Swelling behind last molar

Swelling behind the last molar often involves an erupting wisdom tooth, trapped food, gum inflammation, or a dental infection.

The tissue behind a second molar may partly cover an erupting third molar, creating a flap where plaque and food collect. Similar swelling can also arise from decay, a gum pocket, trauma, or an abscess in a nearby tooth.

Rinse gently with warm salt water, brush the accessible surfaces, and avoid squeezing or cutting the swelling. A dental examination may include probing, a bite check, and an X-ray to locate the cause.

Arrange prompt care for worsening pain, pus, bad taste, fever, limited mouth opening, or swelling that returns. Emergency assessment is needed if swelling spreads toward the eye or neck or affects breathing or swallowing.

Ask whether the wisdom tooth has enough room to erupt and whether the swelling is around the tooth or coming from an abscess. Ask which treatment is needed, such as cleaning, restoration, drainage, or removal.