Whitening Internal Stains: What to Do for a Grey or Dead Tooth

Noticing that one of your teeth has gradually turned grey or dark can be a worrying experience. It often catches people off guard — perhaps you spot it in a photograph or while brushing one morning, and suddenly you feel self-conscious about your smile. It is one of the most common cosmetic dental concerns that brings patients to search online for answers, and understandably so.

A grey or discoloured tooth can occur for a number of reasons, from previous dental trauma to root canal treatment. Unlike the general yellowing that affects the outer surfaces of teeth, this type of discolouration originates from within the tooth structure itself. These are known as internal stains, and they typically do not respond to standard external whitening treatments in the same way surface stains do.

Understanding why a tooth changes colour — and what options may be available — can help you feel more informed and confident when speaking with a dental professional. This article explains the causes of internal tooth discolouration, explores approaches such as internal tooth whitening, and outlines when it may be appropriate to seek a professional dental assessment. Whether your concern is recent or long-standing, knowing the facts is an important first step.

What Causes a Grey or Dead Tooth?

What is internal tooth whitening, and can it help a grey or dead tooth?

Why Do Teeth Turn Grey? Understanding Internal Discolouration

A tooth may turn grey or dark for several reasons, and the discolouration almost always relates to changes occurring inside the tooth rather than on its surface. The most common causes include:

• Dental trauma: A knock or blow to a tooth — even one that happened years ago — can damage the blood vessels and nerve tissue inside the pulp chamber. As these tissues break down, they release byproducts that gradually stain the inner layers of the tooth, producing a grey, brown, or dark appearance.
• Root canal treatment: After a root canal procedure, the tooth no longer has a living nerve supply. Over time, the remaining tooth structure can darken. Residual pulp tissue or materials used during treatment may also contribute to discolouration.
• Internal resorption: In some cases, the body may begin to break down tooth structure from within, a process that can cause pink or grey discolouration.
• Certain medications: Tetracycline antibiotics taken during tooth development (usually in childhood) can cause characteristic banding or grey-brown discolouration that is embedded within the enamel and dentine.

Discolouration can also present as white spots rather than grey — if that describes your concern, our guide on whitening teeth with fluorosis may be more relevant.

Understanding the underlying cause is essential because it determines which treatment approaches may be appropriate. A dental professional can assess the tooth clinically and with radiographs to identify the source of discolouration.

How Internal Stains Differ from External Stains

It is helpful to understand the distinction between external and internal tooth stains, as this directly affects which whitening methods may be effective.

External stains (also called extrinsic stains) sit on the outer surface of the enamel. They are commonly caused by tea, coffee, red wine, tobacco, and certain foods. These stains typically respond well to professional teeth whitening treatments because the bleaching agents can act directly on the discoloured enamel surface.

Internal stains (intrinsic stains), by contrast, originate from within the dentine or pulp chamber of the tooth. Because they are beneath the enamel layer, conventional external whitening gels cannot penetrate deeply enough to address them effectively. This is why a single grey tooth often remains unchanged even after a patient undergoes a full course of external whitening.

The key clinical difference is location. A tooth that appears grey due to internal changes requires a targeted approach — one that places the whitening agent inside the tooth itself. This is the principle behind internal bleaching, which a dentist can perform on teeth that have previously undergone root canal treatment. Without this distinction, patients may feel frustrated when standard whitening does not improve the appearance of a discoloured tooth.

The Science Behind a Dead Tooth: What Happens Inside

To understand why a tooth changes colour after trauma or nerve damage, it helps to know a little about tooth anatomy.

Each tooth contains an outer layer of enamel, which is the hard, translucent shell you see when you smile. Beneath the enamel lies dentine, a yellowish tissue that gives teeth much of their natural colour. At the centre of the tooth is the pulp chamber, which houses the nerve, blood vessels, and connective tissue that keep the tooth alive.

When the pulp is damaged — through a blow to the mouth, a crack, or severe decay — the blood supply to the tooth may be disrupted. As the pulp tissue deteriorates, haemoglobin and other breakdown products from red blood cells seep into the surrounding dentine. These compounds undergo chemical changes over time, producing dark pigments that become embedded within the tooth structure.

Because dentine is porous, these pigments can spread throughout the inner layers of the tooth. The enamel, being translucent, allows the darkened dentine to show through, giving the tooth its characteristic grey or brownish appearance. This process can take weeks, months, or even years to become noticeable, which is why some patients do not connect the discolouration to an injury that occurred long ago.

Internal Tooth Whitening: How the Procedure Works

Internal tooth whitening — sometimes referred to as internal bleaching or the walking bleach technique — is a well-established dental procedure designed to lighten a tooth that has darkened from within. It is typically performed on teeth that have already had root canal treatment.

The general process

1. Assessment: The dentist examines the tooth clinically and takes radiographs to confirm that the root canal treatment is sound and that the tooth and surrounding bone are healthy.
2. Preparation: A small access cavity is created in the back of the tooth (or an existing one is reopened). A protective barrier is placed over the root canal filling to seal it from the bleaching agent.
3. Placement of bleaching agent: A whitening material — commonly sodium perborate mixed with water or a hydrogen peroxide solution — is placed inside the pulp chamber.
4. Temporary seal: The access cavity is sealed with a temporary filling, and the bleaching agent is left in place for several days to a week.
5. Review and repeat: At a follow-up appointment, the dentist assesses the degree of lightening. The process may be repeated over two to four sessions until a satisfactory shade is achieved.
6. Final restoration: Once the desired result is reached, the tooth is permanently restored with a tooth-coloured filling.

