Swelling behind back tooth
Swelling behind a back tooth can come from an erupting wisdom tooth, gum inflammation, trapped debris, infection, or a nearby salivary tissue.
The short answer
Swelling behind a back tooth is commonly related to inflamed gum over an erupting wisdom tooth, food trapped beneath the gum, a cavity or infection in the tooth, or irritation from biting. The cause is identified by examining the gum and tooth and, when needed, taking a dental X-ray.
What is the direct answer?
What does this question mean?
The area behind the last molar may contain a partially erupted wisdom tooth and a gum flap called an operculum. That flap can trap plaque and food, while a decayed or cracked molar can inflame the surrounding tissues and produce swelling near the cheek or jaw.
What can you do next?
Rinse gently with warm water, brush the area carefully with a small-headed brush, and keep food from packing around the tooth. Do not cut the gum, squeeze a lump, or place aspirin directly on the tissue; a dentist may irrigate the pocket, treat decay, or plan wisdom-tooth care after examination.
When should you seek dental care?
Seek urgent care for spreading facial swelling, fever, pus, worsening pain, reduced mouth opening, or difficulty swallowing or breathing. Arrange a dental appointment even without those signs if the swelling lasts, recurs, or is attached to a tooth that cannot be cleaned properly.
What should you ask the dentist?
Ask whether the swelling is over a wisdom tooth, around a decayed molar, or in another tissue. Ask whether an X-ray is needed, how the area should be cleaned, and whether treatment requires drainage, restoration, gum-flap care, or removal of a tooth.
Frequently asked questions
Can trapped food cause a lump there?
Yes. Food and plaque beneath an inflamed gum flap can make the tissue swollen and tender, although a tooth infection must also be considered.
Should I pop the swelling?
No. Squeezing or puncturing it can injure tissue and may spread contamination; examination is needed to identify the source.