Many clinics advertise laser or light whitening as a faster, stronger option. This guide compares it with conventional whitening, and looks at what the trials found.
Key points
- Whitening uses a peroxide gel, which is a bleach that works on the natural tooth, and it only lightens natural teeth.1
- At-home and in-office bleaching gave no difference in sensitivity or whitening effect in a meta-analysis of randomised trials.2
- Adding light or a laser does not appear to give a better colour change, because the gel does the work.3
- Stronger gel is not clearly better and can cause more sensitivity.
- Products from a pharmacy, online or a salon do not work as well and may harm your teeth and gums.1
The word "laser" sounds modern and powerful, and it is widely used in whitening advertising. Before choosing, it helps to know what actually does the whitening and whether the light adds anything.
What whitening does
Whitening uses a peroxide gel, which is a bleach that works on the natural tooth.1 It only lightens natural teeth: crowns, dentures and implants stay the same colour.1 It can help with staining from age, frequent coffee, tea or red wine, or smoking.1 Strong whitening gels should only be used or sold by dental professionals who know how to use them correctly.1
Conventional whitening
Conventional whitening has two forms.
- At home: whitening gel and trays made to fit your teeth are worn at home, usually for around 2 to 6 weeks.1
- In the clinic: 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
In a meta-analysis of randomised trials, at-home and in-office bleaching gave no difference in sensitivity or in whitening effect, so the choice is mostly about time and convenience.2
Light and laser whitening
Some clinics add a special light or a laser to the in-office gel, with the idea that light speeds up the bleaching. 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.3 In other words, the peroxide does the work, and the light does not appear to add to it in the trials. The NHS notes that light or laser is sometimes added, but the review found it did not improve the result.3
What does matter: the 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 So a stronger gel is not clearly better, and it can make teeth more sensitive.
Comparing the options
| Home trays | In-clinic gel | In-clinic gel with light or laser | |
|---|---|---|---|
| Time | 2 to 6 weeks1 | One visit of 1 to 2 hours1 | One visit |
| Effect | Similar to in-clinic2 | Similar to home2 | No better colour change3 |
| Sensitivity | Similar2 | Similar2 | No change3 |
| Supervision | Dentist-supplied trays | In clinic | In clinic |
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 If you have sensitive teeth already, ask your dentist before whitening. See our guide to sensitive teeth and our page on sensitive teeth.
Fillings, crowns and veneers
Whitening does not change fillings, crowns or veneers, and in laboratory studies, bleaching can affect restorative materials, although no clinical report was found of a restoration that had to be renewed because of it.5 Ask your dentist what to expect if you have visible restorations, because they may stand out against lighter teeth.
Products from pharmacies, salons and online
The NHS says products from a pharmacy, online or a salon do not work as well and may harm your teeth and gums, and that strong whitening chemicals should only be used or sold by dental professionals.1 Be cautious about kits that claim dramatic results.
Who should not have whitening
The NHS lists several groups who should not have it: 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 Your dentist will examine you first, and treat decay and gum disease before whitening.
How long it 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, although the colour will fade over time.1 Our guide to how long whitening lasts goes into more detail.
How to choose
- Have an examination first.
- Ask what gel strength is used and why.
- Be wary of claims that light or laser makes the result better or faster, because the trials do not show it.3
- Consider home trays if you do not mind the time, and in-clinic if you want one visit.
- Think about sensitivity.
For an overview of the methods, read types of teeth whitening, and our page on teeth whitening. For the procedure with light, see laser teeth whitening.
Reading a whitening advert carefully
Adverts for whitening can be persuasive. A few questions help you read between the lines.
- "Laser" or "light-activated": the light is an add-on, and the gel is what whitens.3
- "Up to X shades in one hour": results depend on your starting colour and the cause of the stain.
- "No sensitivity": sensitivity is a known side effect of whitening, so a claim that it never happens deserves a question.1
- "Suitable for everyone": the NHS lists groups who should not have whitening.1
- "Lasts for life": the result is not lasting.1
- Before-and-after photographs: ask whether they were taken in the same light and with consent.
