Pericoronitis: Swollen Gum Around a Wisdom Tooth

Pericoronitis is inflammation and infection of the gum around a tooth that has only partly come through, most often a lower wisdom tooth. A flap of gum can sit over part of the tooth, and food and bacteria can collect underneath it. The gum then becomes red, swollen and sore, and can be painful to bite on or to open your mouth around.

It often settles with good cleaning and a dentist's care, but it can come back, and sometimes it spreads. This post explains the symptoms and causes, what you can safely do at home and what to avoid, what a dentist does, when removing the tooth is discussed, and the signs that mean you should get help urgently. Only a dentist can say whether this is what is affecting you, because other problems can cause similar pain.

Key takeaways

• According to the NHS, infections of the gum around a wisdom tooth are known as pericoronitis, and they are one of the reasons wisdom teeth are removed.
• Typical signs are a swollen, painful gum at the back of the mouth and a bad taste.
• Gentle cleaning around the area, warm salt water rinses and over the counter pain relief used as directed are the usual home care. Pushing or cutting at the gum is not.
• Pain that lasts more than three or four days or gets worse should be seen by a dentist.
• Difficulty opening your mouth, spreading facial or neck swelling, fever, or trouble swallowing or breathing need urgent help.

What is pericoronitis?

Pericoronitis means inflammation around the crown of a tooth. In the British Journal of General Practice, Renton and Wilson describe it as inflammation and infection of the soft tissues around a partially erupted tooth. Guy's and St Thomas' NHS Foundation Trust calls it an infection of the gum around the tooth and says it is the most common reason why wisdom teeth are removed.

Wisdom teeth, or third molars, are the last to appear, usually in the late teens or twenties. Many have little room, so they may come through only partway, lean sideways, or stay below the gum. A tooth in that position is hard to clean, which is where the trouble starts.

Pericoronitis can be short lived, or it can return again and again. Dentists sometimes describe an acute episode, with pain and swelling, and a milder recurring type, with a dull ache, a bad taste and bad breath.

Symptoms of a swollen gum around a wisdom tooth

Guy's and St Thomas' says this type of infection can cause pain and swelling, but sometimes the symptoms are mild. Commonly described signs include:

• A red, swollen or shiny gum at the very back of the mouth.
• A bad taste or bad breath, sometimes with pus or fluid from under the gum.
• Difficulty opening your mouth fully, known as trismus.
• Pain when swallowing.
• Swollen glands under the jaw or in the neck.
• Fever or feeling generally unwell in more serious cases.

You may have only one or two of these. A mild ache that comes and goes can be the milder, recurring type. The warning signs are covered in the urgent help section below.

How it differs from other problems

A swollen gum at the back can also come from a decayed tooth, a dental abscess, gum disease or food caught between teeth. A dental abscess can look similar and may need quicker treatment, so a check is worth having rather than guessing. Pain and gum swelling are common with impacted wisdom teeth. Our post on tooth abscesses explains when swelling needs urgent care.

What causes pericoronitis?

The main cause is a wisdom tooth that is only partly through the gum. Cleveland Clinic explains that a gum flap, called an operculum, can trap food, bacteria and debris underneath, which leads to infection. Several things make that more likely:

• A partly erupted or impacted tooth. The less of the tooth is exposed, the harder it is to keep clean.
• Lower wisdom teeth. They are the ones most often affected.
• Extra gum tissue over the tooth. More flap means more space for debris.
• Age. Cleveland Clinic lists being in your twenties among the risk factors, as wisdom teeth are coming through.
• Poor cleaning at the back of the mouth. This is easy to do when the area is sore.
• Anything that lowers resistance to infection, such as feeling run down, stress or pregnancy. Cleveland Clinic also lists diabetes.

Having one of these does not mean you will get pericoronitis, and you can have it without any of them.

Safe home care while you wait for a dentist

Home care can ease symptoms for a short time. It does not replace a dental assessment, particularly if the problem is new, is not improving, or comes back. The advice below follows an NHS pharmacy dental fact sheet from Health Education England and the British Journal of General Practice article cited above.

What helps

• Keep the area clean. The NHS fact sheet suggests a small toothbrush or interdental brush. Brush gently around the gum, because skipping the area lets bacteria build up.
• Rinse with warm salt water. The same fact sheet advises warm salt rinses two to three times a day. Do not swallow the water.
• Use an antiseptic mouthwash if your dentist or pharmacist recommends one, following the label.
• Take over the counter pain relief as the packet directs. If you are unsure which is suitable for you, ask a pharmacist.
• Eat soft foods and chew on the other side, so the area is not knocked.

What to avoid

• Do not cut, pick or lift the gum flap with a pin, a fingernail or anything sharp. You can make the infection worse.
• Do not put a tablet against the gum. The British Journal of General Practice article says tablets should be swallowed, not placed beside the gum, because they can damage the tissue.
• Do not use leftover medicines, including antibiotics. They are a prescribing decision for a dentist or doctor, who will decide whether they are needed.
• Do not wait it out if it is getting worse. The British Journal of General Practice article advises seeing a dentist if pain persists for more than three or four days or intensifies.

If the swelling keeps growing, stop home treatment and get advice.

What a dentist does for pericoronitis

A dentist will look at the gum, ask about your symptoms and how long you have had them, check how widely you can open and whether the glands in your neck are swollen. Our emergency appointment is built around that kind of same day assessment.

