Tooth discolouration falls into two main types: extrinsic staining on the surface of the tooth, and intrinsic staining that sits within the tooth structure itself. Knowing which type you have matters, because it decides what will actually work. Surface stains often respond to cleaning and whitening, while stains built into the tooth need different approaches. Most discolouration is harmless, but a single tooth that darkens on its own is worth checking.
Key takeaways
- Extrinsic discolouration is surface staining from food, drink, and smoking, and usually responds to cleaning and whitening.
- Intrinsic discolouration comes from within the tooth and is caused by things like fluorosis, certain medicines, injury, or ageing.
- The single most important step is identifying which type you have, since it determines the right treatment.
- Whitening works well on many stains but not on all, and it does not change the colour of fillings, crowns, or veneers.
- A single tooth going grey or dark, especially after a knock, should be assessed, as it can mean the nerve has died.
Extrinsic staining: on the surface
Extrinsic stains sit on the outside of the enamel. They come from coloured foods and drinks such as coffee, tea, red wine, and dark sauces, from tobacco, and from a build-up of plaque and tartar. These are the stains that a professional clean lifts, and that surface whitening is designed for. Because they are on the surface, good daily cleaning and reducing staining habits go a long way to preventing them. Our guide to enamel erosion explains how a thinned enamel surface can also make teeth look more yellow, since the darker dentine underneath shows through.
Intrinsic staining: within the tooth
Intrinsic discolouration is built into the enamel or the dentine beneath it, so it cannot be brushed or scaled away. Common causes include dental fluorosis, which produces white flecks or brown mottling from too much fluoride while the teeth were forming, and certain medicines taken during tooth development, most famously the antibiotic tetracycline, which can leave grey or brown bands. A knock to a tooth can cause it to darken as the nerve is affected, and teeth also naturally yellow a little with age as the enamel thins and the dentine darkens. Conditions affecting enamel or dentine formation can also change colour from the start. Our guides to dental fluorosis and white spots on teeth cover two of these in detail.
The single rule that decides treatment
The one principle to hold onto is that treatment follows the type. Trying to whiten a stain that is not responsive, or scrubbing at discolouration that lives inside the tooth, wastes effort and can do harm. A dentist works out whether the colour is on the surface or within, whether it affects all the teeth or just one, and whether there is an underlying cause such as a dead nerve. That assessment points to the treatment that will genuinely help.
| Type | Common causes | Approaches that tend to help |
|---|---|---|
| Extrinsic (surface) | Coffee, tea, wine, smoking, tartar | Professional clean, whitening, reducing staining habits |
| Intrinsic (internal) | Fluorosis, tetracycline, injury, ageing | Whitening in some cases, microabrasion, bonding, veneers |
| Single dark tooth | Nerve damage after a knock | Assessment, sometimes internal whitening or a crown |
What treatments are available
Surface stains usually respond well to a professional clean and to whitening. For milder intrinsic discolouration, whitening can still help, and enamel microabrasion, which gently removes a very thin surface layer, can improve certain white or brown marks. Deeper or banded intrinsic staining, such as strong tetracycline staining, is often better managed with bonding or veneers that mask the colour, since whitening alone may not be enough. A single dark tooth from a dead nerve may need different treatment, sometimes internal whitening or a crown. Importantly, whitening only changes natural tooth structure, so any fillings, crowns, or veneers keep their original colour and may need replacing to match a whiter smile. Our guides to crowns versus veneers and bonding versus veneers compare the cosmetic options.
General cost guide
Costs depend on the type of discolouration and the chosen treatment. The figures below are general market ranges across Australian clinics, not a Lumi quote.
| Item | General cost guide (AUD) |
|---|---|
| Professional clean | $150 to $350 |
| Take-home or in-chair whitening | $250 to $1,000 |
| Composite bonding (per tooth) | $150 to $450 |
| Porcelain veneer (per tooth) | $1,200 to $2,500 |
When to see a dentist
See a dentist if a single tooth darkens, especially after an injury, if discolouration appears suddenly, or if you are unhappy with the colour of your smile and want to know what will actually work. An assessment identifies the type and the most effective option. Whitening is not suitable for everyone, so professional advice avoids disappointment and protects your teeth.
Frequently asked questions
Can all discoloured teeth be whitened?
No. Surface stains and many mild internal stains respond well, but deep intrinsic staining may need bonding or veneers instead. Fillings and crowns do not whiten at all.
Why is one of my teeth darker than the rest?
A single darker tooth often means the nerve inside has been affected, commonly after a past knock. It should be assessed, as it may need specific treatment.
Is tooth discolouration a sign of decay?
It can be. Brown or dark spots in one area may be decay rather than staining, which is another reason to have new discolouration checked rather than assuming it is cosmetic.
Does whitening damage my teeth?
Used correctly under professional guidance, whitening is generally safe, though it can cause temporary sensitivity. Overusing shop bought products can be harmful, so it is best done with advice.
How can I prevent stains coming back?
Clean well twice a day, keep up regular professional cleans, and cut down on coffee, tea, red wine, and smoking. Rinsing with water after staining drinks also helps.
If you would like to know what is causing your discolouration and what will genuinely improve it, the team at Lumi Dental in Melrose Park offers a complimentary cosmetic consultation with a written quote. Learn more about teeth whitening or book a free cosmetic consult.
This article is general information only and is not a substitute for personalised advice from a dental professional. If a tooth darkens or discolouration appears suddenly, please arrange an assessment.
