Dental abscess: signs and what to do

Reviewed by Dr. Samar Fadavi, DDS

Short answer: A dental abscess is a pocket of pus caused by a bacterial infection in or around a tooth. Signs include throbbing pain, swelling, a pimple on the gum, a bad taste and sometimes fever. Call a dentist the same day. An abscess does not heal on its own; it needs drainage and treatment of the cause, such as a root canal or extraction.

Why an abscess needs attention today

An abscess is the body’s attempt to wall off an infection. Pus collects in the bone at the tip of a root or in the gum beside a tooth, and the pressure causes pain. Sometimes the abscess drains through a small opening in the gum and the pain suddenly eases. That can feel like the problem has gone away, but the infection is still there, and it can flare again or spread to the jaw, the face and, rarely, the neck.

This guide explains the types of dental abscess, the signs to watch for, what you can do at home while you arrange care, what to avoid and how the dentist treats it. It is general information for patients in Scarborough, the Danforth and East Toronto, not a diagnosis. For broader first steps, see our guide on what to do first in a dental emergency.

Types of dental abscess

Periapical abscess (at the root tip)

This is the most common type. Bacteria enter the pulp, the soft centre of the tooth, through deep decay, a crack or a broken filling. The pulp becomes infected and dies, and the infection travels down the root canals into the bone at the tip of the root. Our guide on what happens during a root canal explains the inside of a tooth.

Periodontal abscess (in the gum and bone beside the tooth)

This type starts in a deep gum pocket, usually in someone with gum disease. Food or bacteria trapped deep in the pocket can cause a sudden painful swelling of the gum. The tooth itself may still be alive.

Gingival abscess (in the gum only)

A smaller abscess in the gum surface, often caused by something lodged under the gum, such as a popcorn hull, a seed or a toothbrush bristle.

Abscess around a wisdom tooth

A partly erupted wisdom tooth can trap food and bacteria under a flap of gum. The infection, called pericoronitis, can form an abscess with swelling, pain on opening and a bad taste. Our guide on wisdom teeth explains why this happens.

Signs and symptoms of a dental abscess

• Severe, throbbing toothache that may spread to the ear, jaw or neck.
• Pain when biting or touching the tooth.
• Sensitivity to hot or cold, or pain that lingers after a hot drink.
• Swelling of the gum, cheek, jaw or under the chin.
• A small pimple or bump on the gum, sometimes leaking salty or bad-tasting fluid.
• Bad breath or a bad taste that does not go away with brushing.
• A tooth that feels loose or slightly raised when you bite.
• Red, shiny, tender gums around one tooth.
• Fever, tiredness or swollen glands in the neck.

Some abscesses cause very little pain, especially if they drain through a small opening in the gum. They may only be found on an x-ray at a check-up. Even without pain, the infection still needs treatment.

Warning signs that need the hospital

Most dental abscesses are treated at the dental clinic. Go to a hospital emergency department or call 911 if you have:

• Trouble breathing or swallowing.
• Swelling spreading under the tongue, down the neck or up toward the eye.
• A high fever, chills or a fast heartbeat and you feel very unwell.
• Trouble opening your mouth or a stiff, painful neck.
• Confusion or drowsiness.

These signs can mean the infection is spreading into deeper spaces of the face and neck. That is rare, but it is serious and needs urgent medical care.

What causes a dental abscess

• Untreated cavities that reach the pulp.
• A cracked or broken tooth that lets bacteria in. Our guide on cracked tooth symptoms explains how cracks develop.
• An old filling or crown that has leaked at the edges.
• An injury to a tooth that damaged the nerve, even years earlier.
• Gum disease with deep pockets around the teeth.
• Food or debris trapped under the gum.
• A partly erupted wisdom tooth.

Who is more at risk

Anyone can develop an abscess, but the risk is higher with frequent sugary snacks or drinks, dry mouth, smoking, diabetes that is not well controlled, a weakened immune system and long gaps between check-ups. Older adults who take medicines that cause dry mouth are especially prone to decay along the gum line and around old fillings.

What to do today while you arrange care

1. Call the clinic. Explain your symptoms, when they started and whether you have swelling or fever. Same-day visits are available.
2. Rinse with warm salt water. Dissolve half a teaspoon of salt in a cup of warm water and rinse gently a few times a day. It can soothe the gum and help a draining abscess stay clean.
3. Use a cold compress outside the cheek. Ten to 15 minutes at a time can ease swelling and pain.
4. Take over-the-counter pain medicine as directed. Ask a pharmacist which product suits you, especially if you take other medicines, are pregnant or have health conditions.
5. Keep your head raised. Sleeping with an extra pillow can reduce throbbing.
6. Eat soft, lukewarm foods on the other side of the mouth, and drink plenty of water.
7. Keep brushing and flossing gently, including around the sore tooth, to keep bacteria down.

What to avoid with an abscess

• Do not squeeze, pop or poke a bump on the gum. It can push the infection deeper.
• Do not use heat packs on the face. Heat can draw the infection outward and increase swelling.
• Do not put aspirin or other tablets on the gum; they can burn the tissue.
• Do not take leftover antibiotics or someone else’s antibiotics. The wrong drug or dose can hide the problem and leave the infection behind.
• Do not wait because the pain has eased. Pain often fades when the abscess drains or the nerve dies, but the infection remains.
• Do not chew on the sore tooth or eat very hot, cold or sugary foods.
• Avoid smoking and alcohol, which slow healing.

