Teeth whitening: at the dentist or at home, is it safe and what affects the price

How does teeth whitening work?

Teeth whitening is the chemical lightening of natural teeth with a gel containing hydrogen peroxide or carbamide peroxide (urea peroxide), which releases hydrogen peroxide on contact with the tooth. It changes the colour of the tooth itself, not just the deposits on its surface, and that is what sets it apart from air polishing and from whitening toothpaste.

A 2018 Cochrane review of 71 studies confirmed that peroxide gels dispensed by a dentist lightened teeth compared with placebo, over follow-up periods of 2 weeks to 6 months. The certainty of this evidence was rated low to very low, and no product, concentration or method could be identified as more effective than the others.

The result also depends on the starting point. In an analysis of data from 11 clinical trials, younger people and those with a darker initial shade achieved greater lightening, and each additional year of age reduced the effect by 0.07 units on the shade scale. That is why it is hard to promise a specific shade before treatment.

Lamp, tray or over-the-counter whitening: the methods compared

In-surgery teeth whitening is done at the clinic in one or more sessions, while tray whitening is done at home, in trays fitted to the patient’s teeth, after the first application of the gel at the surgery. Both methods use products at concentrations that EU law allows only under a dentist’s supervision.

A 2025 review (32 studies) found no difference in the risk of sensitivity between the methods, but sensitivity was milder with home whitening. Lightening assessed on a shade guide was the same, and slightly greater with home whitening when measured with a spectrophotometer; the authors rated the quality of the evidence as low.

The American Dental Association (ADA) describes the lamp as a means of speeding up and enhancing the action of the gel in the surgery, although research on its additional benefit is inconclusive. The table sets out the methods patients come across most often.

Is teeth whitening safe? What EU law says

Teeth whitening is permitted in the EU under strictly defined conditions introduced by Council Directive 2011/84/EU, applicable since 31 October 2012. The same rules now appear in Annex III to Regulation (EC) No 1223/2009 on cosmetic products, which applies directly in Poland.

According to EU experts, products containing 0.1% to 6% hydrogen peroxide can be safe only if a clinical examination rules out risk factors and the product is used at the recommended frequency and for the recommended time. Hence the requirement for a dentist to be involved. The ADA also recommends an examination before whitening and, where needed, X-rays.

• Up to 0.1% hydrogen peroxide, present in or released from the product: permitted in any oral care product, including those sold in chemists.
• Over 0.1% and up to 6%: sold only to dentists, and in each treatment cycle the first use is carried out by a dentist or under their direct supervision; the patient may complete the rest of the cycle at home.
• In the same concentration range, use in people under 18 is prohibited, and the packaging must carry a warning about the hydrogen peroxide content and about avoiding contact with the eyes.
• The limit applies to hydrogen peroxide, so for a carbamide peroxide gel what counts is the amount of hydrogen peroxide the product releases.
• The rules make no provision for tooth whitening products stronger than 6% hydrogen peroxide.

Sensitivity after whitening: how common is it and how long does it last?

Tooth sensitivity is the most common side effect of whitening: according to the ADA, mild or moderate sensitivity affects up to two thirds of people at the start of treatment. With trays or strips it may appear within 2 to 3 days of starting and usually resolves by the fourth day after finishing.

In a pooled analysis of data from studies by one research group, the risk of sensitivity was 51% with home whitening and 62.9% in the surgery. The Cochrane review indicates that sensitivity and gum irritation occur more often with higher peroxide concentrations.

Products that reduce sensitivity help little: potassium nitrate applied before whitening lowered the risk by about 12%, which the authors of a 2021 review called a subtle benefit of questionable clinical relevance. The NHS also lists sore gums or a sore throat and white patches on the gums. If the symptoms do not go away after treatment ends, contact your dentist.

Does whitening work on fillings, crowns and veneers?

No: teeth whitening lightens only natural teeth, and crowns, veneers, fillings, dentures and crowns on implants keep their existing colour. The UK’s NHS and the American ADA both say so.

In practice, a visible filling in a front tooth may stand out against the lighter tooth after treatment, and it sometimes needs replacing with material in the new shade. The ADA points out that whitening can temporarily weaken the bond of composite and ceramic materials to enamel, which matters when planning new restorations.

A single tooth that has darkened after an injury or after the pulp has died is a separate matter. A dead tooth is whitened from the inside, using a different procedure from whitening the whole arch, and this is described in a separate article on dead teeth.

Who should not have their teeth whitened?

Whitening with products stronger than 0.1% hydrogen peroxide is not used in people under 18, because EU law prohibits it. The other limitations stem from the condition of the mouth and from precautionary advice, which is why treatment is preceded by an examination.

• People under 18: prohibited by Directive 2011/84/EU for products above 0.1% hydrogen peroxide.
• Unhealthy teeth or gums: the NHS does not recommend whitening in this case, so whatever needs treatment is treated first.
• Pregnancy and breastfeeding: the NHS does not recommend whitening during this time; this is professional caution, not a ban under EU law.
• Teeth that are already sensitive: worth mentioning before treatment, as sensitivity is the most common side effect of whitening.
• Numerous visible fillings, crowns or veneers on the front teeth: they will not change colour, so the result may be uneven.

How long do teeth whitening results last?

The effect of teeth whitening usually lasts several years and needs refreshing over time; the NHS states that it can last around 3 years if the patient follows the dentist’s advice. There is no single figure, because durability depends on habits and on what stained the teeth in the first place.

Long-term follow-up data are scarce. In a small group of 30 people, about 10 years after tray whitening with 10% carbamide peroxide, 43% considered the colour of their teeth to be stable. Stains from tea, coffee, red wine, cola and tobacco build up on the enamel again, so cutting down on them and having surface deposits removed regularly helps the effect last longer.

How much does teeth whitening at the dentist cost, and does the NFZ cover it?

Teeth whitening is not on the list of guaranteed dental treatment services, so the NFZ (Poland’s National Health Fund) does not fund it, whatever the patient’s age. The private cost depends on the method, the number of in-surgery sessions, whether trays need to be made and the amount of gel needed to complete treatment.

In the clinic’s price list, “Wybielanie lampą I sesja” (lamp whitening, first session) costs 1 200 zł and “Wybielanie lampą II sesja” (lamp whitening, second session) 600 zł. “Wybielanie nakładkowe” (tray whitening) is 1 000 zł, “Szyna wybielająca” (whitening tray) 700 zł and “Preparat do wybielania nakładkowego” (tray whitening gel) 150 zł. If hygiene treatment or other treatment is needed before whitening, these are separate items; the final scope and cost are agreed at the consultation, and prices may change.

How teeth whitening works at DentalBlue

At DentalBlue in Białystok, teeth whitening is part of cosmetic dentistry, and the price list covers both methods: lamp whitening at the surgery and tray whitening. Hygiene treatment, which removes deposits from the tooth surfaces, is carried out at the same clinic as part of preventive care. At a visit without pain, the patient has a panoramic X-ray (pantomogram), an examination, a consultation and a written treatment plan with the prices of each stage, so the choice of method is discussed after the teeth and gums have been assessed. The clinic is open Monday to Friday from 8:00 to 20:00 and on Saturdays from 8:00 to 16:00.