Laser Teeth Whitening: Procedure and Benefits

Laser whitening is one of the most advertised cosmetic treatments. This guide describes the appointment, and separates the benefits from the claims.

Key points

• Laser or light whitening is in-clinic whitening in which a peroxide gel is applied to the teeth and a lamp or laser is directed at them.
• The gel does the whitening, and a meta-analysis of 21 trials found that adding light gave no clear extra benefit.³
• In-clinic whitening can be done in about one visit of one to two hours, with the dentist protecting the gums.¹
• Sensitivity and sore gums are known side effects, and the result is not lasting.¹
• Ask what is added to the whitening, how the gums will be protected and what happens if your teeth become sensitive.

If you have seen "laser whitening" advertised, you may wonder what it involves and whether it is worth choosing. Here is the process, with an honest look at what it does and does not add.

What the appointment involves

The NHS describes in-clinic whitening: the gel is applied in the clinic, with a shield or paste protecting the gums, in about one appointment of 1 to 2 hours.¹ With light or laser whitening, the steps are:

1. Examination. The dentist checks your teeth and gums, and treats decay and gum disease first, because whitening is for healthy teeth and gums.¹ They note the starting shade.
2. Cleaning. The teeth are polished to remove surface plaque and stain.
3. Protecting the mouth. A barrier or shield covers the gums, lips and cheeks, and you wear protective glasses.
4. Applying the gel. A peroxide gel is painted on the teeth.
5. Light or laser. A lamp or laser is directed at the teeth for short periods while the gel is in place.
6. Repeating. The gel is renewed, and the cycle may be repeated several times.
7. Finishing. The gel is removed, the teeth are rinsed and the new shade is recorded. A desensitising product may be applied.

What the light does, and does not do

The gel does the whitening. A meta-analysis of 21 trials found that adding light to in-office bleaching gave no improvement in colour change and did not change sensitivity.² So when a clinic says that laser makes the treatment faster or stronger, the evidence does not support it. This does not mean in-clinic whitening is not effective, only that the light may not be adding to it.

The real benefits of in-clinic whitening

• One appointment. It can be done in about one visit of one to two hours.¹
• Supervision. The dentist protects the gums and manages the process.
• Convenience. No trays to wear at home for weeks.
• A visible change in shade for stained natural teeth.¹

A meta-analysis found that at-home and in-office bleaching gave no difference in sensitivity or in whitening effect,³ so the main advantage is time, not a better result.

Strength of the gel

A review of 14 studies with 649 patients found that 35 percent hydrogen peroxide caused more sensitivity than 6 to 20 percent gels, and that the lower strengths changed the colour more on instrumental measures, though patients did not see a clear difference in shade.⁴ Ask what strength is used and why.

Side effects

Sensitivity to cold or sweet food and drink is a known side effect, and so are sore gums or throat and white patches on the gums.¹ These tend to settle in a short time.¹ Heat from a lamp is another thing to ask about, and the dentist should monitor your comfort throughout.

Who should not have it

The NHS lists people aged 17 or younger, people with unhealthy teeth or gums, people who are pregnant or breastfeeding, and people with crowns, dentures or implants, for whom it does not change the colour.¹ Whitening does not change fillings, crowns or veneers, and bleaching can affect restorative materials in laboratory studies.⁵

How long the result lasts

The result is not lasting, and with your dentist's advice it may last around three years.¹ Cutting down on foods and drinks that stain helps the shade last.¹ See how long whitening lasts.

After the appointment

• Avoid staining food and drink, such as tea, coffee, red wine and dark sauces, for the first couple of days.
• Do not smoke.
• Use a desensitising toothpaste if your teeth are sensitive.
• Brush gently and keep your mouth clean.
• Keep your regular check-ups.

Questions to ask before you book

1. What exactly is added to the whitening, light or laser, and what is the gel strength?
2. Is there evidence that the light improves results?
3. How will my gums be protected?
4. What will happen if my teeth become sensitive?
5. Can I see before-and-after results for patients with teeth like mine, with their consent?
6. What will my visible fillings or crowns look like afterwards?

Learn more

Our page on teeth whitening and our guides to conventional and laser whitening and types of whitening give more detail. If your teeth are yellow, see yellow teeth, and for sensitivity see sensitive teeth.

Laser, in-clinic and take-home whitening at a glance

	In clinic with light or laser	In clinic without light	Take-home trays from the dentist
Where	At the clinic	At the clinic	At home
Time	About one to two hours in one visit1	About one to two hours	Daily use for a period set by the dentist
Gel	Stronger peroxide gel	Stronger peroxide gel	Lower-strength gel
Role of the light	Claimed to speed the gel	None	None
Supervision	Dentist protects the gums	Dentist protects the gums	Dentist checks the trays and advises
Sensitivity	Possible	Possible	Possible, often milder

A meta-analysis found no difference in sensitivity or whitening effect between at-home and in-office bleaching, so the choice often comes down to convenience and what suits your teeth.² Your dentist can say which route they advise and why.

