Why teeth change colour
Teeth darken for two kinds of reasons, and they respond to treatment differently:
- Surface stains from tea, coffee, paan, tobacco and some foods. A professional clean removes much of this, and whitening lifts the rest.
- Colour inside the tooth, from ageing, an old injury, a root-canal-treated tooth, some antibiotics taken in childhood, or fluorosis. Ageing responds well to whitening. Deep grey or patchy stains may need veneers or bonding, often combined with whitening the other teeth.
In-clinic or take-home whitening
| In-clinic whitening | Take-home trays | |
|---|---|---|
| How it works | A stronger gel applied by the dentist, with the gums protected | A milder gel in custom trays you wear at home |
| Time | One visit of about 60–90 minutes | Daily for about 2–3 weeks |
| Result | A visible change in one visit | Gradual, even and often longer lasting |
| Sensitivity | More likely for a day or two | Usually milder |
| Touch-ups | Repeat visit | Keep the trays and top up when needed |
What happens
- Check-up and clean. We check for decay, worn fillings and gum problems, and clean the teeth so the gel works evenly.
- Shade record. Your starting shade is recorded with photographs so you can see the change.
- Whitening. For in-clinic whitening, the gums are covered with a protective barrier and the gel is applied in timed rounds. For take-home whitening, we scan or take impressions for your custom trays and show you how to use them.
- Review. We compare the new shade with the start and plan any touch-ups, or the replacement of visible fillings so they match.
Aftercare
- Avoid strongly coloured food and drink and smoking for 48 hours.
- Use a sensitivity toothpaste if your teeth feel twingy.
- Brush twice daily and keep your regular cleans to slow new staining.
- Keep your trays; a short top-up every so often keeps the shade.
Risks
Temporary sensitivity and mild gum irritation are the common side effects and settle within a few days. Over-the-counter strips, charcoal powders and DIY remedies such as lemon or baking soda can wear enamel or burn the gums, which is why whitening is best done under a dentist’s care. Results vary from person to person, and your cosmetic dentist will tell you what change to expect for your teeth.
What affects the fee
In-clinic, take-home or both, the number of sessions, whether a clean is needed first, and whether any fillings or crowns will be replaced afterwards to match. You get the fee after your check-up.
Questions patients ask us
Is teeth whitening safe?
Yes, when it's carried out or supervised by a dentist. The gel lightens the colour of the tooth without damaging the enamel. The gums are protected during in-clinic whitening, and take-home trays are made to fit your teeth so the gel stays where it should.
Does teeth whitening hurt?
Whitening itself isn't painful. Some people feel sensitivity or brief twinges for a day or two afterwards. A sensitivity toothpaste for a couple of weeks beforehand, and spacing out take-home sessions, help a lot.
How long does teeth whitening last?
Usually from several months to a few years. Tea, coffee, red wine, paan, turmeric-heavy food and smoking bring the stains back sooner. Keeping your trays for a short touch-up every so often keeps the result.
In-clinic or take-home whitening, which is better?
In-clinic whitening gives a visible change in one visit. Take-home trays work more gradually and often give a more even, longer-lasting result with less sensitivity. Many people get the best result from a combination of the two.
Will whitening work on my crowns, fillings or veneers?
No. Whitening only changes the colour of natural teeth. If you have visible crowns or fillings, we plan whether to replace them after whitening so everything matches.
Does scaling whiten teeth?
Scaling removes tartar and surface stains, so teeth often look brighter afterwards, but it doesn't change the natural colour of the tooth. Whitening does. We usually do a clean before whitening for the best result.
What should I avoid after teeth whitening?
For the first 48 hours, avoid strongly coloured food and drink such as tea, coffee, cola, red wine, curries with turmeric and beetroot, and don't smoke. Teeth pick up stains most easily just after whitening.
Who shouldn't have teeth whitening?
Whitening isn't usually advised for children and teenagers, or during pregnancy and breastfeeding. Decay, leaking fillings and gum disease are treated first, because whitening over them causes pain and doesn't last.
Sources
NHS: teeth whitening ↗ADA MouthHealthy: teeth whitening ↗Last updated 14 October 2026. This page explains options in general terms; your own plan comes from an examination.