Grey tooth after injury: is it dead and what improves its colour?

Key points in brief

• A grey tooth after an injury is sometimes dead, but sometimes it is still alive. The dentist judges this by how the tooth responds to cold, by an X-ray and by whether the grey deepens over time.  
• A dead tooth needs root canal treatment, while a living one most often needs only check-ups. If the colour bothers you, a dead tooth is usually whitened afterwards from the inside, and a living one from the outside.
• Toothache, swelling or a small pimple on the gum is a reason to contact a dentist urgently to conduct an examination. Without these symptoms, a tooth injured long ago does not need an urgent visit, but do not put off having it examined.
• Severe pain that painkillers do not relieve, or facial swelling with a fever, needs help the same day. If swelling makes it hard to breathe or swallow, call the emergency number 112 immediately.
• A veneer, a crown or bonding, which means covering the tooth with composite, is considered only after the diagnosis. Fitted earlier, any of them would hide the colour that helps to tell whether the tooth is alive.

What it means when a tooth turns grey after an injury

A grey tooth after an injury is most often the result of damage to the pulp, the living tissue with nerves and blood vessels inside the tooth. If the tooth has already had root canal treatment, it no longer has a pulp. With a dark tooth after root canal treatment, the dentist checks that treatment and chooses a way to lighten the tooth. With a tooth that has never had root canal treatment, the first step is to find out whether its pulp is alive.

After a recent injury - one from a few hours or days ago - the tooth needs to be seen by a dentist as soon as possible, even if it has not changed colour. A grey baby tooth in a child is assessed on different principles from a permanent tooth, so it is worth showing it to a paediatric dentist.

A grey tooth after an injury may be dead, but its pulp may also still be alive. Grey that deepens over time, or appears only years after the injury, points more towards a dead tooth. Discolouration that appeared in the first weeks after the injury fades on its own in some teeth, over anything from a few months to more than a year. A yellow shade usually means that the pulp chamber, the space inside the tooth that holds the pulp, is gradually filling in with hard tissue. Dentists call this pulp canal obliteration. The tooth then becomes less translucent, and the pulp is most often alive.

A blow can damage the vessels that carry blood to the pulp. When that happens, blood leaks into the pulp, and the products of its breakdown stain the dentine, the tissue that lies beneath the enamel. A dark tooth after a knock can be grey or brownish, and just after the injury it is sometimes pinkish.

If the grey appeared only years later, the pulp may have been dying slowly and without pain, while the pigment built up gradually in the dentine. Such a tooth often causes no symptoms apart from its colour, which is why its condition is easy to overlook.

After an injury the pulp may heal or die, and the pulp chamber may fill in over time. Colour alone does not settle which of these has happened, so a tooth that changed colour after an injury a few years ago also needs an examination.

What you can check before your visit

• Take a photo with your phone in daylight, without the flash, so that the grey tooth and the matching tooth on the other side are next to each other in the frame.
• Look for older photos in which you are smiling.
• Try to remember the injury: when it happened, whether the tooth was loose, moved or chipped at the time, and whether it was treated.
• Notice whether the tooth hurts when you bite and whether swelling or a small pimple appears on the gum next to it. If so, contact a dentist urgently to arrange an examination. With severe pain that painkillers do not relieve, or facial swelling with a fever, get help the same day. If swelling makes it hard to breathe or swallow, call the emergency number 112 immediately or go to a hospital emergency department (SOR).
• If you have earlier X-rays of this tooth, bring them to the appointment.

A phone camera alters shades, so a photo will not replace an examination, but it will show the dentist whether the grey tooth is standing out more and more.

How the dentist plans treating the tooth and improving its colour

The dentist usually works through three questions in turn:

1. Does the tooth hurt, and is there swelling or a pimple on the gum? If so, the dentist first looks for the cause and treats it, and deals with the colour later. If not, the dentist is guided by the test results.
2. What do the cold test and the X-ray show?

