If the gum at the very back of your mouth is swollen, sore, and tastes bad, and you have a wisdom tooth that is half through, you likely have pericoronitis. It is an infection of the flap of gum sitting over a partly erupted wisdom tooth, and it is common, affecting roughly 5 percent of people, with about 95 percent of cases involving a lower wisdom tooth. It is most common between the ages of 21 and 25, when wisdom teeth tend to erupt. The good news is that mild cases often settle with simple care, while more severe ones respond well to prompt treatment.
Key takeaways
- Pericoronitis is inflammation and infection of the gum flap over a partly erupted wisdom tooth.
- It is most common in people aged 21 to 25 and usually affects a lower wisdom tooth.
- Food and bacteria get trapped under the gum flap, which is hard to clean, and infection follows.
- Mild cases often ease with warm salt rinses and good cleaning, but spreading swelling or fever needs urgent care.
- For recurring cases, removing the wisdom tooth is the most reliable long-term fix.
Why it happens
When a wisdom tooth only partly comes through, a flap of gum, called an operculum, often remains over part of it. The space under that flap is almost impossible to clean with a toothbrush. Food debris and bacteria collect there, and because the area stays moist and undisturbed, infection takes hold. This is why pericoronitis is really a problem of position and shape, not poor hygiene alone. A tooth that cannot fully erupt creates a trap that keeps causing trouble. Our wisdom teeth removal guide explains why these teeth so often cause problems.
The signs to recognise
Pericoronitis ranges from mild to severe. Common signs include a red, swollen, tender gum at the back of the mouth, pain that can radiate to the ear or jaw, a bad taste or smell from pus, difficulty opening the mouth fully, and discomfort when biting because the upper tooth presses on the swollen flap. In more serious cases there can be facial swelling, fever, and swollen glands in the neck, which signal that the infection is spreading.
What you can do tonight
For a mild flare, simple measures often bring relief while you arrange to see a dentist.
- Rinse with warm salt water several times a day, especially after meals, to flush debris from under the flap. A teaspoon of salt in a cup of warm water works well.
- Keep the area as clean as you gently can. A soft brush and careful cleaning around the tooth help.
- Use over-the-counter pain relief such as paracetamol or ibuprofen as directed on the packet, if suitable for you.
- A chlorhexidine or antiseptic mouthwash from the pharmacy can help reduce bacteria around the flap.
- Eat soft foods and avoid biting directly on the sore side.
These steps manage symptoms but do not remove the underlying cause, so a dental review is still important.
When it is an emergency
Most pericoronitis is uncomfortable rather than dangerous, but certain signs mean you should seek care urgently. Spreading facial swelling, swelling that affects the floor of the mouth or the throat, difficulty swallowing or breathing, a fever, or feeling generally unwell all suggest the infection is spreading and need prompt attention. Difficulty opening your mouth is also a red flag. If swallowing or breathing is affected, treat it as an emergency. Our dental emergency guide explains when to act fast, and a spreading infection can become a dental abscess.
How a dentist treats it
Treatment follows the severity. The evidence supports local treatment first, meaning the dentist cleans and irrigates under the gum flap to flush out debris and bacteria. This often brings rapid relief. Antibiotics are not the default. They are reserved for cases where the infection is spreading, there is fever, or the person is generally unwell, because overusing antibiotics for simple pericoronitis is unnecessary and contributes to resistance.
For the longer term, the key decision is what to do about the tooth. If the wisdom tooth is unlikely to erupt fully and pericoronitis keeps coming back, removing the tooth is widely regarded as the most reliable solution, because it eliminates the gum flap and the trap underneath. Occasionally, if the upper wisdom tooth is biting into the flap, removing the upper tooth or trimming the flap can help. Recovery after removal is covered in our extraction recovery timeline.
General cost in Australia
Fees depend on whether you need a simple clean-out, a flap removal, or full extraction, and how complex the tooth is. The figures below are general Australian market ranges, not a quote, and we do not list our own prices here.
| Treatment | Typical Australian range |
|---|---|
| Emergency consult and irrigation | $90 to $250 |
| Simple wisdom tooth extraction | $230 to $400 per tooth |
| Surgical extraction of an impacted wisdom tooth | $350 to $700+ per tooth |
If you have a sore wisdom tooth, the team at Lumi Dental can assess it, settle the infection, and explain whether removal is the right move. See our current deals page to book.
Frequently asked questions
Will pericoronitis go away on its own?
A mild flare can settle with salt rinses and good cleaning, but it often comes back while the gum flap remains. Treating the cause is what stops the cycle.
Do I need antibiotics?
Not usually. Cleaning under the flap is the first-line treatment. Antibiotics are reserved for spreading infection, fever, or feeling unwell.
Does the wisdom tooth always need to come out?
No. If the tooth is likely to erupt fully and the problem is a one-off, it may be managed without removal. Recurring infection usually points to extraction.
Why does it hurt to open my mouth?
Swelling and inflammation near the jaw muscles can make opening painful. Difficulty opening can also be a sign of a more serious infection, so have it checked.
Can I prevent it?
Keeping the area very clean helps, but if a wisdom tooth is partly erupted the trap remains. Regular reviews let your dentist decide whether to act before it flares repeatedly.
The takeaway
Pericoronitis is a common and painful infection around a part-erupted wisdom tooth. Mild cases often ease with salt rinses and careful cleaning, but spreading swelling, fever, or trouble swallowing means you should seek care urgently. Cleaning under the flap is the first treatment, and for recurring cases, removing the tooth is the most reliable fix. If a wisdom tooth is giving you grief, the team at Lumi Dental can help. Visit our current deals page to book.
