What Is a Dental Abscess – Symptoms, Causes & Treatment Guide

A dental abscess is a collection of pus that forms inside or around a tooth as a result of bacterial infection. It is one of the most common reasons patients seek emergency dental care — and for good reason. Without treatment, the infection does not go away on its own.

Recognising dental abscess symptoms early gives you the best chance of straightforward, effective treatment. The pain can be intense, but in some cases an abscess develops quietly with little warning until swelling appears or a gum boil forms on the surface of the gum.

Understanding the tooth abscess causes, knowing what gum boil treatment involves, and learning when professional care is needed are all covered in this guide. If you are experiencing symptoms right now, Emergency Dentist London offers same-day assessment and treatment across the week.

What Is a Dental Abscess?

A dental abscess is a pocket of pus caused by a bacterial infection inside or around a tooth. It develops when bacteria enter the tooth through decay, cracks, or gum disease and multiply within the soft tissue or bone. There are two main types — a periapical abscess at the tip of the tooth root, and a periodontal abscess in the gum beside the root. Both require professional treatment to resolve safely.

The difference matters because it affects how the abscess is treated. A periapical abscess typically starts from deep decay or a dying nerve inside the tooth. A periodontal abscess usually results from gum disease trapping bacteria in a pocket beside the tooth.

Regardless of type, the message is the same. A dental abscess will not heal by itself. The infection needs to be addressed at its source. Ignoring the symptoms allows the infection to progress, making treatment more complex and recovery longer.

Dental Abscess Symptoms — What to Look For

Dental abscess symptoms can appear suddenly or build gradually over days. Some patients experience severe pain from the outset, while others notice swelling or a bad taste before the pain arrives. Here are the key signs to watch for:

• Throbbing, persistent pain in the tooth, jaw, or ear on the affected side — often worse at night or when lying down
• Swelling in the gum near the affected tooth, sometimes forming a visible lump or gum boil
• Facial swelling on the cheek or under the jaw
• A bad taste in the mouth — often described as salty or metallic — caused by pus draining from the abscess
• Sensitivity to hot and cold food and drinks
• Pain when biting or chewing
• A raised temperature or general feeling of being unwell
• Redness or tenderness in the gum tissue
• Difficulty opening the mouth fully

If you recognise several of these dental abscess symptoms, prompt assessment is the safest course of action. Our dental abscess treatment service provides same-day care.

Tooth Abscess Causes Explained

A tooth abscess forms when bacteria reach the inner structures of a tooth or the surrounding tissues. Several pathways can lead to this. Understanding the tooth abscess causes helps explain why treatment targets the source of infection, not just the symptoms.

Deep decay. This is the most common cause. When a cavity is left untreated, it grows deeper over time. Eventually, bacteria reach the pulp — the soft tissue inside the tooth containing nerves and blood vessels. Once inside, infection takes hold and spreads to the root tip, forming an abscess.

Cracked or fractured tooth. Even a tiny crack in the enamel can allow bacteria to enter the inner layers of the tooth. Cracks may result from biting hard food, trauma, or weakening caused by large fillings. Over time, bacteria travel along the fracture line and reach the nerve.

Untreated infection. A tooth with a history of pain or sensitivity that has never been properly assessed may have a low-grade infection that has been developing quietly. Without treatment, these infections can progress to a full abscess. Infected tooth root treatment is often needed to resolve the problem completely.

Trauma. A blow to the face or a fall that damages a tooth can kill the nerve, even if the tooth looks intact from the outside. A dead nerve provides an ideal environment for bacteria, and an abscess can form weeks, months, or even years after the original injury.

Failed restoration. Occasionally, a filling, crown, or previous root canal does not fully seal out bacteria. Micro-leakage beneath a restoration can allow infection to develop over time.

What Is a Gum Boil and Gum Boil Treatment?

A gum boil is a small, pus-filled swelling that appears on the surface of the gum. It is sometimes called a parulis or a fistula. It forms when a dental abscess creates a drainage channel through the bone and gum tissue, allowing pus to escape into the mouth.

Patients often notice a gum boil as a soft, whitish or reddish lump near the base of a tooth. It may burst on its own, releasing a foul-tasting liquid. When this happens, the pain often eases temporarily — which leads some people to believe the problem has resolved. It has not.

