Tooth Turning Grey or Dark: Causes and Treatment Options

Noticing that one of your teeth has turned grey, dark, or a different shade from the rest can be alarming. A single discoloured tooth is a surprisingly common concern, and while it's not always a sign of something serious, it's worth understanding what might be causing it. In some cases, it does need treatment.

Why Has My Tooth Changed Colour?

When a single tooth becomes noticeably darker than the others, the cause is usually one of the following:

Trauma and a Dead Nerve

This is the most common reason a single tooth turns grey or dark. A knock or blow to the tooth — even one that happened years ago — can damage the nerve (pulp) inside. When the nerve dies, the blood supply breaks down and blood pigments gradually seep into the dentine, causing the tooth to darken over time. You might not have experienced any pain at the time of the injury, which is why the discolouration can seem to appear out of nowhere.

Root Canal Treatment

Teeth that have had root canal treatment can sometimes darken afterwards. The removal of the nerve and blood supply means the tooth no longer receives the same nourishment, which can lead to gradual colour change. Some materials used during root canal treatment can also contribute to discolouration.

Silver Amalgam Fillings

Old silver amalgam fillings can stain the surrounding tooth structure, giving the tooth a grey or bluish appearance. The metal compounds in the filling gradually leach into the dentine over years. The tooth itself may be perfectly healthy — it's simply been stained by the filling material.

Other Causes

• Tetracycline staining: Antibiotics taken during childhood (when teeth were developing) can cause characteristic grey-brown or yellow-brown bands across multiple teeth
• Decay: Advanced tooth decay can cause dark spots or patches, sometimes making the whole tooth appear darker
• Age-related changes: Teeth naturally darken with age as the enamel thins and the darker dentine beneath becomes more visible
• Fluorosis: Excessive fluoride during tooth development can cause white or brown patches

Concerned about a dark tooth? Search for dentists near you who can assess the cause and discuss your options.

When a Dark Tooth Means the Nerve Is Dead

If a single front tooth is gradually turning grey or dark and you have a history of trauma to that area, there's a good chance the nerve inside has died. Your dentist can confirm this with tests — typically checking the tooth's response to cold and taking an X-ray to look at the root.

A dead tooth doesn't always cause pain, but it does need treatment. Without a functioning blood supply, the tooth is more vulnerable to infection at the root tip, which can lead to a dental abscess if left untreated.

Treatment Options

The right treatment depends on the cause. Here are the main options available in the UK:

Internal Bleaching (Walking Bleach)

If the tooth has had root canal treatment (or needs one), your dentist can place a whitening agent inside the tooth and seal it in for one to two weeks. This process, sometimes called "walking bleach," can significantly lighten the tooth from the inside. It may need to be repeated once or twice for best results. This is often the most conservative and cost-effective option for a single dark tooth.

Porcelain Veneer

A thin shell of porcelain bonded to the front of the tooth can mask discolouration effectively. Veneers are particularly useful for front teeth where appearance matters most. They typically require some enamel to be removed and are mainly a private treatment option.

Dental Crown

If the tooth has significant structural damage or a large filling alongside the discolouration, a crown may be the best option. A crown covers the entire visible portion of the tooth, restoring both appearance and strength. Crowns are available on the NHS if clinically necessary.

Composite Bonding

For milder discolouration, tooth-coloured composite resin can be applied to the surface to improve appearance. This is less invasive than a veneer or crown, though may not mask severe darkening as effectively.

Cosmetic vs Clinical: When Does It Need Treatment?

Not every discoloured tooth requires treatment. Here's how to think about it:

• Needs clinical treatment: If the nerve is dead (tooth needs root canal to prevent infection), or if decay is causing the discolouration
• Cosmetic choice: If the tooth is healthy but stained by an old filling, tetracycline, or age-related changes — treatment is optional and based on your preference
• Worth monitoring: If a tooth has had recent trauma and is slightly changing colour, your dentist may want to review it periodically, as the nerve may still recover

Cost Guidance

On the NHS, root canal treatment and a crown fall under Band 2 (£75.50) if clinically required. Cosmetic treatments such as internal bleaching and veneers are generally only available privately:

• Internal bleaching: £100 to £350 per tooth (private)
• Composite bonding: £100 to £400 per tooth (private)
• Porcelain veneer: £400 to £1,000+ per tooth (private)
• Crown: £300 to £900+ privately, or NHS Band 2 if clinically needed

Many practices offer payment plans to help spread the cost of cosmetic treatments. It's also worth noting that standard teeth whitening won't work on a dead tooth — external bleaching only affects living teeth with an intact blood supply.