When a cheek, jaw or the area under the chin puffs up and a tooth has been grumbling beforehand, the two are almost always connected. Bacteria from a dead nerve or an infected gum pocket have escaped the confines of the tooth and bone and are now multiplying in the soft tissues of the face. The swelling you can see is the body’s inflammatory response to that spread. Most cases are caught at the stage of a tender, hot cheek and settle quickly once the tooth is drained and treated. A minority progress fast, tracking along the natural planes between muscles towards the eye or the throat, and at that point the problem has stopped being dental and become medical. This page explains how to tell the two apart, what to do in the next few hours, why a course of antibiotics on its own leaves the problem in place, and how our Wimpole Street dentists deal with the tooth that started it.
A cheek or jawline that has visibly enlarged over hours or a day
Pus and inflammatory fluid collecting in the soft tissue outside the bone.
Skin over the swelling that feels warm, tight or shiny
A sign of active infection close to the surface.
A tooth on that side that throbs, feels raised or is agony to touch
Points to the source; occasionally the tooth itself has gone quiet because the nerve is dead.
Swelling under the tongue or beneath the lower jaw
Infection from lower molars can track here and threaten the airway; treat as an emergency.
Difficulty opening the mouth fully
Muscle spasm from infection near the jaw joint or chewing muscles.
Fever, chills, racing pulse, or swelling reaching the eye
Systemic involvement or spread towards dangerous spaces; these need hospital care.
Deep decay, a crack or an old knock can kill the pulp inside a tooth. Bacteria then multiply in the empty root canal and leak out through the tip into the jaw. Once pressure builds, the infection perforates the thin outer plate of bone and inflates the cheek or lip. This is the origin of most facial swellings we see.
In someone with gum disease, a deep pocket beside a tooth can block and fill with pus. The swelling here tends to be lower and closer to the gum margin than a root-tip abscess, and the tooth is often loose rather than raised.
A partially through lower wisdom tooth harbours bacteria beneath its gum flap. Repeated pericoronitis can spill into the tissues of the cheek and towards the throat, producing swelling at the angle of the jaw and difficulty swallowing.
Occasionally the socket or the treated tooth becomes infected in the days after a procedure, particularly if a fragment remains or a canal was not fully cleaned. Swelling that increases rather than decreases from day three onwards warrants a call.
Blocked salivary glands, a skin infection, a cyst, a reaction to an insect bite and, rarely, a tumour can all swell the face. Part of the emergency assessment is confirming the tooth really is responsible before treating it.
These are holding measures, not a substitute for an examination. Use any pain relief exactly as directed on the pack and check with a pharmacist if you take other medicines.
The tooth is identified by tapping, temperature and pressure testing, then X-rayed to confirm the extent of infection in the bone. We check your temperature, how far you can open and whether the swelling has crossed into any spaces that concern us.
About this treatmentReleasing the pus, either through an opening in the tooth or a small incision in the gum, is what brings pressure and pain down within hours. Antibiotics are added when there is spreading swelling or fever, but drainage comes first.
About this treatmentOnce the acute phase settles, a tooth worth keeping has its canals cleaned, disinfected and sealed over one or two visits, then protected with a crown. Fees are indicative at £695 for a front tooth and £895 for a molar.
About this treatmentA tooth split through the root, hopelessly decayed or surrounded by too little bone is removed, which eliminates the reservoir of infection. Simple extraction is from £250; surgical removal is quoted up to £650.
About this treatmentFor a gum abscess, the pocket is flushed and debrided under local anaesthetic and the underlying gum disease is then treated so that the pocket does not refill.
About this treatmentWhere swelling involves the floor of the mouth, the eye or the neck, or you are systemically unwell, we arrange immediate transfer to a maxillofacial unit for intravenous antibiotics and drainage under general anaesthetic.
An emergency visit at Wimpole Street, including the examination, X-rays and drainage or a dressing, is expected to be around £95. Root canal treatment that follows is indicative at £695 or £895 depending on the tooth, and a crown to protect a treated back tooth is from £995.
Extraction begins at £250, with surgical removal of a difficult or wisdom tooth up to £650. Treatment of a periodontal abscess is quoted after the emergency visit, with a full gum programme from £850 where disease is widespread. Hospital care for spreading infection is provided by the NHS. We give you the options, fees and likely outcomes in writing before anything beyond the emergency drainage is started.
Figures are indicative prices for Wimpole Street and are confirmed in a written plan once a dentist has examined you. Fees match our South Kensington and St Paul's clinics.
Leave your details and we will be in touch when the Marylebone diary opens. If the problem cannot wait, the same clinicians are already seeing patients in South Kensington and at St Paul's.
Related conditions
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.
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.
