Dental abscess

What a dental abscess is

A dental abscess is a collection of pus caused by a bacterial infection, at the tip of a root, in the gum or in the bone that holds the teeth. The two most common kinds are:

• a periapical abscess, at the tip of the root. Bacteria reach the pulp, the soft tissue with nerves and blood vessels inside the tooth, through decay, a crack or an injury. The pulp dies, and the infection spreads out through the end of the root into the bone;
• a periodontal abscess, in the gum beside the root. It usually starts in a deep pocket between the tooth and the gum, where gum disease has let bacteria collect.

An infection around a partly erupted wisdom tooth can cause a similar swelling at the back of the jaw. A weakened immune system, for example with diabetes or during chemotherapy, makes abscesses more likely.

Symptoms

• an intense, throbbing pain in a tooth or the gum, which may start suddenly and get worse;
• pain that spreads to the ear, jaw or neck on the same side, often worse when lying down;
• a tooth that is tender to bite on, loose or discoloured;
• red, swollen gum, sometimes with a small spot that discharges pus, and a bad taste or bad breath;
• swelling of the face or jaw, swollen glands in the neck, a high temperature and feeling unwell.

An abscess is not always painful. Some are found only on an X-ray, as a dark area at the tip of a root. If the pus drains through the gum by itself the pain may ease, but the infection remains and still needs a dentist.

When it is urgent

A suspected abscess needs a dentist soon. Call 998 for an ambulance, or go to a hospital emergency department, if there is:

• difficulty breathing, speaking or swallowing;
• swelling around the eye, a painful eye or any change in eyesight;
• a lot of swelling inside the mouth, or difficulty opening it;
• swelling of the face, jaw or neck that is spreading, especially with a high temperature.

These signs can mean the infection is spreading beyond the tooth, and this is treated in hospital. Ask someone to take you rather than driving yourself. The guide to dental emergencies covers other urgent situations.

Why antibiotics alone are not enough

Antibiotics can slow bacteria spreading through the tissues, but they do not drain pus that has already collected, and they cannot reach bacteria inside a tooth whose pulp has died, because dead pulp has no blood supply to carry them there. Without drainage and treatment of the cause, the infection tends to return once the course ends.

For this reason, dental guidelines advise against antibiotics for most abscesses confined to the tooth and gum, and recommend dental treatment, with painkillers if needed. Antibiotics are added when the infection is spreading, when there is a fever or the person feels unwell, for people at higher risk of complications, and sometimes when drainage cannot be done straight away.

How an abscess is drained

1. Assessment. An examination, tests on the teeth and usually an X-ray show the source of the infection and the kind of abscess.

2. Anaesthetic. A local anaesthetic numbs the area, although pressure may still be felt.

3. Drainage through the tooth. For an abscess at a root tip, a small opening is made through the top of the tooth into the pulp chamber, and the pus drains out through the root canals. This is also where root canal treatment begins.

4. Drainage through the gum. Where pus has collected in a swelling of the gum, a small cut is made to let it out. On its own this is only a temporary measure.

5. Removing the tooth. If the tooth cannot be saved, taking it out lets the pus drain through the socket and removes the source of the infection at the same time.

For a periodontal abscess, the pocket between the tooth and the gum is also cleaned out. Painkillers and, in some cases, antibiotics may be advised afterwards.

Treating the cause

Drainage relieves the pressure, but the source of the infection still has to be treated. For a tooth whose pulp has died, the choice is usually between root canal treatment and removing the tooth. Root canal treatment cleans and seals the canals so that the tooth can be kept, and a filling or a crown then restores it. A tooth too broken down to restore, or one where root canal treatment is not possible, is removed.

A periodontal abscess needs treatment of the gum disease behind it: thorough cleaning below the gum line and good daily cleaning at home. If infection returns at the tip of a tooth that has already had root canal treatment, re-treatment or an apicectomy may be considered.

What helps until you are seen

• ibuprofen or paracetamol, taken as directed on the pack and never above the recommended dose. Ibuprofen is generally preferred for a dental abscess by those who can take it, and children under 16 should not take aspirin;
• cool, soft food, eaten on the other side of the mouth;
• avoiding food and drink that is very hot or very cold;
• a soft toothbrush, to keep the area clean.

These measures ease the symptoms for a while. They do not treat the abscess, and they should not put off a visit to the dentist.

Preventing abscesses

Abscesses usually start with decay or gum disease, so the same habits protect against both: brushing twice a day with a fluoride toothpaste and spitting rather than rinsing, cleaning between the teeth every day, cutting down on sugary food and drink, not smoking, and regular check-ups so that tooth decay and gum problems are found early. A knocked, chipped or cracked tooth is worth having checked, because an injury can let bacteria reach the pulp.