• The X-ray shows no change at the root tip, that is, no darker area in the bone, and the tooth responds. Or it does not respond, but its pulp chamber is filling in on the X-ray and the grey is not deepening. The pulp is most likely alive, so what remains is check-ups and, if the colour bothers you, whitening from the outside.
• The tooth does not respond, its pulp chamber is not filling in, and nothing else is a cause for concern. One result is not enough, so the dentist repeats the test after a few months and at later visits. Improving the colour is planned only once it is known whether the tooth is alive.
• At least two of three signs are present: grey that deepens over time, no response to testing, and a change at the root tip that grows on successive X-rays. This is a reason for root canal treatment and then, if the colour bothers you, for whitening from the inside.
• The X-ray shows loss of root tissue. More detailed tests are then needed, sometimes a CT scan.

3. Was whitening enough? If the colour still stands out, the dentist suggests bonding, which means covering the tooth with composite, or a veneer, and for a badly weakened tooth a crown.

With bonding, the dentist applies tooth-coloured composite in layers and usually grinds the tooth only a little or not at all. Bonding is part of restorative treatment, meaning treatment that preserves as much of the tooth's own tissue as possible. Over time, however, composite discolours more easily than ceramic. A veneer or a crown gives a more predictable colour, but the tooth has to be ground down for it, and it will need replacing in the future. A dark tooth is hard to cover whatever the material, so lightening it before bonding or a veneer may make it easier to achieve a natural shade.

How the dentist checks whether the tooth is alive

The dentist looks at several signs together. The first step is to ask about the injury and compare the tooth's colour with its neighbours. Then the dentist checks how the tooth responds to cold, and sometimes to electric testing, which uses a weak current.

Both tests show whether the tooth's nerve responds, but they do not tell whether blood is reaching the pulp. After an injury, the nerve may not respond for weeks or months, even though the tooth already has a blood supply. In some teeth the response returns only after more than a year. That is why no response to cold and electric pulp testing is not, on its own, a reason for root canal treatment.

An X-ray shows what cannot be seen in a mirror. On it, the dentist checks for a darker area in the bone at the root tip, which usually means inflammation around a dead tooth. The X-ray also shows whether the pulp chamber is filling in and whether tooth resorption, the gradual loss of root tissue, has appeared. After an injury, resorption can progress without pain.

Cone-beam CT - a three-dimensional scan of a small part of the jaw - is done when an ordinary X-ray raises a suspicion of resorption, or when a canal that has filled in has to be found before treatment. It is not done routinely, because the scan makes sense only when it can change the treatment plan.

What tells the dentist the most is how the tooth changes from one visit to the next. After more serious injuries, guidelines recommend check-ups once a year for at least 5 years.

What comes next if the tooth is alive, and what if it is dead

If the pulp is alive and the pulp chamber is filling in, root canal treatment is not carried out as long as the tooth does not hurt and the X-ray shows no change at the root tip. In some of these teeth, however, the pulp dies years later, which is why check-ups are recommended. If a living tooth starts to hurt on its own, or reacts to cold for a long time, this may mean inflammation of the pulp, and the dentist then reassesses the tooth.

A living tooth, whether yellow or greyish, is usually lightened from the outside. The dentist makes trays fitted to your teeth, and you put the gel into them at home. The gel may cause temporary tooth sensitivity or irritate the gum, which usually passes after a break or once whitening is finished. A tooth with a living pulp is not whitened from the inside.

The dentist removes a dead pulp during root canal treatment, because over time it may become infected and cause inflammation of the bone around the root tip. After root canal treatment, the tooth can be lightened from the inside. When whitening a dead tooth this way, also called internal bleaching, the dentist seals a whitening agent inside the pulp chamber for a few days and, if needed, replaces it at further visits.

A past injury is linked to a risk of resorption at the neck of the tooth, so the dentist seals off the root canal filling from the whitening agent and keeps checking the tooth after the procedure too. If after whitening the tooth starts to hurt, the gum next to it swells, or a pinkish discolouration appears at the neck of the tooth, see your dentist before the scheduled check-up.

