A discoloured tooth can result from surface staining, tooth decay, trauma, changes inside the tooth, or natural ageing. The colour alone cannot confirm the cause.
A tooth can change colour for several very different reasons. Yellowing is often linked to staining or thinner enamel, while one grey or black tooth can point to a problem inside the tooth. Decay can also create dark areas on the surface. The right treatment depends on what caused the colour change, not simply how the tooth looks.
Key Takeaways
- Yellowing is often linked to staining, enamel thinning or natural tooth colour.
- A single grey or black tooth can indicate trauma, decay or changes to the nerve.
- Sudden, painful or worsening discolouration should be assessed by a dentist.
- Whitening works better for some surface stains than for discolouration that starts inside the tooth.
What Does a Discoloured Tooth Mean?
A discoloured tooth does not always mean there is a dental problem. The colour can give a clue about where the discolouration comes from, as:
- Yellow or brown can reflect surface staining, natural tooth colour or thinner enamel
- Grey can indicate changes inside the tooth, often after trauma or nerve damage
- Black can result from severe staining, decay or damaged tooth structure
These colours can develop for different reasons, so other signs can help explain the change. Yellowing is often linked to tea, coffee, red wine, curry sauces or tobacco. It can also become more noticeable when thinner enamel allows more of the naturally yellow dentine underneath to show through. Several teeth becoming yellow or brown gradually is more consistent with external staining.
Grey discolouration is more likely to involve changes inside the tooth. Previous trauma can damage the pulp and cause gradual darkening, sometimes long after the original injury. Previous dental treatment can also affect the colour.
Black discolouration can have several causes, including severe staining, decay or damaged tooth structure. Pain, swelling, sensitivity or a visible hole alongside the colour change can point towards decay or infection.
A sudden colour change or discolouration affecting only one tooth should be checked by a dentist. Colour provides a useful clue, but cannot confirm the cause on its own.
What Can Cause a Tooth to Change Colour?
Tooth colour can change on the surface or from within the tooth. Looking at where the discolouration appears and how it developed can help identify the likely cause.
Tooth Decay
Untreated decay can cause brown or black areas where the tooth structure has broken down. The dark colour may appear around a cavity or within damaged tooth tissue.
Decay is also common in England. The 2023 Adult Oral Health Survey found that 41% of adults with natural teeth had obvious decay on clinical examination, while 64% had signs of decay when enamel level changes were included.
This means a dark area should not automatically be assumed to be staining. If the discolouration is accompanied by a hole, rough area, sensitivity or pain, decay may be contributing to the change and the tooth should be assessed by a dentist.
Surface Staining
Tea, coffee, red wine, curry sauces and tobacco can leave stains on the outer surface of teeth. These stains usually affect several teeth rather than one isolated tooth.
Smoking has a particularly clear link with reported discolouration. A UK national study of 6,000 adults found that 28% of smokers reported moderate to severe tooth discolouration, compared with 15% of non smokers.
This makes surface staining more likely when several teeth gradually become yellow or brown, particularly if you regularly consume staining foods and drinks or smoke. Because these stains are on the outside of the tooth, they may respond well to professional cleaning or whitening, depending on the cause.
Tooth Injury or Trauma
A knock to a tooth can damage the pulp and the blood vessels inside it. The tooth may then become darker over time, even when there is no obvious crack on the outside.
The colour change does not always happen immediately. A tooth can darken months or even years after an injury.
Changes Inside the Tooth
A damaged or dead nerve can make one tooth turn grey or black from within. Blood breakdown products can move into the dentine and create the darker colour.
This type of change is different from ordinary surface staining. It may also happen without obvious pain, particularly after an old injury.
Age Related Changes
Teeth naturally change colour as you get older. Enamel becomes thinner over time, allowing more of the naturally yellow dentine underneath to show through.
That gradual change does not necessarily mean anything is wrong. A sudden or uneven change still deserves a dental assessment.
Why Is Only One Tooth Turning Grey or Black?
When one tooth changes colour while the others remain similar, the cause is often specific to that tooth. Previous trauma is a common possibility, especially if the injury happened some time ago.
Decay, changes to the pulp or nerve and previous root canal treatment can also darken an individual tooth. The tooth may not hurt, so the absence of pain does not rule out an internal problem.
A localised change is therefore worth checking rather than treating as ordinary staining.
