Tooth Discoloration & Bleaching

Q: A classic cause of intrinsic discoloration is:

Tetracycline. Tetracycline incorporated during development causes intrinsic staining.

Q: The walking bleach technique uses:

Sodium perborate in the pulp chamber. Walking bleach places sodium perborate in non-vital teeth.

Q: Home bleaching commonly uses:

10% carbamide peroxide. Home bleaching typically uses ~10% carbamide peroxide in trays.

⭐ High-Yield Facts for Exam

Extrinsic = surface; intrinsic = within tooth.
Tetracycline = classic intrinsic stain.
In-office vital = ~35% H2O2.
Home = ~10% carbamide peroxide.
Walking bleach = sodium perborate (non-vital).

Discoloration

Extrinsic — surface stains (tea, coffee, tobacco, chromogenic bacteria).
Intrinsic — within tooth structure; tetracycline staining is a classic cause; also fluorosis, pulp necrosis, dentinogenesis imperfecta.

Bleaching

In-office (vital) — higher concentration hydrogen peroxide (often ~35%).
Home (vital) — carbamide peroxide (commonly ~10%) in trays.
Walking bleach (non-vital) — sodium perborate placed in the pulp chamber of an endodontically treated, discoloured tooth.

Mechanism: peroxide releases free radicals that break down chromogens. Transient sensitivity is the common side effect.

Exam Tips ⭐

Tetracycline = classic intrinsic stain; walking bleach (sodium perborate) for non-vital teeth; in-office = 35% H2O2.

📝 Practice MCQs — Tooth Discoloration & Bleaching

Q1. A classic cause of intrinsic discoloration is:

A. Coffee

B. Tetracycline

C. Tobacco

D. Chromogenic bacteria

Show Answer

✅ Answer: B

Tetracycline incorporated during development causes intrinsic staining.

Q2. The walking bleach technique uses:

A. 35% H2O2 in office

B. Sodium perborate in the pulp chamber

C. 10% carbamide peroxide trays

D. Microabrasion

Show Answer

✅ Answer: B

Walking bleach places sodium perborate in non-vital teeth.

Q3. Home bleaching commonly uses:

A. 35% hydrogen peroxide

B. 10% carbamide peroxide

C. Sodium perborate

D. Phosphoric acid

Show Answer

✅ Answer: B

Home bleaching typically uses ~10% carbamide peroxide in trays.

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⭐ High-Yield Facts for Exam