How to keep the colour matching the neighbouring teeth

The colour of a whitened tooth and the colour of composite both change over time. Composite also loses its shine, so bonding may need polishing or a new outer layer.

If you plan to whiten all your teeth, do it before the dentist covers the grey tooth with composite or a veneer. Composite, veneers and crowns cannot be whitened, so their colour is matched to teeth that have already been whitened. At check-ups, compare the colour on photos taken in the same light, because that makes it easier to notice when the grey tooth starts to stand out again.

Where do you start if you have a grey tooth after an injury?

First, show the tooth to a dentist. A veneer or crown fitted before the diagnosis will hide the colour that helps to tell whether the tooth is alive, and may make later tests more difficult. If the tooth is already covered by a veneer or crown and pain or a pimple on the gum has appeared, tell your dentist about the past injury.

Frequently asked questions

Does an injury from many years ago still matter?

An old injury still matters, because some of its effects show up only years later. In some teeth whose pulp chamber is filling in, the pulp dies only after several years, and root resorption can progress without pain. So tell your dentist about an old injury, even if the tooth looks fine. If the colour changes, ask for a comparison with earlier X-rays.

Do I need to mention an old injury before orthodontic treatment?

Yes. Moving a tooth that has been injured is linked to a higher risk of the pulp dying, especially when its pulp chamber has completely filled in. Your orthodontist should know about the injury before planning treatment. It is worth having such a tooth examined before the brace is fitted, and having it checked at later visits during treatment.

Can a grey tooth after an injury be whitened without root canal treatment?

Yes, if tests show that the pulp is alive. Such a tooth is whitened from the outside as your dentist advises, usually at home. In the European Union, products with a higher concentration of hydrogen peroxide are used under a dentist's supervision and not in people under 18. With a dead tooth, root canal treatment is needed first.

Is a grey tooth dangerous if it does not hurt?

A grey tooth may need treatment even when it does not hurt. A dead pulp can become infected without any discomfort, and inflammation around the root tip often causes no symptoms for a long time and shows up only on an X-ray. If the injury was long ago, the tooth does not hurt and there is no swelling or pimple on the gum, the visit is not urgent, but it is not worth putting off the examination.

Can just one grey tooth be whitened?

Yes, although the method depends on whether the tooth is alive. A dead tooth that has had root canal treatment is whitened from the inside, so the procedure involves only that tooth. A living tooth is whitened from the outside with gel in a tray, and the dentist can limit the gel to that one tooth. Whitening strips and toothpastes from the chemist work on all the teeth at once, so they are unlikely to reduce the difference in colour.

Can a tooth darken again after whitening?

After internal bleaching, the tooth may partly darken again over time, so the dentist usually stops whitening when the tooth is slightly lighter than its neighbours. It is not known exactly how long the effect lasts, so the colour is assessed at later check-ups. If the tooth darkens again, whitening can sometimes be repeated.

Read more:

• Aesthetic and Restorative Dentistry in Warsaw
• A dark tooth after root canal treatment: internal tooth bleaching, a veneer or a crown
• Tooth resorption. What is worth knowing?
• Veneers or crowns — when to choose which restoration
• Root canal treatment step by step: How long does it take, what does it look like and what to expect?

Content and liability disclaimer

This article is informational and educational in nature and does not constitute medical advice, a diagnosis or a therapeutic recommendation — it does not replace a consultation with a specialist. If you are experiencing symptoms, have doubts or are facing a decision about treatment, consult a dentist. The methods described and the data cited are general in nature. The results of scientific studies relate to populations, not to an individual patient. The course and outcome of therapy depend on the individual clinical situation and may vary between patients. No information contained in this article constitutes a guarantee of result. The content has been prepared with due care, based on publicly available medical knowledge and the scientific publications indicated in the Sources section. We do not advise taking or refraining from any health-related action solely on the basis of the content of this article, without prior consultation with a doctor.