How the dentist diagnoses an abscess

The dentist will ask about your symptoms and health, examine the tooth and gum, tap the tooth gently, check how it responds to cold and check for swelling and loose teeth. X-rays show changes in the bone at the root tip or beside the tooth. In some cases a 3D scan (CBCT) helps the dentist see the roots and the extent of infection more clearly. The clinic offers CBCT 3D imaging when it is needed.

How a dental abscess is treated

The aim is to remove the infection, relieve the pressure and treat the cause so it does not come back. Options include:

Draining the abscess

The dentist may make a small opening in the gum or through the tooth to let the pus drain. The relief from pressure is often immediate. The area is cleaned and rinsed with saline.

Root canal treatment

If the tooth can be saved, root canal treatment removes the infected pulp, cleans and disinfects the canals and seals them. Back teeth usually need a crown afterwards for protection. Our root canal treatment page explains this care at our clinic.

Extraction

If the tooth is too damaged to repair, it is removed and the abscess drains through the socket. A missing tooth can later be replaced with an implant, bridge or denture. Our tooth extraction page explains removal and aftercare.

Gum treatment

A periodontal abscess is drained and the deep pocket cleaned. Ongoing gum care helps prevent new abscesses.

Antibiotics

Antibiotics are used when infection is spreading, when there is fever or swelling, or for people with certain health conditions. They help control infection, but they do not replace drainage and treatment of the tooth. Take the full course exactly as prescribed.

Recovery after treatment

Most people feel much better within a day or two of drainage and treatment. The tooth and gum may be tender for several days. Follow the dentist’s instructions about rinsing, pain medicine and foods. If you were given antibiotics, finish the course. Call the clinic if swelling grows, fever returns or pain gets worse after it had improved.

Abscess and your general health

Dental infections can affect the rest of the body, and some health conditions make infections harder to fight. Tell the dentist if you have diabetes, heart conditions, an artificial joint, a weakened immune system or are pregnant, and bring a list of your medicines. Our guide on oral health and overall health explains these links in more detail.

How to prevent a dental abscess

• Brush twice a day with fluoride toothpaste and clean between your teeth every day.
• Limit sugary snacks and drinks, especially sipping through the day.
• Treat cavities while they are small, before they reach the nerve.
• Replace old or broken fillings and crowns when the dentist recommends it.
• Keep gum disease under control with regular cleanings.
• Wear a mouthguard for sports and a night guard if you grind.
• Keep regular check-ups and x-rays so silent infections are found early. Our family dentistry page explains routine visits.

Abscess myths to set aside

• “The swelling went down, so it is healed.” Swelling can shrink when pus drains through the gum, but the source of infection is still inside the tooth or pocket.
• “A tooth with a root canal cannot get infected.” It can. A leaking filling, a new crack or a missed canal can let bacteria back in.
• “Pulling the tooth is always simpler.” Removal is quicker on the day, but it leaves a gap that can shift neighbouring teeth and often needs replacing later. Keeping a healthy root is usually preferred when the tooth can be saved.
• “Clove oil or a home rinse will clear it.” Home measures can ease discomfort for a short time. They do not reach the infection at the root tip or deep in the gum.
• “Children do not get abscesses in baby teeth.” They do, and an infected baby tooth can affect the adult tooth forming underneath, so it needs care too.

Questions to ask at your visit

• What type of abscess is this, and what caused it?
• Can the tooth be saved, and what are the options if it cannot?
• Do I need antibiotics, and how should I take them?
• What should I watch for at home in the next few days?
• When should I come back for a follow-up or x-ray?

When to see a dentist

Call the clinic the same day if:

• You have a throbbing toothache or pain when biting.
• You notice swelling of the gum, cheek or jaw.
• You see a pimple or bump on the gum, with or without fluid.
• You have a bad taste or bad breath that will not go away, with tooth pain.
• You have a fever with tooth pain or swelling.

Go to the hospital if swelling spreads to the eye or neck or you have trouble breathing or swallowing. Our emergency dentist page explains same-day visits. You do not need to be an existing patient.

Questions about dental abscesses

Will an abscess go away on its own?

No. The pain may ease if it drains, but the infection stays until the cause is treated.

Can antibiotics alone treat an abscess?

Antibiotics can control spreading infection, but the tooth still needs drainage and treatment, such as a root canal or extraction.

Is a pimple on my gum an abscess?

Often, yes. A small bump that leaks fluid is usually a drainage path from an infection at the root. Book a visit to have it checked.

Can I go to work with a dental abscess?

Many people can, but call the dentist first and arrange treatment the same day. Stay home and seek care if you have fever or spreading swelling.

Can I get an abscess under a crown or root canal tooth?

Yes. A leaking crown, a new crack or bacteria left in a canal can cause infection. Retreatment or another procedure can often still save the tooth.

Is a dental abscess dangerous during pregnancy?

Infection should be treated during pregnancy. Tell the dentist you are pregnant so x-rays, freezing and medicines are planned with care. Our guide on pregnancy and oral health has more detail.

How long does it take to feel better after treatment?

Most people feel relief within a day or two. Tenderness can last several days.