Teeth whitening: in the clinic, with a laser or at home? How to choose

21 September 2026 · Dr. Sergiu Calancea · 4 min read

Smiling patient looking at her white teeth in a hand mirror while sitting in the dental chair

The differences between in-clinic, laser and at-home whitening, what results you can expect, how long they last, who shouldn't whiten their teeth and what it costs.

Why teeth get darker

Tooth enamel is not a perfectly smooth surface: it has microscopic pores. Pigments from coffee, black tea, red wine, coloured soft drinks and cigarette smoke seep into these pores year after year. At the same time, as we age, the dentine under the enamel turns more yellow, while the enamel gets thinner and lets more of it show through. The result: your teeth look darker and darker, even if you brush properly.

“Whitening” toothpaste and brushing only remove surface stains. Professional whitening uses a gel that releases active oxygen, which penetrates the enamel and breaks down the pigments from within. That is why the difference is visible and lasts a long time.

What needs to happen before whitening

Whitening is only done on healthy teeth and gums. Before the session we do a professional cleaning, because tartar and surface stains stop the gel from working evenly. We check that there are no open cavities, leaking fillings or inflamed gums: the gel would get in there and cause pain. Together we record your starting shade on the shade guide, so you can compare the result.

It's important to know that fillings, crowns and veneers don't whiten. If you have any of these where they show, we discuss beforehand whether they will need to be redone in the new shade after whitening.

The three methods at a glance

In-clinic whitening

The dentist protects your gums with a barrier, applies the whitening gel to your teeth and activates it with a special lamp. The session takes about an hour. Depending on your starting shade, a second session is sometimes needed to reach the result you want. Some patients have temporary sensitivity to cold for a day or two. The price is 1,400 lei.

Laser whitening

The gel is activated with a laser, in less time and without heating the tooth. It is the gentlest method for the enamel, and sensitivity afterwards is rare. In most cases a single session is enough. The colour settles within 24 to 48 hours. The price is 1,900 lei.

At-home whitening with trays

We take impressions of your teeth and make thin trays that are custom-fitted to you. At home you put a lower-concentration gel in them and wear them for a few hours a day, for 10 to 14 days. The result comes gradually, which suits people who prefer to set their own pace. You keep the trays for later top-ups. The price is 1,900 lei.

MethodTime neededPrice
In-clinic whiteningone hour, sometimes two sessions1,400 lei
Laser whiteningusually a single session1,900 lei
At-home whitening10 to 14 days, a few hours a day1,900 lei
Whitening a non-vital toothper session350 lei

Sensitivity after whitening and how we prevent it

After in-clinic whitening, some patients feel brief sensitivity to cold or air, like a sharp “twinge” in the tooth. It happens because the gel temporarily opens the pores of the enamel, and it goes away on its own within 24 to 48 hours. We prevent it by first applying a desensitising gel to teeth whose necks are already exposed at the gumline, and by recommending a toothpaste for sensitive teeth for a week before and after. With laser whitening sensitivity is rare, which is why we recommend it to patients whose teeth are naturally sensitive.

What results you can expect

Teeth usually become 4 to 8 shades lighter on the shade guide. Yellowish teeth respond best. Greyish teeth, for example after certain antibiotics taken in childhood, are harder to whiten; for them, veneers may be a better solution. A tooth that has darkened after root canal treatment can be whitened from the inside, in separate sessions.

The first 48 hours after whitening

Right after whitening, the enamel is more porous and easily soaks up pigments. For two days we recommend a “white diet”:

  • no coffee, black tea, red wine or coloured soft drinks;
  • no tomato sauces, curry, beetroot or berries;
  • no smoking;
  • water, milk, yoghurt, rice, pasta, white meat and white bread are all fine.

How long the results last

On average 2 to 4 years, depending on your habits. Drinking coffee several times a day and smoking shorten this considerably. A professional cleaning every 6 months removes new stains and helps the colour last. After 2 or 3 years, a top-up session or a few days with your home trays bring back the shade you achieved.

Who shouldn't whiten their teeth

  • pregnant or breastfeeding women;
  • young people under 18, whose pulp chamber is still large;
  • people with untreated tooth sensitivity or an allergy to the ingredients of the gel;
  • patients with cavities, inflamed gums or unfinished treatment, until these have been dealt with.

Whitening kits from the internet: why we advise against them

Whitening kits bought online either have a concentration too low to have any effect, or an uncontrolled one that can irritate the gums and cause severe sensitivity. One-size-fits-all trays don't fit your teeth, so the gel ends up on your gums. Whitening done by a dentist costs more, but it is safe, predictable and lasts for years.

Frequently asked questions

Does whitening damage the enamel?

No, not when it is done professionally, with a correctly dosed gel and with the gums protected. Laser whitening is the gentlest option.

How many shades lighter will my teeth get?

Usually 4 to 8 shades on the shade guide, depending on your starting colour. Yellowish teeth respond best.

Can I have whitening if I have crowns or veneers?

Yes, but the crowns and veneers themselves won't change colour. We discuss beforehand whether they will need to be redone to match the new shade.

Does whitening hurt?

No. Some patients feel temporary sensitivity to cold for a day or two after in-clinic whitening. With laser whitening it is rare.

Questions about your own case? At the consultation you get a concrete answer and a written plan.

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