Grey Tooth: Why It Turned That Colour and How It's Fixed

Why a Tooth Turns Grey

Tooth colour comes mostly from the layer under the enamel, called the dentine, and the living nerve inside keeps that layer healthy and light. When the nerve dies, that changes. The blood inside it breaks down, and the pigment seeps into the dentine and darkens it, the same way a bruise changes colour under the skin. From the outside the tooth turns grey, greyish-brown, or sometimes almost black.

So grey is not a surface stain you can scrub off. It is coming from inside the tooth, in the dentine, which is why whitening toothpaste and strips do nothing for it. The colour is the visible end of something that happened to the nerve, and what happened decides whether the tooth needs treating.

Grey After a Knock or Injury

A tooth that goes grey weeks or months after a bang to the mouth is the classic case. A knock can damage the tiny blood vessels feeding the nerve, and the nerve slowly dies afterward, even if the tooth felt fine at the time. This is very common with front teeth, and it happens to children and adults alike after a fall, a sports knock, or a collision.

Two things are worth knowing. A tooth can bruise and go grey and then recover its colour over a few weeks as it settles, so a freshly discoloured tooth after an injury is not automatically dead. But if it stays grey, the nerve has usually died and the tooth needs checking, because a dead nerve can quietly become infected. If a child's baby tooth turns grey after a knock and there is no pain, swelling, or bump on the gum, it often just needs watching rather than emergency treatment. Our guide to the signs of a dead tooth covers how a nerve dies without much warning, and a cracked tooth can do the same thing.

Grey After a Filling or a Root Canal

Grey that shows up after dental work usually has one of two explanations. After a deep filling, the tooth can darken if the nerve underneath was already struggling and later dies, or occasionally from a metal filling showing through a thin tooth. A tooth that goes grey after a filling and starts to ache or throb is worth having checked, because the nerve may have given up.

After a root canal, a little darkening is common and usually just cosmetic. The nerve is already gone, that is the whole point of the treatment, so the tooth no longer has its living colour, and traces of old tissue or filling material inside can tint it over time. A tooth that turns grey after a root canal is very rarely a sign the treatment failed; it is almost always a colour issue, and it can be fixed. Our guide to a discoloured tooth after a root canal goes into that case in detail.

Does a Grey Tooth Mean It Needs Treating?

Sometimes, and it depends on why it went grey. The colour on its own is a cosmetic problem. The real question underneath it is whether the nerve is dead and whether that dead nerve is infected, because that is the part that matters for the tooth, not the shade.

The tooth wants seeing, not just watching, if the grey comes with any of these:

• Pain, tenderness to bite on, or a throb that comes and goes.
• A pimple or bump on the gum near the tooth, or a bad taste that keeps returning.
• Swelling of the gum, cheek, or face on that side.
• The tooth feeling loose or different from its neighbours.

Any of those suggests the dead nerve has become infected, and that needs a root canal to clean it out, not a whitening treatment. Waiting to see whether a grey tooth sorts itself out is usually the more expensive choice, because a dead nerve does not come back to life, and left long enough it can turn into an abscess. Our guide to what a tooth abscess is explains how a dead tooth can become infected with barely any pain.

How a Grey Tooth Is Fixed

Once any infection is dealt with, the colour itself has good fixes, and the right one depends on the tooth:

• Internal bleaching. For a tooth that has had a root canal, whitening gel can be placed inside the tooth, where the stain actually is, and left to lighten it from within. This is often the simplest fix and keeps your own tooth.
• A veneer. A thin shell bonded over the front of the tooth covers the grey and matches it to the teeth around it. A good option for a front tooth that does not respond to bleaching.
• A crown. If the tooth is also weak or heavily filled, a crown covers it completely and deals with the strength and the colour together.

Which one fits depends on why the tooth is grey, whether it has had a root canal, and how strong it is, so it is a conversation after an exam, not a one-size answer.

When to Get a Grey Tooth Seen

A grey tooth on its own, with no pain or swelling, is not a middle-of-the-night emergency, but it is not something to ignore for years either. Book to be seen when a tooth has turned or stayed grey, especially after a knock, so the nerve can be checked and the colour sorted before it settles in deeper. A grey front tooth that is bothering you cosmetically is a perfectly good reason to come in on its own.

What is not a dental appointment at all: swelling spreading toward your eye or down your neck, a fever with a swollen face, or any trouble breathing or swallowing. Go straight to a hospital emergency room, because a spreading infection is dangerous whatever tooth started it. Our guide to when a toothache is a real emergency helps you tell the difference.

If a tooth has turned grey, especially after a knock or old dental work, call or WhatsApp 055-985-8845 and we will check whether the nerve is dead or infected and talk through how to fix the colour. We are in Ramat Beit Shemesh, open Sunday to Thursday 8:00 AM to 8:00 PM and Friday 8:00 AM to 2:00 PM, with after-hours emergency treatment outside those hours. Send a photo of the tooth if it is easier. Our root canal treatment page explains how we treat a tooth whose nerve has died.

For guidance from sources with nothing to sell, the ADA's MouthHealthy explains what a dental abscess is and why it needs treating, and the American Association of Endodontists covers what happens to a tooth after an injury and how a root canal clears a dead nerve.