The procedure is generally painless, as the tooth no longer has a living nerve. Results can be impressive, although the degree of improvement varies depending on the cause and severity of the discolouration.

Other Treatment Options for a Discoloured Tooth

While internal whitening is often the most conservative first approach for a root-treated grey tooth, it is not the only option available. Depending on the clinical situation, a dentist may discuss alternative or complementary treatments:

• Dental veneers: A thin porcelain or composite shell bonded to the front surface of the tooth can effectively mask discolouration. Porcelain veneers offer a durable and natural-looking result, although they require some preparation of the tooth surface. You may wish to learn more about cosmetic dental options that could be suitable.
• Dental crowns: If the tooth is significantly weakened or has extensive existing restorations, a crown may provide both aesthetic improvement and structural reinforcement.
• Composite bonding: A tooth-coloured composite resin can be applied to the front of the tooth to improve its appearance. This is a less invasive option, though it may not be as long-lasting as a veneer or crown.
• Combination approach: In some cases, a dentist may recommend internal whitening first to lighten the underlying tooth, followed by a veneer or bonding to achieve the best cosmetic result.

The most appropriate option depends on the individual tooth, the extent of discolouration, the structural integrity of the tooth, and the patient’s preferences. A thorough clinical assessment is always the starting point.

When to Seek a Professional Dental Assessment

If you have noticed a change in the colour of one or more teeth, it is sensible to arrange a dental evaluation. While discolouration alone is not always a sign of an active problem, there are certain situations where timely assessment is particularly important:

• A tooth that has recently changed colour following a knock, fall, or impact to the mouth
• Pain, tenderness, or sensitivity around a discoloured tooth
• Swelling of the gum near the affected tooth
• A persistent bad taste or the appearance of a small swelling (often called a gum boil) near the tooth root
• A previously root-treated tooth that has gradually darkened over time
• Discolouration in a child’s tooth following an injury

These signs may indicate that the tooth requires further investigation, such as vitality testing or radiographic examination, to determine whether treatment is needed. In many cases, early assessment provides more options and can help avoid more complex treatment later.

It is worth remembering that not every grey tooth requires urgent attention, but a professional opinion can offer reassurance and clarity about what, if anything, may be recommended.

Prevention and Maintaining Oral Health

While some causes of internal tooth discolouration — such as childhood medication exposure or genetic factors — cannot easily be prevented, there are practical steps that may reduce the risk of trauma-related discolouration and support overall oral health:

• Wear a mouthguard during sport: Custom-fitted mouthguards offer effective protection against dental trauma during contact sports and physical activities. This is one of the simplest ways to reduce the risk of damage to the teeth and supporting structures.
• Attend regular dental appointments: Routine check-ups allow your dentist to monitor the health of your teeth, including any that may have been previously injured or treated. Early detection of changes can make a significant difference in treatment outcomes.
• Maintain good oral hygiene: Brushing twice daily with fluoride toothpaste and cleaning between your teeth helps protect against decay, which can contribute to pulp damage and subsequent discolouration.
• Seek prompt advice after dental injuries: If you experience a blow to the mouth, even if there is no immediate pain, it is advisable to have the affected teeth assessed. Some injuries may not cause symptoms straight away but can lead to problems over time.
• Discuss whitening options with your dentist: If you are considering any form of teeth whitening in London, professional guidance ensures the approach is appropriate for your specific situation and that your teeth and gums are healthy before treatment begins. Learn more about whitening costs or book a consultation.
• Maintain regular dental hygiene appointments: Professional cleaning supports overall oral health and can help manage surface staining that may develop over time.

Key Points to Remember

• A grey or dark tooth is usually caused by internal changes, often related to trauma or root canal treatment.
• Internal stains do not respond to standard external whitening products.
• Internal tooth whitening is a well-established procedure that places a bleaching agent inside a root-treated tooth to lighten discolouration from within.
• Other options, including veneers, crowns, and composite bonding, may also be appropriate depending on the clinical situation.
• Treatment suitability always depends on an individual clinical assessment.
• Wearing a mouthguard during sport and attending regular dental check-ups can help reduce the risk of dental trauma and its consequences.

Frequently Asked Questions

A grey or darkened tooth can be a source of real concern, but it is important to know that effective treatment options are available. Internal tooth discolouration — whether caused by trauma, root canal treatment, or other factors — differs fundamentally from everyday surface staining, which is why it requires a different approach.

Internal tooth whitening offers a conservative and well-established method for lightening a discoloured root-treated tooth, and alternative options such as veneers, crowns, or bonding may also be appropriate depending on the clinical picture. The most important first step is always a professional assessment to understand the cause of the discolouration and determine which treatment, if any, is suitable.

Maintaining good oral health habits, wearing protective mouthguards during sport, and attending regular dental appointments all contribute to long-term dental wellbeing and can help reduce the risk of the kind of damage that leads to internal staining.

If you have noticed a change in the colour of a tooth, or if you have any concerns about your dental health, seeking professional advice is always worthwhile.

Disclaimer: This article provides general information only and does not constitute personalised medical or dental advice. Dental symptoms and treatment options should always be assessed individually during a clinical examination.