Dental
Teeth Whitening: What Actually Works and What Doesn't
Haute MD Editorial Team
Teeth whitening works by using peroxide-based bleaching agents (hydrogen peroxide or carbamide peroxide) to oxidize and break down chromogens — the colored molecules responsible for tooth discoloration — within the enamel and dentin. Professional whitening (in-office or dentist-dispensed take-home trays) uses higher peroxide concentrations than OTC products, producing faster and more dramatic results. The degree of whitening depends on the cause and depth of discoloration — surface stains respond best, while intrinsic discoloration (tetracycline staining, fluorosis) responds less predictably.
In-office vs. take-home vs. OTC whitening
In-office whitening (Zoom, KöR) — 35-40% hydrogen peroxide applied chairside with light or heat activation, producing immediate results in one 60-90 minute appointment. Significant whitening in a single visit — ideal for events with close timelines. Cost $500-$1,000. Dentist-dispensed take-home trays — custom-fitted trays with 10-22% carbamide peroxide worn nightly for 1-2 weeks. Results equivalent or superior to in-office with lower chair time and cost ($300-$500). Most cosmetic dentists consider this the gold standard for long-term results. OTC products (Crest Whitestrips, whitening toothpaste, whitening pens) — 3-10% hydrogen peroxide with generic fit — produce modest improvement at lower cost. Best for maintenance of professional whitening results.
What causes tooth staining and what whitens it
Extrinsic staining (surface stains on enamel) — caused by coffee, tea, red wine, tobacco, and dark foods. Responds very well to professional whitening. Intrinsic staining (within the dentin layer) — caused by tetracycline antibiotics (taken during tooth development in childhood), excessive fluoride (fluorosis), trauma, aging, and certain medications. Responds more slowly and less completely to whitening — may require multiple professional treatments, veneers, or bonding for optimal correction. Age-related yellowing — a combination of enamel thinning (revealing darker dentin) and dentin darkening. Responds moderately to whitening.
Sensitivity management and who should not whiten
Tooth sensitivity is the most common whitening side effect — affecting approximately 38% of patients undergoing professional whitening. Management — use potassium nitrate desensitizing toothpaste (Sensodyne) for 2 weeks before whitening; ask your dentist about lower-concentration peroxide protocols; take breaks between whitening sessions. Whitening is not recommended for pregnant women, children under 16, people with active cavities or gum disease (treat first), or people with significant intrinsic staining who have unrealistic expectations about results.
Frequently Asked Questions
How long does teeth whitening last?
Professional whitening results last 1-3 years depending on diet (coffee, tea, wine), smoking, and oral hygiene. Touch-up whitening with dentist-dispensed take-home trays every 6-12 months maintains results. OTC whitening strips used periodically also help maintain professionally whitened results.
Is teeth whitening safe?
Yes — when used as directed. Hydrogen peroxide whitening has been extensively studied and is considered safe for tooth enamel and soft tissue at concentrations used in professional and OTC products. Overuse or prolonged contact with gums causes transient irritation. The enamel damage concerns popularized in some media are not supported by the body of dental research at recommended concentrations.
Why are my teeth sensitive after whitening?
Peroxide penetrates enamel and temporarily increases the permeability of dentinal tubules — the microscopic channels connecting the enamel surface to the nerve. This causes temporary sensitivity to cold, heat, and touch. Sensitivity typically resolves within 24-48 hours of stopping treatment. Pre-treating with potassium nitrate (Sensodyne) and using lower peroxide concentrations reduces this effect.
Can veneers or crowns be whitened?
No. Porcelain, ceramic, and composite restorations do not respond to peroxide whitening — only natural tooth enamel whitens. If your restorations are matched to your current tooth color and you whiten your teeth, the restorations will appear darker than your surrounding teeth. Whiten your teeth first, then match any new restorations to your target shade.
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