Teeth whitening: every option compared
Whitening toothpaste, strips, LED kits, dentist trays and in-office bleaching compared: peroxide strength, results, time, US cost and who should skip it.
Written by the Glowpedia team ยท not yet reviewed by our dentist
On this page
Quick answer Peroxide is what actually lightens teeth: strips and dentist-made trays work in 1โ4 weeks and in-office bleaching in one visit, while whitening toothpaste only lifts surface stains. Crowns, veneers and fillings don't change color, and whitening isn't advised in pregnancy, under 16 or with untreated gum disease.
How whitening works
Teeth darken in two ways. Surface stains from coffee, tea, red wine and tobacco sit on the enamel. Deeper discoloration comes from inside the tooth, for example when enamel thins with age and the yellower dentin underneath shows through. Polishing and mild abrasives can only lift surface stains. To change the color of the tooth itself you need a bleach, and in dental products that means a peroxide.
Two peroxides are used:
- Hydrogen peroxide works fast, so it's used in strips and in the dentist's chair. It's also more likely to cause sensitivity.
- Carbamide peroxide slowly breaks down into hydrogen peroxide and urea, so it suits trays worn for a few hours or overnight. As a rough rule it's about one third as strong: 10% carbamide peroxide โ 3.5% hydrogen peroxide, and 35% carbamide โ 12% hydrogen.
A higher percentage works faster but raises the risk of sensitive teeth and sore gums. It doesn't make the final shade much whiter; it just gets there sooner.
Every option side by side
Prices are typical US ranges and vary by city and product.
| Option | Active ingredient | Time to results | Typical US cost | Best for |
|---|---|---|---|---|
| Whitening toothpaste | Mild abrasives, sometimes a little peroxide | 2โ6 weeks, subtle | $4โ15 a tube | Keeping surface stains away |
| Whitening strips | Hydrogen peroxide, often 6โ14% | 1โ2 weeks | $25โ60 a box | Mild yellowing on a budget |
| LED home kits | Peroxide gel plus a light | 1โ3 weeks | $30โ150 | Similar to strips |
| Dentist take-home trays | Carbamide peroxide, often 10โ22% | 1โ4 weeks | $250โ600 | Even results, adjustable strength |
| In-office bleaching | Hydrogen peroxide, 15โ43% | One visit of 1โ2 hours | $300โ1,000+ | Fast results before an event |
What results to expect
- Yellow teeth usually respond well. Brown teeth respond less, and gray teeth (for example from an old injury or some medicines) may barely change.
- In-office bleaching can lighten teeth by several shades in one visit. Dentists often add take-home trays to finish or maintain the result.
- About LED lights: studies of in-office lights found that with stronger gels the light added little extra whitening but raised the chance of sensitivity. Home LED kits use much weaker light, so most of the effect comes from the gel.
- Results fade. With good habits they can last from about 1 year up to around 3 years. Coffee, tea, red wine and smoking shorten that, and a few touch-up days every 6โ12 months help. See coffee, tea and wine stains.
Who should not whiten (or should wait)
- Crowns, veneers, fillings and bonding don't whiten. On front teeth, whitening can leave them looking darker than your natural teeth. Your dentist may suggest whitening first, then replacing old fillings to match.
- Pregnancy and breastfeeding: whitening is not recommended. Wait until afterward.
- Under 16: most dentists advise waiting until teeth and gums are mature. In the UK, whitening isn't done for anyone under 18.
- Gum disease, cavities or exposed roots: get these treated first, since peroxide on them can be painful. Read more on gum health.
- Already sensitive teeth: start with a low strength and short sessions; see whitening without the pain.
Whiten safely
- Follow the label time exactly. Leaving strips or gel on longer doesn't whiten more and can irritate gums.
- When you can, choose home products with the ADA Seal of Acceptance, and be wary of whitening offered by non-dentists in salons or kiosks.
- Skip lemon juice, vinegar, harsh baking-soda scrubs and charcoal; acids and gritty powders can wear enamel. More in whitening myths.
- Stop and contact a dentist if you get strong pain, swelling or white patches on your gums.
What you need for this
These open Amazon searches for the kind of product the guide describes; check the ingredients and reviews before you buy. As an Amazon Associate we earn from qualifying purchases.
See a dentist before whitening if you have crowns, veneers or fillings on your front teeth, sensitive teeth, gum problems or a single tooth that has darkened. Stop and book a visit if pain, swelling or white patches on your gums last more than a few days.
Questions people ask
Does whitening damage enamel?
Used as directed, peroxide whitening is considered safe for enamel. Overuse, very high strengths or acidic home remedies can roughen enamel and irritate gums, so stick to the label times and take breaks.
How long does teeth whitening last?
Usually from about 1 to 3 years, depending on what you eat and drink and whether you smoke. Short touch-ups every 6โ12 months help keep the shade.
Can I whiten crowns or veneers?
No. Peroxide only lightens natural tooth structure. Crowns, veneers and fillings keep their original color, so they may need replacing if you want them to match.
Is carbamide peroxide weaker than hydrogen peroxide?
Yes, roughly one third as strong: 10% carbamide peroxide releases about 3.5% hydrogen peroxide. It works more slowly, which is why it's often worn for hours or overnight in trays.