Tooth discolouration is common, and it is not all the same. Some stains sit on the surface and polish away; others lie within the tooth itself. Knowing the cause helps predict which treatment is likely to work — and occasionally reveals a problem that needs attention.
The short answer
Tooth discolouration may be extrinsic (surface stain from food, drink or tobacco), intrinsic (within the tooth, from trauma, certain medications, excess fluoride or developmental factors), or age-related (enamel thinning so yellower dentine shows through). Different causes respond to different treatments.
Extrinsic (surface) stains
Extrinsic stains build up on the outer surface of enamel. Common causes include:
- Coffee, tea and red wine, which contain pigmented compounds called tannins
- Cola and dark sauces, such as soy or curry
- Tobacco and shisha, which leave yellow-brown deposits
- Certain mouthwashes, notably chlorhexidine with prolonged use
- Plaque and tartar, which absorb pigments
A professional clean and polish often removes much of this staining. Whitening can lighten what remains.
Intrinsic discolouration
Intrinsic discolouration lies within the tooth structure and cannot be polished away.
Trauma
A knock to a tooth can damage its pulp (nerve). Over time, the tooth may darken to grey or brown. A single darkening tooth should always be examined, because it can indicate that the pulp has died and may need root canal treatment.
Medications
Tetracycline antibiotics taken while teeth are forming (in pregnancy or childhood) can cause grey, brown or banded discolouration. Some other medications have also been associated with tooth discolouration.
Fluorosis
Excess fluoride while teeth are developing can cause white flecks, streaks or, in more severe cases, brown patches.
Developmental conditions
Inherited conditions affecting enamel or dentine can alter tooth colour and texture.
Old restorations
Metal fillings can make teeth appear grey; old tooth-coloured fillings can discolour at their edges.
Age-related changes
Over time, enamel gradually thins through wear, and the underlying dentine — which is naturally more yellow — becomes more visible. Teeth may also accumulate stain over decades.
When discolouration needs a check
Seek a dental assessment if:
- A single tooth darkens
- You notice brown or black spots, which can indicate decay
- White patches appear near the gum line, which can be early decay
- Discolouration is accompanied by pain or sensitivity
Matching causes to treatments
| Cause | Options that may help |
|---|---|
| Surface stain | Professional cleaning, then whitening |
| Age-related yellowing | Professional whitening |
| Single dark tooth after trauma | Assessment, possible root canal treatment, internal bleaching, veneer or crown |
| Tetracycline staining | Extended whitening, veneers |
| Mild fluorosis | Microabrasion, resin infiltration, bonding |
| Old restorations | Replacement with tooth-coloured restorations |
Preventing discolouration
- Brush twice daily with fluoride toothpaste and clean between teeth
- Rinse with water after coffee, tea or dark drinks
- Avoid tobacco and shisha
- Attend regular check-ups and professional cleaning
Conclusion
Identifying the cause of discolouration is the first step towards an effective treatment. Many surface stains respond well to cleaning and whitening; others may need different approaches. A dental assessment can explain what is behind your tooth colour and which options suit you. Learn about professional whitening and veneers.
Frequently asked questions
Why is one of my teeth darker?
It can be due to past trauma or nerve changes. It should be examined.
Sources and further reading
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