Managing sensitivity after the visit

Sensitivity is common in the first day or two. A few steps help.

• Use a desensitising toothpaste, as advised, and spread it on sensitive areas before bed.
• Avoid very cold and very hot food and drink for a couple of days.
• Use a straw for cold drinks so they bypass the teeth.
• Take a painkiller as the label directs if the discomfort is bothering you.
• Stop any further whitening until the teeth feel normal.

If the sensitivity is sharp, lasts more than a few days or comes with gum pain, call your dentist.

A realistic idea of the result

Results differ with the starting colour and the cause of the stain. Teeth with yellow or brown tones from age or food often respond well, while grey tones or stains from inside the tooth may respond less. Fillings, crowns and veneers do not whiten, so they may look darker beside the lightened teeth. Ask your dentist what shade change is realistic for your teeth, and whether any visible restorations will need to be matched. Be cautious of promises of a specific number of shades.

What to wear and bring to the appointment

You do not need much preparation, but a few steps help. Brush and clean between your teeth before you arrive, tell the dentist about any sensitivity or medicines, and mention any dental work you have had recently. Avoid heavily coloured food and drink on the day, since you want the teeth as clean as possible. Bring sunglasses only if the clinic asks, because protective glasses are usually provided. Allow a relaxed schedule, since the appointment takes an hour or two, and plan soft, light-coloured food for the first couple of days afterwards.

Myths and facts

Myth: laser whitening is a different, stronger treatment. It is the same peroxide gel, with a light added, which did not improve colour change in trials.²

Myth: it works on any discolouration. It lightens natural teeth with surface or internal stains, but not crowns, fillings or veneers.¹

Fact: your dentist's examination matters more than the lamp.

How to judge a clinic's claims

Be careful of claims like "whiten by ten shades in an hour" or "no sensitivity". Results vary with the starting colour of your teeth, and sensitivity is a known side effect.¹ A good clinic explains what to expect, shows your starting shade, records the change and does not promise a particular result. Look for honesty about what light or laser can and cannot add.²

Frequently asked questions

How many shades lighter will my teeth go?

It varies, and your dentist can give a realistic range after examining your teeth.

Is it painful?

It should not be, but sensitivity is a known side effect. Tell your dentist if you feel discomfort.¹

Can I eat straight afterwards?

Usually yes, but avoid staining food and drink for a couple of days.

Is laser whitening better than home trays?

At-home and in-office bleaching gave similar results in a meta-analysis,³ so choose on convenience and your dentist's advice.

Can I have whitening if I wear braces?

Usually it is left until the braces are off, because brackets block the gel and leave marks.

Is the lamp heat a concern?

Heat should be minimal, and the dentist should monitor your comfort throughout.

Is laser whitening more effective than other kinds?

The research found that adding light to in-office bleaching gave no clear extra benefit, because the gel does the whitening.³

How soon can I eat normally after whitening?

Your dentist will advise. Many suggest avoiding strongly coloured food and drink, such as tea, coffee, red wine and dark sauces, for the first couple of days.

Does whitening hurt during the procedure?

Most people feel little, though some notice sensitivity or a zing in the teeth as the gel works. Tell the dentist, who can pause, adjust the gel or give you a break.

About the author

Sources

1. NHS website. Teeth whitening (patient information). Page review date 19 August 2025. https://www.nhs.uk/conditions/teeth-whitening/
2. Maran BM, Burey A, de Paris Matos T, Loguercio AD, Reis A. In-office dental bleaching with light vs. without light: a systematic review and meta-analysis. Journal of Dentistry, 2018;70:1-13. https://pubmed.ncbi.nlm.nih.gov/29289725/
3. de Geus JL, Wambier LM, Kossatz S, Loguercio AD, Reis A. At-home vs in-office bleaching: a systematic review and meta-analysis. Operative Dentistry, 2016;41(4):341-356. https://pubmed.ncbi.nlm.nih.gov/27045285/
4. Pontes M, Gomes J, Lemos C, Leao RS, Moraes S, Vasconcelos B. Effect of bleaching gel concentration on tooth color and sensitivity: a systematic review and meta-analysis. Operative Dentistry, 2020;45(3):265-275. https://pubmed.ncbi.nlm.nih.gov/32396502/
5. Attin T, Hannig C, Wiegand A, Attin R. Effect of bleaching on restorative materials and restorations: a systematic review. Dental Materials, 2004;20(9):852-861. https://pubmed.ncbi.nlm.nih.gov/15451241/

Medically reviewed by Dr Anupam Sinha, BDS, MDS – Orthodontics, on 23 October 2026. General information for patients from Orion Dental Clinic, last updated 23 October 2026. It is not advice for one person, so ask a dentist what suits you. To report an error, contact us.