Tooth Discolouration (Stains): Causes and How to Remove Them

Tooth discolouration falls into two main types: extrinsic stains that build up on the surface of the tooth — from coffee, tea, red wine and smoking — and intrinsic discolouration that comes from within the tooth, caused by injury, certain medications or age-related changes. The right treatment depends on the cause: surface stains often lighten with professional cleaning or whitening, while internal discolouration may call for restorative solutions such as veneers.

Extrinsic stains are treated with professional cleaning and teeth whitening, whereas internal colour changes are usually resolved with a veneer or a crown — an examination will show which option suits you.

The main types of discolouration

Extrinsic (surface) stains

These build up on the outer layer of the tooth — the enamel. The main causes are:

• Coffee, tea, red wine and dark-coloured drinks.
• Cigarettes and tobacco products.
• Certain dark-coloured foods (berries, sauces).
• Build-up of plaque and tartar.

Intrinsic discolouration

This occurs within the inner structure of the tooth (the dentin) and does not lighten with surface cleaning:

• Darkening of a tooth following an injury (trauma).
• The effect of certain antibiotics taken in childhood (e.g. tetracycline).
• Excess fluoride (fluorosis) in some cases.
• Thinning of the enamel with age, allowing the dentin underneath to show through.
• Colour changes in teeth that have had root canal treatment.

How is the cause identified?

Only a dentist can determine the type of discolouration accurately, through an examination. Surface stains are usually even across all the teeth and yellowish-brown in colour; the darkening of a single tooth, on the other hand, often points to an internal cause (a past injury, for example). An accurate diagnosis makes it possible to choose the right treatment.

Ways to remove discolouration

• Professional cleaning: removes plaque and tartar and lightens many surface stains along with them; it is part of a preventive check-up.
• Teeth whitening: effective for surface stains and some internal discolouration. For a safe result, it is recommended that it be carried out under a dentist's supervision.
• Veneers or bonding: an aesthetic solution that covers the appearance of the tooth when internal discolouration does not respond to whitening.
• Teeth that have had root canal treatment: internal whitening or covering techniques may be considered.

The choice of treatment is tailored to the cause of the discolouration, the condition of the tooth and your expectations.

Prevention

• Cut down on dark-coloured drinks, or rinse your mouth with plain water afterwards.
• Avoid smoking — it is a very common cause of discolouration.
• Brush twice a day with a fluoride toothpaste and use dental floss.
• Schedule regular professional cleanings and check-ups.

These steps help to slow the build-up of new surface stains, but they do not reverse existing internal discolouration.

Questions and Answers (FAQ)

Do all tooth stains go away with whitening? No. Whitening mainly works on surface stains and some internal discolouration. Colour changes caused by trauma, certain medications, or fillings and crowns may not respond to whitening; in these cases, solutions such as veneers are considered.

Why does a single tooth darken? The darkening of one tooth is often linked to a past injury or to root canal treatment on that tooth. This is internal discolouration and requires a separate approach — an examination with a dentist is recommended.

Are at-home whitening products safe? Over-the-counter products may have a mild effect, but incorrect use can cause tooth sensitivity and gum irritation. For a safer and more predictable result, supervision by a dentist is recommended.

Does professional cleaning whiten the teeth? Cleaning lightens surface stains by restoring the tooth's own natural colour, but it is not chemical whitening. If you would like a lighter shade, whitening is discussed separately.

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Clinical note: This article is for general information and does not replace individual advice from your dentist. To find the right option for the colour of your teeth, book an appointment or contact your dentist.

Sources: Peer-reviewed dental literature on aesthetic dentistry and discolouration. The clinical content is based on Dr. Nuran's experience.