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Cool light teeth whitening, also called LED or cold light whitening, is a professional treatment where a hydrogen peroxide gel is applied to your teeth while a blue LED lamp shines on them. It’s the only technology we use for teeth whitening in Bangkok at The Smile Bar: 20-minute sessions under a UV-free LED lamp, with a result you can see before you leave.
One thing to know from the start: the gel does the whitening. The lamp is part of the method, not a magic ingredient.
Cool light whitening at a glance
| What it is | A whitening gel used with an LED lamp |
| Type of light | Visible blue LED light. Not laser |
| UV | None |
| Session time | 20 minutes, one to three sessions in a visit |
| Result at The Smile Bar | 2 to 9 shades lighter, 5 on average |
| Price at The Smile Bar | From 2,399 THB |
| Not for | Pregnant or breastfeeding women, people who wear braces, under 18s |
What is cool light teeth whitening?
“Cool light” describes the lamp, not the gel. Older whitening lamps used halogen bulbs, which give off noticeable heat. LED lamps run cooler: in a laboratory study comparing light sources during bleaching, a halogen lamp raised the temperature inside the tooth more than LED units did. That’s where the names cool light and cold light come from.
Three things set cool light whitening apart:
- LED, not laser. Laser whitening uses a laser beam. Cool light whitening uses LEDs.
- No UV. Whitening LEDs emit visible blue light, not ultraviolet light.
- Done in the chair. The gel and lamp are used during an in-studio or in-clinic session, instead of a kit you use alone at home.
At The Smile Bar, the lamp is a European-made, UV-free LED lamp (you may also see it described as a “plasma” LED lamp).
Cool light, cold light, blue light, LED, plasma: same thing?
| Term | What it means | At The Smile Bar |
|---|---|---|
| Cool light, cold light | An LED whitening lamp, which gives off less heat than halogen | Yes |
| Blue light, LED | The colour and the technology of the same lamp | Yes |
| Plasma | A trade name sometimes used for LED whitening lamps | Yes |
| UV | Ultraviolet lamps, used in some older systems | No |
| Laser | A laser beam instead of LEDs | No |
The cool light lamp at The Smile Bar is a UV-free LED lamp.
How does cool light teeth whitening work?
The whitening itself comes from the gel. Hydrogen peroxide passes through the enamel and breaks down the pigments that make teeth look yellow or stained. The LED lamp is used together with the gel during the session.
What a session looks like at The Smile Bar
- Briefing and shade check. We explain the session, ask about your teeth and record your starting shade on a shade guide.
- Pre-whitening cleaning. You rinse with our whitening mouthwash, then brush with our whitening toothpaste.
- Gel application. Your gums are protected, then a Brilliant Smile whitening gel from Sweden is applied to your teeth. It’s pH-neutral, water-based and made with a low concentration of hydrogen peroxide.
- Light session. You sit under the UV-free LED lamp for 20 minutes. Depending on your package, you do one, two or three sessions.
- Final shade. We check your new shade against the same guide and give you aftercare advice.
Does the light actually whiten teeth? What studies say
Not on its own, and reviews of clinical trials haven’t found that light clearly improves the result. Here is what they concluded.
| Review | What it covered | What it found |
|---|---|---|
| 2012 meta-analysis | 11 clinical studies | With strong gels, light didn’t improve results and raised the risk of sensitivity. With weaker gels it might help the immediate result |
| 2018 meta-analysis | 21 randomised trials | Light changed neither the whitening effect nor the risk of sensitivity |
| 2019 network meta-analysis | 28 studies | No type of light did better than whitening without light |
| 2026 review of reviews | 24 systematic reviews | Light (LED, halogen or laser) generally didn’t improve the result |
Most of this research looked at the strong gels used in dental clinics. For low-concentration gels like ours, the evidence is thinner.
What this means for you: an LED light on its own doesn’t whiten teeth. The gel does the work. Be wary of any product that presents the light as the main reason teeth get whiter, including home LED kits.
Does cool light teeth whitening work? Results and limits
Yes, for most people, as long as expectations match the type of staining. At The Smile Bar, teeth usually get 2 to 9 shades lighter, 5 on average, measured on the same shade guide before and after.
- Respond best: surface stains from coffee, tea, red wine, smoking and food.
- Less predictable: deeper discolouration inside the tooth, for example from fluorosis or certain antibiotics such as tetracycline. White spots tend to respond less than brown stains.
- No change: crowns, veneers, fillings and bonding keep their original colour. Only natural teeth whiten.
How long the result lasts depends on your habits: see how long teeth whitening lasts. You can see examples on our results page.
Before and after a cool light session at The Smile Bar.
Is cool light whitening safe? Heat, UV and sensitivity
| Question | Short answer |
|---|---|
| Does the lamp heat the teeth? | Every whitening lamp warms the tooth a little. In a lab study, LED lamps warmed it least and halogen most |
| Is there UV? | No. The lamp emits visible blue light |
| Will my teeth be sensitive? | Possibly. Temporary sensitivity is the most common side effect of any whitening, according to the American Dental Association |
| Can my gums get irritated? | Yes, if gel touches them. It’s usually short-lived |
How our sessions are designed to limit sensitivity:
- the gel is low-concentration, pH-neutral and water-based;
- the LED lamp emits no UV;
- sessions last 20 minutes, with a break between sessions on Double and Triple packages.