If a clinic cannot explain the gel strength, the protection for your gums and what happens if your teeth become sensitive, ask someone who can.
Home or clinic: a decision guide
| If you… | You might prefer |
|---|---|
| Want it done in one visit | In-clinic gel, with or without light |
| Do not mind wearing trays for a few weeks | Home trays supplied by the dentist |
| Have sensitive teeth | Home trays with a lower-strength gel, spread over more days |
| Want to control the pace | Home trays |
| Prefer the dentist to apply and monitor | In clinic |
| Have an event soon | Plan a few weeks ahead, since sensitivity may need time to settle |
Either route should begin with an examination and finish with a review. The studies found similar results from both, so the choice is mostly about convenience and comfort.2
Day to day: what each feels like
With home trays, you wear soft trays with gel for a set time each day, often for a couple of weeks or more.1 You are in control, and you can pause if your teeth become sensitive. With in-clinic whitening, you sit for an hour or two while the gel is applied, and your gums are protected by a barrier. Some people notice a zing in the teeth during or after the session, which is why a desensitising product may be offered.
Whichever you choose, avoid strongly coloured food and drink for the first couple of days, and keep up your cleaning.
Questions to ask a clinic before you book
- What gel strength will you use, and why?
- Do you add light or a laser, and what is the evidence that it helps?
- How will you protect my gums and lips?
- What will you do if my teeth become sensitive?
- How many visits or days will it take?
- What will my fillings, crowns or veneers look like afterwards?
- Will I have an examination first, and a review after?
A clinic that answers these plainly, and that does not promise a number of shades, is describing the treatment fairly.1
Myths and facts
Myth: laser whitening is stronger. The strength is in the gel, and light did not improve colour change in trials.3
Myth: whitening damages enamel. The NHS lists sensitivity and sore gums as known side effects, which usually settle,1 and your dentist can advise on risks for your teeth.
Fact: expectations matter. Whitening lightens the natural colour, and it does not make teeth white beyond what your teeth can achieve. The research on cosmetic dentistry raises concerns about expectations.6
Frequently asked questions
Is laser whitening more effective?
A meta-analysis of 21 trials found that adding light gave no better colour change.3
Is in-clinic whitening better than home whitening?
A meta-analysis found no difference in sensitivity or whitening effect.2
Can I whiten over crowns?
No. Crowns, dentures and implants stay the same colour.1
Is whitening suitable for teenagers?
The NHS lists people aged 17 or younger among those who should not have it.1
Is a stronger gel better?
Not clearly. A review found a high-strength gel caused more sensitivity than a lower strength without a clear extra benefit, so gel strength should be chosen with your dentist.
Can I whiten at home with products from the pharmacy?
The NHS says products from a pharmacy, online or a salon do not work as well and may harm your teeth and gums, so it advises seeing a dentist.1
Is whitening suitable during pregnancy or breastfeeding?
The NHS lists people who are pregnant or breastfeeding among those who should not have whitening, so wait and ask your dentist.1
About the author
Dr Anupam Sinha, BDS, MDS – Orthodontics. BDS (2002), KLE Vishwanath Katti Institute of Dental Sciences, Belgaum. MDS in Orthodontics (2006), SDM College of Dental Sciences, Dharwad. His thesis work won a national research award in 2005, and he holds a certification in aesthetic dentistry. He sees patients at Orion Dental Clinic in Greater Kailash 1, South Delhi. Read the full profile of Dr Anupam Sinha.
Sources
- NHS website. Teeth whitening (patient information). Page review date 19 August 2025. https://www.nhs.uk/conditions/teeth-whitening/
- 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/
- 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/
- 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/
- 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/
- Doughty J, Lala R, Marshman Z. The dental public health implications of cosmetic dentistry: a scoping review of the literature. Community Dental Health, 2016;33(3):218-224. https://pubmed.ncbi.nlm.nih.gov/28509518/
Medically reviewed by Dr Anupam Sinha, BDS, MDS – Orthodontics, on . 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.