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Teeth whitening gel is a peroxide-based gel that lightens the colour of your teeth. The peroxide passes through the enamel and breaks down the pigments that make teeth look yellow. Dental clinics, whitening studios and home kits all use a version of it.
Quick answer
- What’s in it: hydrogen peroxide or carbamide peroxide, in a gel base.
- How it differs: mainly by strength, and by who is allowed to supply it.
- Is it safe? Used as directed, the main side effects are temporary sensitivity and gum irritation.
- In Thailand: strong gels aren’t sold over the counter. The Smile Bar doesn’t sell gel: we use it in the studio.
What is teeth whitening gel?
| Ingredient | What it does |
|---|---|
| Hydrogen peroxide or carbamide peroxide | The active ingredient: it does the whitening |
| Gel base (water, glycerine, thickener) | Keeps the peroxide on the tooth |
| Desensitising agents (in some gels) | Added to limit sensitivity |
| Flavour | Makes it more pleasant |
How does teeth whitening gel work?
- The gel is applied to the teeth, by a professional or in a tray or strip.
- The peroxide passes through the enamel and reaches the coloured molecules underneath.
- It breaks those molecules down. The tooth looks lighter. The enamel itself isn’t removed.
Some treatments shine a lamp on the gel. Studies of in-clinic whitening have not shown that the light improves the result: the gel does the work.
Whitening gel is supplied in syringes for precise application.
Types of whitening gel
| Type | How it acts | Where you find it |
|---|---|---|
| Hydrogen peroxide | Acts directly and quickly | In-chair treatments, some strips |
| Carbamide peroxide | Breaks down into hydrogen peroxide, more slowly | Take-home trays from a dentist |
| PAP (peroxide-free) | A different whitening agent | Over-the-counter kits and strips |
Gels used by dentists vs gels sold to the public
| Through a dental professional | Sold to the public | |
|---|---|---|
| Strength | Stronger | Much weaker, or peroxide-free |
| How it’s used | In the chair, or in trays made to fit | Strips, pens, one-size trays |
| Speed | Same day in the chair. Weeks with trays | Weeks |
| Check beforehand | Yes | No |
The rules on who can sell what differ by country. Europe and Southeast Asia limit what can be sold directly to the public much more strictly than the United States.
Are teeth whitening gels safe?
| Side effect | How common | What to do |
|---|---|---|
| Tooth sensitivity | Common, usually temporary | Pause, and avoid very cold or hot drinks |
| Gum irritation | Possible where gel touches the gum | Wipe off excess gel |
| Uneven colour | Possible with crowns, veneers or fillings, which don’t whiten | Ask a dentist first |
The American Dental Association lists temporary sensitivity and gum irritation as the most common side effects of whitening. More in does teeth whitening hurt?
For the peroxide itself, see our guide to hydrogen peroxide for teeth whitening.
Teeth whitening gel: myths and facts
| Myth | Fact |
|---|---|
| Whitening gel strips away enamel | The gel passes through the enamel. It doesn’t remove it |
| One application gives a permanent result | Whitening isn’t permanent. See how long teeth whitening lasts |
| Everyone gets sensitive teeth | Sensitivity is common but not universal, and usually temporary |
| Gel works the same on every tooth | Surface stains respond best. Crowns, veneers and fillings don’t whiten |
| Shop-bought gel is the same as a professional’s | Gels sold to the public are much weaker, so they work more slowly |
Can you buy teeth whitening gel in Bangkok?
- In shops and local apps: mostly peroxide-free or very mild products.
- From a dental clinic: take-home tray kits with a stronger gel, at about 3,200 to 7,000 THB.
- From marketplaces: imported gels sold by third-party sellers. Check the product and the seller carefully.
- From The Smile Bar: no. We don’t sell whitening gel or home kits.
The same goes for strips: see whitening strips in Bangkok.
Gel at home vs LED whitening in a studio
| Home gel or kit | LED session at The Smile Bar | |
|---|---|---|
| Time to a result | Two weeks or more | The same day |
| Your time | Daily, for weeks | One visit of 30 to 90 minutes |
| Who applies it | You | Our team |
| Cost in Bangkok | A few hundred THB for shop products. 3,200 to 7,000 THB for a clinic kit | 2,399, 4,399 or 5,799 THB |
Need a result quickly? See how to whiten teeth fast. Comparing with dental clinics? See Zoom whitening in Bangkok.
The gel used at The Smile Bar
The gel is applied in the studio, 20 minutes at a time.
- Brand: Brilliant Smile, made in Sweden.
- Formula: low-concentration hydrogen peroxide, pH-neutral, water-based. It’s designed to limit sensitivity.
- How it’s used: applied in the studio and combined with a UV-free LED lamp, for 20 minutes per session.
- Result: 2 to 9 shades lighter, 5 on average.
- Not for: women who are pregnant or breastfeeding, people who wear braces, anyone under 18.
More on the lamp in cool light (LED) teeth whitening.
Book a whitening session in Siam Square
- Single Whitening: 1 × 20 minutes, 2,399 THB
- Double Whitening: 2 × 20 minutes, 4,399 THB
- Triple Whitening: 3 × 20 minutes, 5,799 THB
Book online or walk in when a chair is free. We’re on the ground floor at 392/27-28 Siam Square Soi 5, next to BTS Siam, open every day from 10 am to 8 pm. All prices are on our teeth whitening prices page.
Frequently asked questions
What is teeth whitening gel made of?
Hydrogen peroxide or carbamide peroxide in a gel base of water, glycerine and a thickener. Some gels add ingredients to limit sensitivity.
Are teeth whitening gels safe?
Used as directed, yes for most healthy adult teeth. The most common side effects are temporary tooth sensitivity and gum irritation.
What is the difference between hydrogen peroxide and carbamide peroxide gel?
Hydrogen peroxide acts directly. Carbamide peroxide breaks down into hydrogen peroxide and works more slowly, which is why it’s common in take-home trays.
What whitening gels do dentists use?
Stronger peroxide gels than those sold in shops, applied in the chair or supplied with trays made to fit your teeth.
How long do you keep teeth whitening gel on for?
It depends on the product: follow its instructions. At The Smile Bar, each session is 20 minutes.
Does whitening gel damage enamel?
The gel passes through the enamel to reach the pigments. It doesn’t strip the enamel away. Overusing whitening products can cause sensitivity.
Can I buy the gel The Smile Bar uses?
No. We don’t sell whitening gel. For upkeep at home we sell whitening toothpaste and mouthwash, which contain no hydrogen peroxide.
Does whitening gel work on crowns or veneers?
No. Only natural teeth whiten.