A gum boil is a sign that infection is still present beneath the surface. The pus has simply found an exit route. Without proper gum boil treatment, the underlying abscess remains active and the boil will return.

Why professional drainage is needed. Dental abscess drainage carried out by a dentist removes the infection at its source. This may involve opening the tooth to clean the infected root canals, or making a small incision in the gum to drain the abscess directly. Simply waiting for a gum boil to drain on its own does not treat the infection — it only provides temporary relief.

For more detailed information on this condition, visit our dental abscess condition page.

Do Antibiotics Cure a Dental Abscess?

This is one of the most commonly misunderstood aspects of dental infection. Antibiotics for dental abscess can help manage the infection, but they rarely solve the problem on their own.

Antibiotics work by fighting bacteria in the bloodstream and surrounding tissues. They can reduce swelling, slow the spread of infection, and bring down a raised temperature. In some cases, a dentist will prescribe antibiotics before carrying out definitive treatment — particularly if swelling is severe or the patient is unwell.

However, the source of infection — whether it is decayed tissue inside the tooth, a dead nerve, or trapped bacteria in a gum pocket — remains untouched by antibiotics. The pus and infected material need to be physically removed or drained. Without this step, the abscess will return once the antibiotic course finishes.

Think of it this way: antibiotics control the fire, but only dental treatment puts it out.

For a more detailed look at how antibiotics interact with dental infections, read our article on antibiotics and tooth infection.

Signs of Spreading Infection — When It Becomes Urgent

Most dental abscesses remain localised to the tooth and surrounding gum. With timely treatment, they are resolved without complication. However, certain signs of spreading infection indicate that the situation has become more serious and needs urgent attention.

Seek immediate care if you notice any of the following:

• Swelling that is increasing or spreading — particularly towards the eye, under the jaw, or down the neck
• Difficulty swallowing or breathing — even mild restriction should be treated as urgent
• A high temperature alongside dental pain and swelling
• Severe, unrelenting pain that does not respond to over-the-counter medication
• Feeling generally unwell — fatigue, chills, or nausea alongside dental symptoms
• Difficulty opening the mouth more than a centimetre or two

These signs of spreading infection mean the bacteria may be moving beyond the tooth and into surrounding tissue or deeper spaces in the head and neck. Prompt professional care is essential.

Our detailed guide on 5 warning signs a tooth infection is spreading explains each of these indicators in more depth.

How Is a Dental Abscess Diagnosed?

Diagnosing a dental abscess involves a straightforward clinical process. The sooner the cause is identified, the sooner effective treatment can begin.

Clinical examination. The dentist examines the affected tooth, the surrounding gum, and the nearby tissue. They look for swelling, redness, gum boils, and tenderness. Gently tapping on the tooth or applying pressure helps determine which tooth is involved and whether the infection has reached the root.

X-ray. A digital X-ray reveals what is happening beneath the surface. It shows the shape and length of the tooth root, the presence of an abscess at the root tip, bone loss caused by infection, and any deep decay that may have triggered the problem. This is an essential step in planning the right treatment.

Identifying the infected tooth root. In some cases, the source of infection is not immediately obvious — especially when multiple teeth have large restorations or when pain is radiating across several teeth. The X-ray, combined with clinical tests, helps pinpoint the exact tooth responsible.

At Emergency Dentist London, a mandatory assessment fee for diagnosis applies to all emergency appointments. This covers the clinical examination, any X-rays required, and a full explanation of your treatment options. The fee is clearly communicated before your visit, and there are no hidden charges. Full pricing details are available on our pricing page.

Treatment Options for Dental Abscess

Once the abscess has been diagnosed, treatment focuses on removing the source of infection and allowing the area to heal. The approach depends on the severity and location of the abscess.

Dental Abscess Drainage

If the abscess has formed a visible swelling or gum boil, the dentist may drain it during the appointment. This involves making a small, controlled incision to release the trapped pus. The area is numbed with local anaesthetic first, so the procedure itself should not be painful.

