When a Wisdom Tooth Swells and Hurts

Name: When a Wisdom Tooth Swells and Hurts
Creator: Jongbum Lee

A swollen wisdom tooth is usually not a problem with the tooth itself, but inflammation "under the gum covering it." With a partially erupted wisdom tooth, food gets under the gum flap and can't be cleaned out, causing repeated inflammation (pericoronitis). A wisdom tooth that has swollen once tends to swell again. So rather than waiting to see if it's fine once the swelling goes down, the first step is to check whether this wisdom tooth needs to come out and how close it is to the nerve.

When a wisdom tooth swells and hurts, what are the common causes?

Pericoronitis — inflammation under the gum flap. It causes swelling, difficulty opening the mouth, and pain when swallowing. This is the most common cause.
Wisdom tooth cavity — the toothbrush can't reach, so the wisdom tooth and the back of the tooth in front of it decay together. This is how a wisdom tooth can end up costing you a perfectly healthy molar.
A horizontally impacted wisdom tooth pushing the tooth in front — a dull pressure, and resorption of that tooth's root.
Cyst — this can form around an impacted wisdom tooth and grow without symptoms, sometimes only found on a CT scan.

What should I check at home first?

Location of the swelling — whether it's the gum behind the very last molar, or has spread to the cheek.
Mouth opening — if two fingers don't fit, the inflammation has spread into the muscle.
Whether it recurs — a second episode or more is a sign to consider extraction even if it settles down.
Fever or pain when swallowing — if present, it needs to be checked that same day.

While it's swollen, rinse with lukewarm salt water and gently clean the area. If the swelling is severe, it's safer to calm the inflammation first and then extract.

What does the dentist check?

A panoramic X-ray shows the direction and depth of the impacted wisdom tooth, and for a lower wisdom tooth we check the distance to the inferior alveolar canal with 3D CT (CBCT). If the root is attached to or resting against the nerve canal, the extraction method changes (sectioning, removing only the crown, etc.), and that judgment is key to avoiding numbness after extraction. We also check for a cavity at the back of the tooth in front. More detail is on the wisdom tooth extraction page.

How does treatment proceed depending on the situation?

A properly erupted wisdom tooth with no inflammation → We may leave it if you can keep it clean. The deciding factor is whether your toothbrush can reach it.
A partially erupted wisdom tooth with recurring inflammation → Extraction. If the inflammation is severe, we calm it down first.
A horizontally impacted wisdom tooth → We open the gum and section the tooth to remove it. Why the gums kept swelling — a case of extracting a horizontally impacted wisdom tooth in sections.
Fully impacted, close to the nerve canal → We check the position with a CT scan and section it along the direction of the root to remove it. A case of a fully impacted wisdom tooth close to the nerve canal.

If you've ever felt shaky after anesthesia, please let us know beforehand. We've written up how we handled extraction in that kind of case.

Don't put it off in these cases

Swelling has reached the cheek or jaw, or you have a fever — the inflammation is spreading.
You can't open your mouth very wide.
Even the molar in front feels sensitive or hurts — this could mean a cavity is starting in that molar.

Related Treatments & Cases

FAQ

Can it be pulled right away while it's swollen?

If the swelling is mild, same-day extraction is possible. But if you can barely open your mouth, anesthesia doesn't work as well and infection risk rises, so we calm the inflammation first, then extract. We'll decide after an exam.

How much swelling should I expect after wisdom tooth extraction?

It varies with how the tooth is positioned, but swelling usually peaks on day 2–3 and mostly settles within a week. We manage it with cold compresses and prescribed medication.

How high is the risk of nerve damage?

It depends on the distance between the root and the nerve canal. Checking in advance with a CT scan and extracting in sections along the direction of the root can greatly reduce the risk. If they're close, we'll explain that and the alternatives first.

References

The order of evaluation and treatment approach described here are Boston Miso Dental Clinic's own standard; the causes, mechanisms and treatment effects are based on the references below.

Rood JP, Shehab BA. The radiological prediction of inferior alveolar nerve injury during third molar surgery. Br J Oral Maxillofac Surg. 1990;28(1):20-25. doi:10.1016/0266-4356(90)90005-6.
— Radiographic criteria for predicting the relationship between a wisdom tooth's root and the inferior alveolar canal.
Renton T, Hankins M, Sproate C, McGurk M. A randomised controlled clinical trial to compare the incidence of injury to the inferior alveolar nerve as a result of coronectomy and removal of mandibular third molars. Br J Oral Maxillofac Surg. 2005;43(1):7-12. doi:10.1016/j.bjoms.2004.09.002.
— A randomized study showing that removing only the crown (coronectomy) reduces nerve injury in wisdom teeth close to the nerve canal.
Ghaeminia H, Nienhuijs ME, Toedtling V, et al. Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth. Cochrane Database Syst Rev. 2020;5:CD003879. doi:10.1002/14651858.CD003879.pub5.
— Evidence for the judgment that a symptom-free wisdom tooth doesn't always need to come out and can sometimes be left in place.

※ This guide is general information. Even with the same symptom, the cause and the right treatment vary with your oral health. Dr. Lee, the Clinic Director, explains your diagnosis in person after an exam. Any dental treatment can cause side effects such as pain, bleeding, or infection, which vary from person to person.

The clinician responsible for treatment guidance at Boston Miso Dental Clinic is Dr. Jongbum Lee, Clinic Director, a board-certified specialist in Advanced General Dentistry (Korea).