Sources

Source 1

Links https://doi.org/10.1111/iej.13543 │ https://pubmed.ncbi.nlm.nih.gov/33934366/

Description European Society of Endodontology (ESE) developed by: Krastl G, Weiger R, Filippi A, Van Waes H, Ebeleseder K, Ree M, Connert T, Widbiller M, Tjäderhane L, Dummer PMH, Galler K. „European Society of Endodontology position statement: endodontic management of traumatized permanent teeth.” International Endodontic Journal. 2021;54(9):1473-1481.

Source 2

Links https://doi.org/10.1111/edt.12578 │ https://pubmed.ncbi.nlm.nih.gov/32475015/

Description Bourguignon C, Cohenca N, Lauridsen E, Flores MT, O’Connell AC, Day PF, Tsilingaridis G, Abbott PV, Fouad AF, Hicks L, Andreasen JO, Cehreli ZC, Harlamb S, Kahler B, Oginni A, Semper M, Levin L. „International Association of Dental Traumatology guidelines for the management of traumatic dental injuries: 1. Fractures and luxations.” Dental Traumatology. 2020;36(4):314-330.

Source 3

Links https://doi.org/10.1111/edt.13002 │ https://pubmed.ncbi.nlm.nih.gov/39445627/

Description Tsukiboshi M, Berlin-Broner Y, Levin L. „Transient Apical Breakdown: Incidence, Pathogenesis, and Healing.” Dental Traumatology. 2025;41(Suppl 1):72-79.

Source 4

Links https://doi.org/10.1007/s00784-024-05574-w │ https://pubmed.ncbi.nlm.nih.gov/38430349/

Description Coste SC, Rodrigues MAF, Chaves JFM, Lima TCDS, Colosimo EA, Bastos JV. „A retrospective cohort study of pulp prognosis in luxated permanent teeth: a competing risk analysis.” Clinical Oral Investigations. 2024;28(3):187.

Source 5

Links https://doi.org/10.1111/iej.13916 │ https://pubmed.ncbi.nlm.nih.gov/36942472/

Description Patel S, Krastl G, Weiger R, Lambrechts P, Tjäderhane L, Gambarini G, Teng PH. „ESE position statement on root resorption.” International Endodontic Journal. 2023;56(7):792-801.

Source 6

Links https://doi.org/10.1016/j.joen.2025.09.008 │ https://pubmed.ncbi.nlm.nih.gov/41412684/

Description Sousa Melo SL, Fayad MI, Gohel A, Johnson BR, Kalathingal S, Mahdian M, Nair M, Setzer FC, Makins SR. „AAE and AAOMR Joint Position Statement: Use of Cone-Beam Computed Tomography in Endodontics 2025 Update.” Journal of Endodontics. 2026;52(1):4-13.

Source 7

Links https://doi.org/10.1111/iej.13711 │ https://pubmed.ncbi.nlm.nih.gov/35188275/

Description Kahler B. „Present status and future directions – Managing discoloured teeth.” International Endodontic Journal. 2022;55(Suppl 4):922-950.

Source 8

Links https://doi.org/10.1016/j.joen.2021.10.011 │ https://pubmed.ncbi.nlm.nih.gov/34762968/

Description Frank AC, Kanzow P, Rödig T, Wiegand A. „Comparison of the Bleaching Efficacy of Different Agents Used for Internal Bleaching: A Systematic Review and Meta-Analysis.” Journal of Endodontics. 2022;48(2):171-178.

Source 9

Links https://doi.org/10.1007/s00784-023-05102-2 │ https://pubmed.ncbi.nlm.nih.gov/37335397/

Description Duarte PHM, Weissheimer T, Michel CHT, Só GB, da Rosa RA, Só MVR. „Do orthodontic movements of traumatized teeth induce dental pulp necrosis? A systematic review.” Clinical Oral Investigations. 2023;27(8):4117-4129.