Gum swelling at back of mouth
Back-of-mouth swelling may involve an erupting wisdom tooth, gum pocket, decayed molar, or deeper dental infection.
The short answer
Swelling at the back of the mouth may involve the gum around a partially erupted wisdom tooth, a periodontal pocket, a decayed molar, or an infection in the tooth or surrounding tissue.
Why can gum behind the last molar become swollen?
The tissue behind the last molar can form a flap over an erupting third molar, trapping plaque and food. Examination may include probing, checking jaw opening and swallowing, and a radiograph to assess the tooth’s position and roots.
How can you keep swollen back gum clean safely?
Keep the area as clean as you can with a small soft brush, rinse gently, and avoid picking under the gum flap. Use only pain medicine that is suitable for you and follow its label or clinical advice.
When is swelling at the back of the mouth urgent?
Seek urgent care for spreading swelling, fever, pus, worsening pain, difficulty opening the mouth, or any difficulty swallowing or breathing.
What could be causing swelling behind the last molar?
Ask whether the swelling is pericoronitis, decay, periodontal disease, or a deeper infection; whether cleaning, drainage, root canal treatment, or removal is needed; and what prevents another episode.
Frequently asked questions
Why can gum behind the last molar form a flap?
The tissue behind the last molar can form a flap over an erupting third molar, trapping plaque and food. Examination may include probing, checking jaw opening and swallowing, and a radiograph to assess the tooth’s position and roots.
What can I do now?
Keep the area as clean as you can with a small soft brush, rinse gently, and avoid picking under the gum flap. Use only pain medicine that is suitable for you and follow its label or clinical advice.
When is care urgent?
Seek urgent care for spreading swelling, fever, pus, worsening pain, difficulty opening the mouth, or any difficulty swallowing or breathing.
Who wrote this page
This library is published by Dental Nation, a licensed dental group practising in the United Arab Emirates. Pages are written and overseen by the same clinical team that treats patients in our clinics, and are held to a fixed editorial standard for safety and accuracy.
This page is patient education, not medical advice, and cannot replace an examination. Anything urgent — facial swelling, trauma, uncontrolled bleeding or severe pain — needs a dentist or emergency care now.