If your teeth are already sensitive, tell the team during the briefing. More in does teeth whitening hurt? and is teeth whitening safe?
Who should not have cool light whitening
We don’t whiten teeth if you:
- are pregnant or breastfeeding;
- wear braces;
- are under 18.
If you have untreated cavities, gum problems or tooth pain, see a dentist before any kind of whitening.
Cool light vs other whitening methods
| Method | How it whitens | Time to see a result | Main limits |
|---|---|---|---|
| Whitening toothpaste | Mild abrasives polish away surface stains | Gradual, with daily use | Doesn’t change the natural colour of teeth |
| Whitening strips | Strips coated with a whitening gel, worn at home | Two weeks or more | Results can be uneven |
| Trays with bleaching gel | Trays filled with gel, worn at home | Several weeks | Needs consistency |
| Cool light (LED) whitening | Gel applied in the chair, under a UV-free LED lamp | One visit, 20-minute sessions | Costs more upfront. Doesn’t whiten crowns, veneers or fillings |
| Laser whitening | Gel used with a laser instead of LEDs | One visit | Not offered at The Smile Bar |
Choosing a toothpaste? See our guide to the best whitening toothpaste. For trays and at-home gels, see teeth whitening gel explained.
Cool light vs Zoom whitening
Zoom is a brand, not a different kind of light. Philips Zoom, used in dental clinics, also relies on a blue LED lamp, with a stronger gel applied by a dentist. The Smile Bar doesn’t use Zoom. For Bangkok prices and a full comparison, see Zoom teeth whitening in Thailand.
Cool light vs laser whitening
Laser whitening uses a laser beam instead of LEDs. No type of light has been shown to work better than another. We don’t offer laser: our guide to laser teeth whitening in Bangkok compares the two.
How long does a cool light whitening session take?
Each session under the light lasts 20 minutes. Everything happens in one visit, with no follow-up appointment.
How much does cool light teeth whitening cost in Bangkok?
At The Smile Bar, prices are fixed and every package includes a whitening toothpaste and mouthwash to take home.
| Package | Under the lamp | Visit | Price |
|---|---|---|---|
| Single Whitening | 1 × 20 minutes | About 30 minutes | 2,399 THB |
| Double Whitening | 2 × 20 minutes | About 60 minutes | 4,399 THB |
| Triple Whitening | 3 × 20 minutes | About 90 minutes | 5,799 THB |
- Nano Protection: 750 THB
- Cleaning and Scaling: 950 THB, performed by our dentist, only together with a whitening session
You can book any package and upgrade on the day. Details are on our teeth whitening prices page. Visiting from abroad? See our guide to teeth whitening in Thailand.
After your session: the 72-hour rule
For 72 hours after whitening, we ask you to avoid:
- coffee, tea, red wine and dark sodas;
- chocolate, soy sauce and chilli sauce;
- acidic food and drinks such as tomatoes, citrus and vinegar;
- smoking.
The full list is in what to eat after teeth whitening. With the Nano Protection add-on (750 THB), we lift the 72-hour rule.
Book cool light whitening at The Smile Bar, Siam Square
The Smile Bar studio in Siam Square, Bangkok.
- Where: ground floor, 392/27-28 Siam Square Soi 5, next to BTS Siam
- When: every day, 10 am to 8 pm
- How: book your cool light whitening session, or walk in when a chair is free
Frequently asked questions
Does cool light teeth whitening work?
Yes. The whitening comes from the gel, used together with the LED lamp. At The Smile Bar, teeth usually get 2 to 9 shades lighter, 5 on average. Surface stains from coffee, tea, wine or smoking respond best.
Is cold light teeth whitening the same as cool light?
Yes. Cool light, cold light and LED whitening are different names for the same thing: a whitening gel used with an LED lamp.
Does the light whiten teeth on its own?
No. An LED light alone doesn’t whiten teeth: the gel does. Reviews of clinical trials found little or no extra effect from the light.
Is cool light whitening the same as LED, UV or laser whitening?
It’s LED whitening. It doesn’t use UV light, and it isn’t laser whitening, which uses a laser beam instead of LEDs.
Does the lamp get hot?
LED lamps give off less heat than the halogen lamps used in the past. You may feel slight warmth.
Is cool light teeth whitening safe? What are the side effects?
The most common side effects are temporary tooth sensitivity and gum irritation, which usually fade within a few days. We don’t whiten teeth for women who are pregnant or breastfeeding, people who wear braces, or anyone under 18.
Do home LED whitening kits work the same way?
They also rely on a gel. The small light in a home kit hasn’t been shown to add to the result.
What’s the difference between cool light and Zoom whitening?
Zoom is a brand-name system used by dentists. It also uses a blue LED lamp, with a stronger gel. Cool light whitening at The Smile Bar uses a low-concentration, pH-neutral gel from Sweden. We don’t offer Zoom.
How much does cool light teeth whitening cost in Bangkok?
At The Smile Bar, Single Whitening costs 2,399 THB, Double Whitening 4,399 THB and Triple Whitening 5,799 THB.
