
Correct answer: Dentist-dispensed take-home whitening
Dentist-dispensed take-home kits provide custom trays and professionally formulated gel for supervised home use, balancing convenience with effectiveness.
Teeth Whitening Knowledge 4
Which food and beverage is considered one of the MOST significant contributors to extrinsic tooth staining?