Pericoronitis: How Long a Flare-Up Lasts and What Settles It

Written by Dr. Nick Jadidi — Last updated November 13, 2026 · 8-minute read

This article is general information for our patients, not a diagnosis. If something in your mouth hurts, changes, or worries you, have it examined.

A deep, swollen ache at the very back of the lower jaw, in your late teens or twenties, is usually a wisdom tooth still only partway through. The flap of gum that half-covers it (the operculum) traps food and bacteria in a pocket no brush can reach. When that gum becomes infected, the result is pericoronitis.

That ache can also be a cavity, a cracked tooth, or a pocket of infection (an abscess) nearby, and they aren’t treated the same way. Telling them apart takes your history, an exam, tests and an X-ray. Use what follows to gauge how urgent your pain is.

Why a half-erupted tooth flares up

Wisdom teeth (third molars) are the last to arrive, and many only push partway through. Roughly 7 in 10 young adults have at least one that is stuck in the jaw or only partly through the gum. Food, plaque and bacteria slide under the gum flap and multiply, and the gum over the crown turns red, swollen and tender.

In published studies, a cold or similar infection came just before 43% of flare-ups, and a run-down week, exam stress or poor sleep can tip a quiet wisdom tooth the same way. It’s most common between about 20 and 30, and far more often in the lower jaw than the upper.

What a flare-up tends to feel like

A flare often starts as a deep ache at the back corner of the jaw, with pain on biting. As it builds, the clues include:

• A throbbing ache behind your last tooth, sometimes spreading to the ear or throat.
• A swollen gum flap that your upper teeth may bite onto and irritate further.
• A bad taste or smell, and sometimes a little pus from under the flap.
• A stiff jaw that won’t open fully (trismus).
• Tender lumps under the jaw (swollen glands), and occasionally a mild fever.

A mild grumble that settles in a day or two is the gentler end. If you have trouble swallowing or breathing, or swelling spreading toward your neck or eye, go to the hospital ER first.

Is pericoronitis dangerous?

Usually not — most flare-ups stay in the gum flap and settle once it is cleaned out, but the few that spread toward the neck or the floor of the mouth are serious and belong in a hospital, not a dental chair. What marks out the rare, spreading kind is not more pain but trouble with breathing and swallowing.

Use the signs, not the soreness, to decide where to go. A flare that is settling with rinses and is no worse the next day can wait for a normal appointment. A fever, or a jaw that will not open properly, means the infection is taking hold: call us at 705-721-9229 and we will make room. Trouble swallowing or breathing, a swelling spreading toward your neck or under your tongue, or a voice that has gone muffled means the hospital emergency department first, not us.

Settling a flare-up

The first visit is about calming things down, not rushing to surgery on an infected jaw. I gently clean and flush under the gum flap, and check the pain really is the wisdom tooth. At home, what helps:

• Warm salt-water rinses: a teaspoon of salt in a cup of warm water, several times a day, especially after meals, to keep the area flushed.
• An antibacterial mouthwash (chlorhexidine), if I recommend one, used as directed while the gum settles.
• Over-the-counter painkillers can take the edge off. Some aren’t right with asthma, a stomach ulcer or blood thinners, so ask your pharmacist what’s safe for you.

Antibiotics aren’t automatic. For a flare confined to the gum flap, a thorough clean and good home care usually do the job. I reserve antibiotics for when the infection is clearly spreading: facial swelling, fever, a jaw that will hardly open, swollen glands. At that point treat it as urgent and call our emergency dentist in Barrie rather than wait for a routine visit.

How long does the gum flap over a wisdom tooth stay sore?

A pericoronitis flare-up usually settles in three to seven days once the trapped debris is cleaned out and the area is kept clean. Left alone it often quietens in a week or two, then returns, because the gum flap is still there.

Does the tooth need to come out?

Often, no: a healthy wisdom tooth that has come through fully, that you can clean, and that causes no trouble can stay. Routine “just in case” removal was dropped after the UK’s guidance body (NICE) recommended against it, and the American Association of Oral and Maxillofacial Surgeons takes a similar line. The trade-off is monitoring at check-ups, because things change: after routine removal stopped in the UK, decay on the hidden back surface of the neighbouring tooth (the second molar) rose from about 5% to 19% of patients needing wisdom-tooth surgery.

I lean toward removal when the tooth is causing trouble or is very likely to:

• Repeated pericoronitis. One mild episode is often just watched, but two or more genuine flare-ups are among the best-supported reasons to remove a lower wisdom tooth, because each flare tends to invite the next.
• Decay that can’t be sensibly repaired, in the wisdom tooth or the one in front. A forward-tilted wisdom tooth traps plaque against its neighbour. Caught early, that neighbour can often be saved with a filling or, if the decay runs deep, root canal treatment; left too long, it may have to come out too.
• Infection that has spread, or a fluid-filled sac (a cyst) forming around a tooth stuck in the bone.
• Damage to the neighbour, such as the wisdom tooth slowly eating into its root.

