Dead nerve (periapical abscess)
Deep decay, a crack or an old injury kills the pulp inside the tooth. Bacteria multiply in the empty canal and infection collects around the root tip. The tooth feels raised and is exquisitely tender to bite on.
Wimpole Street opens 1 October 2026. For a dental emergency today, call South Kensington 020 7183 2362 (open 7 days) or St Paul's 020 7183 3709 (Mon–Fri).
South Kensington
Open seven days a week
St Paul's, City of London
Open Monday to Friday
Emergency dentistry · Wimpole Street, Marylebone
Dental abscess treatment: draining infection and saving the tooth
An abscess is a pocket of pus trapped in bone or gum beside a tooth, and the pressure it creates is why it hurts so relentlessly. It will not resolve by itself, and antibiotics alone only hold it back for a while. Effective treatment means letting the pus out and removing whatever caused it, whether that is a dead nerve or a deep gum pocket. Wimpole Street opens on 1 October 2026; until then, abscesses are treated by the same clinicians at South Kensington seven days a week and at St Paul’s on weekdays.
Before you are seen
Right now: what to do
- 01
Take a painkiller as directed on the pack. Paracetamol and ibuprofen can be alternated if a pharmacist confirms both are appropriate for you; do not exceed the stated doses even if the pain is severe.
- 02
Rinse gently with warm salt water several times a day. It will not drain the abscess but it keeps the gum around any discharge point clean.
- 03
Sleep propped up. The throbbing eases slightly when your head is above the level of your heart.
- 04
If the abscess bursts and you taste something foul, rinse thoroughly and spit. The pressure relief is temporary and the tooth still needs treating, but you can note the time for the dentist.
- 05
Avoid heat on the face. A warm compress feels soothing but encourages infection to spread outward; a cool cloth is safer.
- 06
Do not attempt to lance or squeeze a gum boil yourself, and never place aspirin against the gum.
Take any painkiller only as directed on the pack, never place aspirin against the gum, and ask a pharmacist if you already take other medicines.
Diagnosis
What's likely causing it
Gum pocket (periodontal abscess)
In advanced gum disease, a deep pocket between tooth and gum becomes blocked and infection builds up beside the root rather than at its tip. The tooth may be loose and the gum swollen and shiny.
Partly erupted wisdom tooth
A flap of gum over a wisdom tooth traps food and bacteria, producing a localised infection called pericoronitis that can progress to an abscess and cause difficulty opening.
Failed root canal
A root-treated tooth can become re-infected years later if a canal was missed or the seal has broken down. The presentation is the same as a fresh periapical abscess.
Fractured root
A crack in the root gives bacteria a standing route in, and infection keeps returning until the crack is dealt with, often by removing the tooth.
Trapped foreign body
A fish bone, popcorn husk or toothbrush bristle pushed under the gum can set up an abscess in a completely healthy mouth. Removing it usually resolves things quickly.
At the clinic
How the emergency visit runs
- Step 1
Assess spread
We check your temperature, how far the swelling extends, how wide you can open and whether the airway is at any risk before anything else.
- Step 2
Locate the source
Tapping, cold testing and a digital X-ray show which tooth is responsible and whether the infection sits at the root tip or in a gum pocket.
- Step 3
Numb and drain
Local anaesthetic is placed away from the inflamed area. Pus is released either through the tooth itself, through the gum pocket or via a small incision in the swelling.
- Step 4
Treat the cause
For a dead nerve, root canal is started and the tooth dressed. For a gum abscess, the pocket is cleaned. A tooth that cannot be saved may be removed the same visit.
- Step 5
Medication and review
Antibiotics are prescribed only where infection has spread or you are systemically unwell. You get a written plan and a review date.
Fees
Emergency fees
The first visit is about controlling the infection and settling the pain; the assessment and drainage fees cover that. Definitive treatment of the tooth is then quoted separately and can be scheduled once the swelling has gone down.
| Item | Fee |
|---|---|
Emergency assessment New-patient rate (usual fee £95). | £30 |
Digital X-ray Per image. | £20 |
Incision and drainage Releasing pus through the gum, with local anaesthetic. | from £185 |
Open and dress tooth Relieving pressure through the tooth before root canal. | from £95 |
Root canal treatment Front tooth from £695, premolar from £795, molar from £895. | £695–£895 |
Extraction Simple from £250; surgical from £650. | £250–£650 |
Prescription Antibiotics or stronger analgesia where clinically indicated. | private prescription |
Indicative prices for Wimpole Street, identical to our South Kensington and St Paul's clinics. Whatever is recommended is set out in writing, with the cost, before any treatment starts.
Once you are home
Afterwards
- Swelling normally starts to shrink within 24 to 48 hours of drainage. If it is still growing after that, or your temperature rises, contact us or, out of hours, NHS 111.
- Finish any antibiotic course completely. Stopping early because you feel better allows resistant bacteria to regroup.
- Keep rinsing with warm salt water after meals for a few days to keep the drainage site clean.
- Eat soft food on the other side and avoid alcohol while taking antibiotics, especially metronidazole.
- Attend the follow-up. The drained abscess will return within weeks unless the root canal or extraction is completed.
- Once the tooth is sorted, book a hygiene visit and examination so any other early infections are caught before they abscess.
FAQ
Questions patients ask
Antibiotics reduce the bacteria in the surrounding tissue but cannot reach the dead nerve inside the tooth, which is where the infection is fed from. The swelling will settle, then return, and each round of antibiotics adds to resistance. National guidance is clear that drainage or tooth treatment is the actual remedy.
Anaesthetic is placed a little away from the swelling, where the tissue is not acidic and it works reliably. Once numb, most patients describe a sense of relief as the pressure releases rather than pain.
Yes. A burst abscess has simply found a drainage route through the gum; the infected tooth or pocket is unchanged and the boil will refill. It is also a sign that infection has been there for some time.
Most are painful but contained. Occasionally infection spreads into the tissues of the neck or towards the eye, and that is a hospital emergency. The red-flag list on this page tells you when to call 999 instead of a dentist.
Frequently, yes. Root canal treatment removes the dead tissue and seals the canals, and success rates for a first-time treatment are high. Teeth with a split root or very little sound structure left are the exceptions.
South Kensington sees emergencies seven days a week on 020 7183 2362; St Paul’s in the City covers Monday to Friday on 020 7183 3709. Both clinics offer same-day emergency appointments where possible and use the same fee list published here.
Also on this site
Other emergencies we treat
Marylebone, W1
Emergency care at Wimpole Street from 1 October 2026
Register your interest and we will contact you as the Marylebone diary opens. Anything that hurts today should go to South Kensington or St Paul's, where the same clinicians keep emergency slots each day.
Opening 1 October 2026
Wimpole Street is not yet seeing patients. Until then, please book or call our South Kensington clinic on 020 7183 2362 or our St Paul's clinic on 020 7183 3709. Questions about the new clinic: wimpolestreet@md.co.uk.
Until we open
Need an appointment before 1 October 2026?
The same clinical team already works from two other Medical & Dental clinics. Book at either one now and, if you prefer, move your ongoing care to Wimpole Street once the doors open.
South Kensington
- 20 Old Brompton Road, London SW7 3DL
- Open seven days a week
- 020 7183 2362
St Paul's, City of London
- 5 Ave Maria Lane, London EC4M 7AQ
- Open Monday to Friday
- 020 7183 3709