Drainage provides rapid relief from the intense pressure that causes so much of the pain. Once the pus is released, patients typically feel a significant improvement almost immediately. The area is then cleaned, and further treatment is planned to address the underlying cause.

Infected Tooth Root Treatment

When infection has reached the pulp and root of the tooth, root canal treatment is often the best option. This procedure removes the infected tissue from inside the tooth, cleans and disinfects the root canals, and seals them to prevent reinfection.

Root canal treatment saves the natural tooth and eliminates the infection at its source. It is the preferred approach whenever the tooth structure is strong enough to support a restoration afterwards.

If the tooth is too badly damaged to save — for example, if the root is fractured or if extensive bone loss has occurred — extraction may be recommended instead. The dentist will always explain both options clearly so you can make an informed decision.

Booking Urgent Care

If you suspect a dental abscess, early assessment gives you the widest range of treatment options and the smoothest recovery. Waiting for the pain to become unbearable or for swelling to spread makes treatment more complex and recovery longer.

At Emergency Dentist London, we offer same-day emergency dental appointments for patients with suspected abscess, infection, or significant dental pain. You do not need a referral or prior registration. Simply get in touch and we will arrange the earliest available slot.

Visit our booking page to reserve your appointment online, or call us directly. Our emergency dentists are experienced in diagnosing and treating dental abscesses efficiently, with a focus on your comfort throughout.

Frequently Asked Questions

What are the main dental abscess symptoms?

The most common dental abscess symptoms include a persistent, throbbing toothache that may radiate to the jaw or ear, swelling in the gum or face, a bad taste in the mouth, and sensitivity to hot or cold. Some patients also experience a raised temperature and general feelings of being unwell.

A visible gum boil — a small, pus-filled lump on the gum — is another telltale sign. Not all abscesses cause severe pain initially, so swelling or a gum boil may be the first noticeable symptom.

If you recognise these symptoms, seeking professional assessment promptly is the best course of action.

What causes a tooth abscess?

The most common tooth abscess causes are untreated dental decay, cracked teeth, and trauma. When bacteria penetrate the outer layers of the tooth and reach the soft tissue inside, infection develops and can spread to the root tip, forming an abscess.

Failed restorations, such as old fillings or crowns that have developed micro-leakage, can also allow bacteria to enter the tooth over time. Gum disease is another pathway, particularly for periodontal abscesses that form in the gum tissue beside the root.

In every case, the underlying cause is bacterial — which is why treatment must remove or drain the infected material rather than simply managing symptoms.

Does gum boil treatment cure infection?

Gum boil treatment addresses the visible symptom, but lasting resolution requires treating the source of infection beneath it. A gum boil forms because an abscess has created a drainage channel to the surface. Draining the boil or allowing it to burst provides temporary relief, but the infection inside the tooth or bone remains.

Effective gum boil treatment involves dental abscess drainage combined with root canal treatment or extraction of the affected tooth. This eliminates the bacterial source and prevents the boil from returning.

If you notice a gum boil, it is a clear indication that professional care is needed — even if the pain is mild or intermittent.

Do antibiotics for dental abscess work alone?

Antibiotics for dental abscess help control the infection, but they do not cure it on their own. They reduce bacterial activity in the surrounding tissues, which can decrease swelling and prevent the infection from spreading further. However, the infected material inside the tooth or gum pocket remains untouched.

Once the antibiotic course ends, the infection typically returns because its source has not been removed. Dental treatment — such as drainage, root canal, or extraction — is required to resolve the abscess permanently.

Your dentist may prescribe antibiotics as part of your overall treatment plan, particularly if swelling is significant, but they are a supporting measure rather than a standalone cure.

What are signs of spreading infection?

Signs of spreading infection include swelling that extends beyond the immediate area of the tooth — for example, spreading to the cheek, under the jaw, or towards the eye. A high temperature, difficulty swallowing, difficulty opening the mouth, and feeling generally unwell are also warning signs.

If you experience any of these symptoms alongside dental pain, it suggests the infection may be moving beyond the tooth and into deeper tissue. This situation requires urgent professional care without delay.

Most dental abscesses remain localised when treated promptly. The key is not to wait and hope it resolves on its own — because it will not.

Watch: Your Emergency Dental Appointment Explained