A tooth blocked from coming through is impacted, and one leaning forward into its neighbour is the likeliest troublemaker. Angle, root shape and nerve proximity only show on an X-ray. I’ve written separately about what a tooth extraction actually involves.

If it does come out, when?

Removal tends to be most straightforward from the late teens to the mid-twenties, when the roots aren’t fully formed and the bone is more forgiving. Shorter roots sit further from the big nerve in the lower jaw, and younger bone recovers faster. Plenty of teeth are still removed comfortably later when there’s a reason to.

Youth alone is no reason to remove healthy, symptom-free wisdom teeth. If a tooth needs to come out, sooner is generally gentler than later.

On cost — I can’t quote a fee here, because it tracks the difficulty: the tooth’s angle, depth, root shape, and how close it sits to the nerve. An upper tooth that’s fully through and a lower one buried in bone are very different jobs, and we go through yours at the assessment. For eligible patients, the Canadian Dental Care Plan may cover part of it, and we offer direct billing so you’re not left chasing the paperwork.

Comfort, and the one risk I always explain

Removal is done with the area fully numbed (local anaesthetic): you feel pressure and movement, but not pain. For many wisdom teeth, uppers and straightforward lowers, the freezing alone is enough and you can drive yourself home. If you are anxious, tell us before we start: we work at your pace, explain each step, and stop whenever you raise a hand.

A small number of wisdom teeth are involved enough that removing them is a job for an oral surgeon in a hospital or surgical setting. If yours is one of them, I will say so at the assessment and arrange the referral.

One risk is specific to lower wisdom teeth: the nerve that gives feeling to the lower lip and chin runs close to the roots of some. When an X-ray suggests they’re tight, we may take a 3D scan (a CBCT) and consider removing only the crown, leaving the deepest roots in place to protect the nerve (a coronectomy). Temporary numbness follows roughly 1 in 20 (5%) surgical lower wisdom-tooth removals; permanent numbness is closer to 1 in 500, both rising the closer the roots sit to the nerve. I go through it before we proceed.

What recovery looks like

Swelling and soreness peak around day two or three, then ease over the following week. For a surgical lower wisdom tooth:

• First 24 hours. A little oozing is normal; gentle pressure on the gauze controls it. Keep your head propped up, rest, and avoid rinsing, spitting hard, smoking or drinking through a straw, all of which can disturb the clot.
• Days two to three. A cold pack on the cheek helps; stick to soft, cool foods, and start gentle salt-water rinses the day after surgery.
• The following week. Swelling settles, your mouth opens more easily, and you return to normal foods. Stitches are often the dissolving kind, or we remove them at a short review.

Dry socket is when the clot breaks down too early and leaves bone exposed. It tends to show up two to four days out as a deep, throbbing ache, often spreading to the ear, that ordinary painkillers barely touch. Dry socket follows roughly 3% to 10% of extractions, is more common in the lower jaw, and smoking roughly triples the risk, which is why I ask you not to smoke for a couple of days. It isn’t dangerous: cleaning the socket and placing a soothing dressing usually brings fast relief. More on dry socket and how we manage it.

Call us promptly if bleeding won’t settle with steady pressure, pain worsens after day three instead of easing, a fever or spreading swelling appears, or numbness of the lip or chin is still there the morning after; the freezing itself should wear off within a few hours.

Is wisdom tooth removal covered by the plan?

It can be — taking out a wisdom tooth falls within the treatment the Canadian Dental Care Plan helps toward, though whether yours is covered depends on your eligibility and the plan year. Wisdom teeth are also the case where the plan most often wants the treatment approved before it starts, because a buried lower tooth is a very different job from an upper one that is fully through, and the plan looks at which it is. That approval is our job, not yours: call us at 705-721-9229 with your details, we will check what applies, submit it, and give you the position in writing before anything is booked. We accept the plan here in Barrie and bill it directly. For who qualifies and how the plan works overall, see the Canadian Dental Care Plan explained.

What to do next

If a wisdom tooth keeps flaring or aching, the next step is an assessment: an exam, usually an X-ray, and a plan to watch it or remove it. Plenty of wisdom teeth are fine left alone. This article is part of our Emergency Patient Information library. To arrange an examination at Prince William Way Dental in Barrie, call us at 705-721-9229 or visit our contact page. Emergency examinations can also be booked online.