Teeth Whitening

Teeth whitening is a cosmetic dental treatment that lightens the natural colour of teeth using a peroxide-based gel (hydrogen peroxide or carbamide peroxide). The gel penetrates the enamel and breaks down the stain molecules inside the enamel and the underlying dentin, so the tooth reflects more light and looks brighter. It does not remove tooth structure.

Why It Matters

Whitening is the least invasive way to change the shade of a smile, because nothing is drilled or bonded to the teeth. It works best on yellowing caused by ageing, coffee, tea, red wine and smoking. It is less predictable on grey or brown discolouration from medication, trauma or a dead nerve, and it has no effect on crowns, veneers, fillings or dentures. For this reason, whitening is usually planned before any front-tooth restorations, so that new work can be matched to the final shade.

Clinical Details

• In-office whitening: A higher-concentration gel is applied in the dental chair while the gums are protected with a barrier. Some systems, such as Zoom whitening and laser whitening, use a light to activate the gel. Visible change is reached in one appointment.
• At-home whitening with custom trays: The dentist takes a scan or impression and makes trays that fit your teeth. You wear them with a lower-strength gel for a set period each day, usually over a few weeks. Results develop more gradually.
• Combined approach: An in-office session followed by home trays to deepen and maintain the result.
• Shop-bought products: Strips, pens and whitening toothpastes contain much weaker agents or work mainly on surface stains, so the change is smaller. Poorly fitting products can also irritate the gums.
• Assessment first: Decay, leaking fillings, receding gums or worn enamel should be checked and treated before whitening, as they can increase sensitivity.
• Existing restorations: Crowns, veneers and composite bonding keep their original colour. If you plan composite bonding, whitening is normally done first so the composite can be matched to your new shade.
• Regulation (UK): Whitening products above cosmetic strength may only be provided by a registered dental professional and are not used for patients under 18.

FAQ

Is teeth whitening safe?

Professional whitening carried out after a dental check is considered safe for enamel. The most common side effects are temporary tooth sensitivity and mild gum irritation, which usually settle within a few days of finishing treatment.

How long does teeth whitening last?

Whitening is not permanent. Results can last for several years, but stains gradually return, faster if you smoke or regularly drink coffee, tea or red wine. Occasional top-up sessions with your trays help maintain the shade.

Is in-office or at-home whitening better?

Both use the same type of active ingredient. In-office whitening gives a faster visible result, while custom trays at home work more gradually and are easy to use for top-ups. Many patients combine the two.

Does whitening work on crowns or veneers?

No. Whitening only lightens natural teeth. If a crown or veneer no longer matches after whitening, it would need to be replaced to match the new shade.

Why are my teeth sensitive after whitening?

The gel temporarily makes the tooth more permeable to temperature changes. A toothpaste for sensitive teeth and avoiding very cold food and drink for a few days usually helps. Tell your dentist if sensitivity is strong or persists.