Teeth whitening: what to know before you start

Whitening lightens the colour of natural teeth. It is a cosmetic choice, and a conversation with your dentist beforehand helps you decide whether it suits your teeth and what to expect.

Why teeth change colour

Teeth can darken or stain with age, with drinks such as tea, coffee and red wine, and with smoking. Some discolouration comes from inside the tooth, for example after an injury or because of certain medicines.

What whitening can and cannot do

• Whitening works on natural tooth surfaces. It does not change the colour of crowns, veneers, caps or fillings.
• Different kinds of discolouration respond differently. Yellowish teeth tend to respond better than brown or grey tones.
• Discolouration caused by an injury or by medicines may not respond.
• The effect is not permanent, and stains can return.

Surface stains can often be reduced with a professional clean or with whitening toothpaste. Toothpaste only removes stain from the surface; it does not change the natural colour of the tooth.

Ways whitening is done

• In the dental surgery, where a whitening gel is applied after your gums are protected, sometimes with a light or laser.
• At home with custom-made trays and gel supplied by a dentist, used as instructed over a period of time.

Whitening products from salons or bought online may not work as well and can harm teeth and gums. Dentists check that your teeth and gums are healthy first, because whitening is not suitable for everyone. It is generally not recommended for young people or during pregnancy or breastfeeding, so ask your dentist.

Possible side effects

Whitening can cause side effects, usually for a short time:

• Teeth that feel sensitive to cold or sweet things
• Sore gums or throat
• Pale patches on the gums

Using whitening products more than directed can damage the enamel or gums. If side effects bother you, pause and talk to your dentist.

Questions to ask your dentist

• Is whitening suitable for my teeth and gums?
• How will my fillings, crowns or veneers look next to whitened teeth?
• Which side effects should I expect, and what should I do if they bother me?
• How should I use any product, and how often?

When to see a dentist

• Before you start, especially if you have fillings, crowns, or very dark or grey stains
• If you already have sensitive teeth, gum problems or suspected decay
• If sensitivity or gum soreness is troubling you during or after whitening
• If one tooth has changed colour on its own

• Learn about Laser Teeth Whitening →
• Book an appointment →

Educational information. It does not replace advice from your dentist or doctor.