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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.
This guide explains how cool light whitening works, what the light really does, what results to expect, and how it compares with whitening toothpaste, strips, trays and laser whitening.
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 much cooler: in a laboratory study comparing light sources during bleaching, a halogen lamp raised the temperature inside the tooth more than an LED unit 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. A professional 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).
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 light is used to support and speed up that reaction during the session.
What a session looks like at The Smile Bar
- Briefing and assessment. We explain the treatment, examine 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.
What does the light actually do?
The honest answer: researchers still disagree on how much the light adds. Here is what the main reviews of clinical studies found:
- A 2012 meta-analysis of 11 clinical studies found that light might not improve results with strong gels (25 to 35% hydrogen peroxide) and increased the risk of sensitivity. With lower-concentration gels, light could improve the immediate result, but the authors said more research was needed.
- A 2018 meta-analysis found that, overall, light changed neither the whitening effect nor the risk of sensitivity. The authors warned that the protocols they compared varied a lot.
- A 2026 review of 24 systematic reviews concluded that light (LED, halogen or laser) generally did not improve the efficacy of in-office bleaching and may increase sensitivity.
Most of this research looked at the strong gels used in dental clinics. For low-concentration gels, the evidence is thinner.
What this means for you: an LED light on its own doesn’t whiten teeth. The gel does the work, and the light is a supporting part of the treatment. 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. How far you go depends mainly on your stains.
- 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. These stains can lighten, but often need longer treatment than a single visit. 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. Coffee, tea, red wine and smoking bring stains back faster, while a good daily routine helps you keep your new shade longer. You can see examples on our results page.
Is cool light whitening safe? Sensitivity and side effects
Professional whitening is considered safe for healthy adult teeth when it’s done with suitable products and a check of your teeth beforehand. Like any peroxide-based whitening, it can have side effects:
- Temporary tooth sensitivity. This is the most common side effect of whitening. It’s usually mild to moderate and fades within a few days.
- Gum irritation. It can happen if the gel touches the gums, and it is usually short-lived.
Here is how our treatment is designed to limit sensitivity:
- your teeth are examined before any whitening;
- the gel is low-concentration, pH-neutral and water-based;
- the LED lamp emits no UV and stays cool;
- 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. For more detail, read our guide: Is teeth whitening safe?
Who should not have cool light whitening
Whitening is not recommended 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.
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:
- Single Whitening: 1 × 20 min, about 30 minutes in total;
- Double Whitening: 2 × 20 min, about 60 minutes in total;
- Triple Whitening: 3 × 20 min, about 90 minutes in total.
Total times include the briefing, the cleaning step and the breaks.
Cool light vs traditional whitening methods
Traditional methods whiten gradually at home. Cool light whitening gives a visible change in one visit. Here is how they compare:
| Method | How it whitens | Time to see a result | Main limits |
|---|---|---|---|
| Whitening toothpaste | Mild abrasives polish away surface stains. Some add a low level of peroxide. | Gradual, with daily use | Removes surface stains but doesn’t significantly change the natural colour of teeth |
| Whitening strips | Thin strips coated with a peroxide gel, worn at home | Repeated applications over several days or more | Results can be uneven; gel on the gums can irritate them |
| Trays with bleaching gel | Trays filled with gel, worn at home, often overnight | Regular use over a longer period | Needs consistency; results build slowly |
| Cool light (LED) whitening | Professional 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 activated by a laser instead of LEDs | One visit | Not offered at The Smile Bar |
Choosing a toothpaste? Our guide to the best whitening toothpaste can help. For trays and at-home gels, see teeth whitening gel: facts and myths.
Cool light vs Zoom whitening
Zoom is a brand, not a different kind of light. Philips Zoom WhiteSpeed, used in dental clinics, also relies on a blue LED lamp, combined with a 25% hydrogen peroxide gel. The Smile Bar doesn’t use Zoom or laser. For a detailed side-by-side, read our comparison of laser, LED and Zoom teeth whitening.
Which method is right for you?
- Light surface stains and a small budget: start with a whitening toothpaste.
- Happy to whiten slowly at home: strips or trays can work if you use them consistently.
- You want a visible change in one visit, before an event or during a trip: professional cool light whitening.
- Already whitened: a whitening toothpaste and mouthwash routine helps you keep the result.
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:
- Single Whitening: 2,399 THB
- Double Whitening: 4,399 THB
- Triple Whitening: 5,799 THB (best seller)
You can book any package and upgrade on the day. Full details and add-ons are on our teeth whitening prices page. Visiting from abroad? Our guide to teeth whitening in Thailand explains how to fit a session into your trip.
After your session: the 72-hour rule
For 72 hours after whitening, teeth pick up new stains more easily. Without protection, avoid:
- coffee, tea, red wine and dark sodas;
- chocolate, red meat, soy sauce and chilli sauce;
- acidic food and drinks such as tomatoes, citrus and vinegar;
- smoking.
Don’t want to wait three days? Nano Protection (750 THB) is a sealing varnish with a triple fluoride formula, applied right after your session. It protects your result, helps remineralise your teeth and lets you eat and drink normally straight away.
Over the following weeks, use the whitening toothpaste and mouthwash from your package. Both are non-abrasive and peroxide-free. Rinse with 10 ml of mouthwash first, then brush. Refills are available in our online shop.
Frequently asked questions
Does cool light teeth whitening work?
Yes. The whitening comes from the hydrogen peroxide gel, and the LED light supports the process during the session. 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.
Does the light whiten teeth on its own?
No. An LED light alone doesn’t whiten teeth: the peroxide gel does. Studies disagree on how much the light adds, and several reviews found little or no extra effect with strong gels. That’s why the gel, the session time and your type of stains matter most.
Is cool light whitening the same as LED, UV or laser whitening?
Cool light, cold light and LED whitening are different names for the same thing: a whitening gel used with an LED lamp. It doesn’t use UV light, and it isn’t laser whitening, which uses a laser beam instead of LEDs.
Is cool light teeth whitening safe? What are the side effects?
It is considered safe for healthy adult teeth when done with suitable products after a check of your teeth. The most common side effects are temporary tooth sensitivity and gum irritation, which usually fade within a few days. It’s not recommended if you are pregnant or breastfeeding, wear braces, or are under 18.
What’s the difference between cool light and Zoom whitening?
Zoom is a brand-name in-office system by Philips. It also uses a blue LED lamp, combined with a 25% hydrogen peroxide gel. Cool light whitening at The Smile Bar uses a low-concentration, pH-neutral gel from Sweden with a UV-free LED lamp. 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. Every package includes a whitening toothpaste and mouthwash to take home.
Ready to try it? Book your cool light whitening session at our studio in Siam Square, next to BTS Siam, open every day from 10 am to 8 pm.