When Should You See a Dentist About a Discoloured Tooth?
Certain changes should be checked rather than monitored at home. Sudden discolouration, pain, trauma, swelling or a colour change that continues to worsen are all useful reasons to arrange an assessment.
Sudden Colour Change
A tooth that changes colour suddenly should be assessed, especially when there is no obvious staining trigger. This is more important when only one tooth has changed.
The timing can help your dentist work out whether the change may be linked to trauma, decay or an internal problem.
Pain or Sensitivity
Discolouration with pain or sensitivity suggests that something more than surface staining may be happening. The tooth may need an internal examination to identify the source.
Persistent sensitivity should not simply be treated with whitening products.
Tooth Damage or Trauma
Any colour change after an injury should be checked, even when the tooth feels normal. Damage to the pulp is not always painful at first.
An old knock can still explain a grey tooth years later.
Swelling or a Gum Lump
A discoloured tooth with gum swelling or a lump can indicate infection around the tooth. This combination needs prompt dental assessment.
The swelling may be close to the affected tooth even when the tooth itself does not feel particularly painful.
A Colour Change That Does Not Improve
Discolouration that remains or becomes darker over time should be assessed professionally. This is especially important when cleaning does not change the appearance.
Once we identify the cause, we can advise whether the tooth needs treatment for the underlying problem or whether cosmetic treatment may help improve its appearance. Our cosmetic treatments can help improve the appearance of suitable teeth, but the right option depends on why the tooth has changed colour.
Can a Grey, Yellow or Black Tooth Be Whitened?
Whether a discoloured tooth can be whitened depends mainly on whether the discolouration is on the surface or inside the tooth. Surface staining usually responds better to whitening, while internal discolouration can be harder to lighten.
The likely response to whitening can vary depending on the cause, like:
- Surface staining from food, drinks or tobacco generally responds better to professional whitening
- Internal discolouration caused by trauma, nerve damage or previous root canal treatment may respond poorly to ordinary whitening
A single grey or black tooth should therefore be assessed by a dentist before whitening is considered. The cause needs to be identified first, as whitening may not be the right treatment for internal discolouration.
In the UK, tooth whitening is considered the practice of dentistry, so it can only legally be provided by a registered dental professional. Section 38 of the Dentists Act 1984 makes it an offence for someone who is not registered or otherwise legally entitled to practise dentistry to provide dental treatment. This is why tooth whitening should be carried out through a registered dental professional rather than an unqualified provider.
How Is a Discoloured Tooth Treated?
Treatment for a discoloured tooth depends on what is causing the colour change. The options can include:
- Treating decay or infection first
- Using professional whitening for suitable surface stains
- Treating internal problems affecting the tooth
- Considering cosmetic treatment when the tooth is healthy
A tooth affected by deeper internal discolouration may need restorative treatment instead. Depending on the tooth, this can include bonding, veneers or other cosmetic approaches rather than standard whitening.
Tooth whitening is regulated as dental treatment in the UK. The General Dental Council states that only registered dental professionals can provide whitening treatment, and products containing or releasing between 0.1% and 6% hydrogen peroxide are subject to specific restrictions.
For surface or mild discolouration, teeth whitening may be suitable after the tooth has been checked.
FAQs
Why is my tooth turning grey?
A grey tooth can result from previous trauma, nerve damage or previous dental treatment. A dentist can identify the cause.
Why is my tooth turning black?
Black discolouration can come from decay, severe staining or damaged tooth structure. Pain or swelling makes prompt assessment more important.
Why are my teeth turning yellow?
Yellowing can come from surface stains, natural tooth colour or thinner enamel exposing the yellow dentine underneath.
Can a grey tooth turn white again?
Sometimes, but it depends on the cause. Internal discolouration may not respond well to standard whitening.
Can a black tooth be saved?
Often, depending on how much healthy tooth structure remains and whether the underlying problem can be treated.
Does a grey tooth mean the tooth is dead?
Not always. A grey tooth can follow trauma or previous treatment, so an examination is needed to determine the condition of the pulp.
Conclusion
A discoloured tooth can come from staining, decay, trauma, ageing or changes inside the tooth. The colour can offer clues, but it cannot confirm the cause. Sudden, painful or persistent changes should be assessed before cosmetic treatment is considered. The right treatment depends on what has caused the discolouration.
Book an appointment to have your discoloured tooth assessed.