Treatment for an acute episode

• Cleaning under the flap. The dentist gently cleans away trapped debris from under the gum flap.
• Advice on home cleaning, including how to reach the area with a small brush.
• Pain relief advice, suited to your health and any medicines you take.
• Antibiotics only if needed. The British Journal of General Practice article describes them as needed when there is trismus, or infection spreading with swollen glands and fever. For a localised problem, good cleaning is the first step. Your dentist decides.

Treatment if it keeps coming back

The British Journal of General Practice article says that for chronic recurrent pericoronitis the preferred treatment is early removal of the wisdom tooth, rather than repeated courses of painkillers or antibiotics. Antiseptic mouthwash alone is described as at best a temporary measure for recurring problems. Some dentists also discuss trimming away the gum flap, called an operculectomy, in selected cases. Whether that suits you depends on the tooth, so it is a decision for you and your dentist. If removal is planned, our post asks whether PRP is necessary for wisdom teeth removal.

Our guide to dental hygiene describes professional cleaning and gum care, and regular check ups help your dentist keep an eye on how a wisdom tooth is coming through.

When does a wisdom tooth need to come out?

Not every wisdom tooth with a swollen gum has to be removed. The NHS says that if a wisdom tooth is not causing problems, it will usually be left where it is and monitored at routine check ups. Removal is generally discussed when problems keep happening, such as repeated infections, pain, decay in the tooth or the one next to it, or gum disease.

Hull University Teaching Hospitals NHS Trust says the most common reason for removal is repeated infections of the gum over a wisdom tooth. The NHS also says problems from wisdom teeth can include infections of the gums, pain, swelling, decay, gum disease, cysts and abscesses.

What removal involves

The NHS says wisdom tooth removal is usually done with a local anaesthetic injection to numb the gum. Sedation is generally used when the teeth are harder to remove or you are anxious, and a general anaesthetic is another option for difficult cases. If you are nervous, dental sedation with IV sedation is available, and our oral surgery team carries out wisdom tooth removal. Tooth extraction can be regular or surgical.

Most people recover within a few days to a couple of weeks. The NHS says you can usually return to normal activities the day after, and that swelling and pain should start to improve after one or two days. A dentist can explain what to expect for your tooth.

When to see a dentist or seek urgent help

See a dentist promptly if the gum has been sore for more than three or four days, if it comes back repeatedly, or if you cannot clean the area because it hurts. Early assessment tends to mean simpler treatment.

Get urgent dental advice

Ask for an urgent dental appointment, or call NHS 111 for advice, if you have any of the following. The NHS pharmacy dental fact sheet lists limited mouth opening (less than two fingers' width), obvious facial or neck swelling, difficulty swallowing, and severe pain that painkillers do not control as signs for urgent attention. The British Journal of General Practice article adds that trismus, swollen glands, fever and difficulty swallowing mean the infection may be spreading.

Call 999 or go to A&E

The NHS advises calling 999 or going to A&E if you find it hard to breathe, speak or swallow, or have a lot of swelling in your mouth. Do not drive yourself. Ask someone to take you or call for an ambulance. Spreading swelling of the face or neck also needs urgent attention.

Our dentists see urgent dental problems, but breathing or swallowing difficulty is a medical emergency, so go to A&E first.

Preventing pericoronitis

You cannot always prevent it, because it depends on how the tooth comes through, but these steps help.

• Clean carefully around the back teeth every day with a small headed toothbrush and interdental brushes where you can reach.
• Rinse with warm salt water if the area feels tender, and see a dentist early rather than late.
• Keep up regular examinations, so a wisdom tooth coming through at an awkward angle is noticed early. Our dental examination includes X rays where they are needed.
• Tell your dentist if you have had gum swelling around a wisdom tooth before. They may suggest monitoring or removal.

Talk to a dentist

If you have a swollen gum around a wisdom tooth, a short examination usually tells you what is going on and what the options are. You do not need to wait for the pain to become severe. Bring a note of when it started and what you have been doing to ease it, and mention any medicines you take and any health conditions.

Pericoronitis FAQs

What does pericoronitis feel like?

Commonly a sore, swollen gum at the back of the mouth, a bad taste, and in more severe cases difficulty opening your mouth fully. Some people have only mild symptoms, so a dentist is the best person to tell you what it is.

Can pericoronitis go away on its own?

A mild episode can settle with cleaning, but it often returns while the tooth is still partly covered by gum. If the pain lasts more than three or four days or gets worse, see a dentist.

Is pericoronitis serious?

It can be mild, but infection can spread to the jaw, face and neck. Trouble opening your mouth, swelling that spreads, fever, or difficulty swallowing or breathing need urgent help.

Can I treat pericoronitis at home?

You can ease symptoms with gentle cleaning, warm salt water rinses and pain relief as directed. Home care does not treat the cause, so have it checked. Do not cut or pick at the gum.

Do I need antibiotics for pericoronitis?

Not always. A dentist often starts with cleaning under the gum flap. Antibiotics may be considered when infection is spreading or there is trismus, and a dentist or doctor decides. Do not take leftover medicines.

Will I need my wisdom tooth removed?

Not always. A tooth that is not causing problems is usually monitored. Removal is generally discussed when infections keep coming back or the tooth causes other problems. The decision depends on your tooth and your health.

How long does pericoronitis last?

An episode can last from a few days to longer, depending on how it is treated and whether the cause is dealt with. Because it often recurs, a dentist may suggest a longer term plan.

What is the difference between pericoronitis and a dental abscess?

Pericoronitis is inflammation and infection of the gum around a partly erupted tooth. A dental abscess is a collection of pus, often at the root of a tooth or in the gum. They can feel alike, so a dentist examines you to tell them apart.