A throbbing gum behind your last molar, a sour taste that brushing does not shift, and a wisdom tooth that has only half appeared: together these usually point to pericoronitis, an infection of the gum flap that partly covers the tooth. It can be very sore and it tends to come back. Most episodes settle once the area is cleaned properly, and only a small number spread far enough to need urgent help.
A gum flap that cannot be cleaned is the root cause
Wisdom teeth often run out of room as they come through. When one stops partway, a fold of gum (dentists call it an operculum) stays draped over part of the biting surface. Underneath that fold is a warm, damp pocket that a toothbrush cannot reach. Food and plaque collect there, bacteria multiply, and the gum becomes inflamed.
This is why people who brush well still get pericoronitis. The problem is the shape of the space, not effort. If the upper wisdom tooth bites down on the swollen flap, each bite bruises it further and the irritation keeps going. Our wisdom teeth removal guide covers why these teeth so often end up partly erupted.
Symptoms usually build from a sore gum to a stiff jaw
Early on you may only notice a red, puffy patch of gum at the back of the mouth that hurts when you chew. As it progresses, the pain can spread towards the ear or along the jaw, pus can leave a bad taste or smell, and the jaw muscles nearby may tighten so that opening wide becomes difficult. Lower wisdom teeth are affected far more often than upper ones.
Signs that mean you should be seen the same day
Book urgently if you have swelling that is spreading into the cheek or under the jaw, a fever, swollen glands in the neck, or you can barely open your mouth. These suggest the infection is moving beyond the gum flap. Difficulty swallowing or breathing, or swelling under the tongue or down the neck, is an emergency: go to a hospital emergency department or call 000.
Left alone, a spreading infection can form a dental abscess. Our dental emergency guide explains which problems can wait for a normal appointment and which cannot.
Easing a mild flare until your appointment
If there is no facial swelling and you feel well otherwise, a few measures usually help. Rinse with warm salt water (about a teaspoon of salt in a cup of warm water) several times a day, particularly after eating, to wash debris out from under the flap. Keep brushing the area gently with a soft brush rather than avoiding it. An antiseptic mouthwash from the pharmacy, such as one containing chlorhexidine, can reduce bacteria for a short period.
Paracetamol or ibuprofen, taken as the packet directs and if they are suitable for you, can take the edge off the pain. Chewing on the other side and choosing softer food for a few days also helps. None of this removes the gum flap, so plan a dental check even if things improve.
Cleaning under the flap comes before antibiotics
At the appointment, the dentist or OHT gently flushes and cleans beneath the gum flap to remove trapped food and bacteria. Relief often follows quickly. If the opposing tooth is biting into the swelling, this may also be addressed.
Antibiotics are not the standard first step. A 2021 review by Schmidt and colleagues in the International Journal of Environmental Research and Public Health found that evidence-based recommendations favour local treatment and reserve antibiotics for severe or spreading infection, yet dentists in many countries still prescribe them routinely. Using them only when they are needed helps limit antibiotic resistance.
Removal is usually considered after repeat episodes
The longer-term question is whether to keep the tooth. If it is likely to come through fully, a single mild episode may be managed and monitored. If it is stuck at an angle or has no space, the flap will stay and infections tend to recur. The UK National Institute for Health and Care Excellence (NICE) advises that a first episode of pericoronitis, unless particularly severe, is not by itself a reason for surgery, while second or later episodes are an appropriate reason to consider removal.
Removing the tooth takes away the flap and the pocket under it. Our extraction recovery timeline describes what the days after surgery are usually like.
What treatment tends to cost
Costs depend on the treatment needed (a clean and review only, or an extraction) and on how the tooth sits in the jaw. As a typical market range in Sydney, and not Lumi's fees, a simple extraction is often $200 to $350 and a surgical extraction $400 to $900 per tooth. Your dentist can give you an itemised estimate after an examination and X-ray.
Common questions
Will it clear up without treatment?
A mild flare can calm down with salt rinses and careful cleaning, but it often returns while the flap is still there. Persistent or worsening symptoms need a dental review.
Is pericoronitis contagious?
No. It comes from bacteria that already live in the mouth becoming trapped under the gum flap.
Can I go to work or exercise with it?
For a mild flare, usually yes. If you have a fever, spreading swelling or feel unwell, rest and get seen promptly.
If a wisdom tooth is giving you trouble, the general dentists at Lumi Dental can clean the area, take an X-ray if needed and talk you through whether removal makes sense. You can book through our current deals page.
