← All explanationsEruption cyst

What is a bluish swelling over an erupting tooth?

An eruption cyst is a fluid-filled swelling in the gum over a tooth coming through. Blood may give it a bluish colour. It often opens as the tooth erupts, but colour alone cannot establish the diagnosis.

For training & practice ↓

A bluish soft-tissue dome on the tooth-bearing ridge overlies an erupting tooth crown. — Bluish swelling · fictional teaching model

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Above the crown

The swelling is in soft tissue above a tooth shortly before it enters the mouth. Both primary and permanent teeth can be affected.

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Watch the eruption

A confirmed, uncomplicated eruption cyst often needs no procedure. Fluid may drain as the tooth emerges.

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Review changes

Pain, further enlargement or suspected infection needs assessment. Persistence after eruption or for around two weeks should prompt another review.

Read the full explanation

Above the crown
The swelling is in soft tissue above a tooth shortly before it enters the mouth. Both primary and permanent teeth can be affected.
Watch the eruption
A confirmed, uncomplicated eruption cyst often needs no procedure. Fluid may drain as the tooth emerges.
Review changes
Pain, further enlargement or suspected infection needs assessment. Persistence after eruption or for around two weeks should prompt another review.

Notes on the teaching images

Bluish swelling · fictional teaching model
Above the crown and the bony crest
Same model · have the course assessed

Watch the short explanation ↓

At a glance

Does blue mean blood?

It can indicate blood in the fluid.

Only baby teeth?

Permanent teeth can be affected too.

Wait despite pain?

No; seek timely advice.

Knowledge in motion

Explained in 36 seconds.

Three steps. No audio.
Each scene can also be selected manually.

Silent educational film with German on-screen text and simplified teaching images. Not a patient case or a promised treatment outcome. The full English explanation is available as text.

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Often confused

Soft tissue or jawbone?

An eruption cyst lies in soft tissue above an emerging tooth. A dentigerous cyst involves the region around a tooth crown within the jaw.

Quick answers

Is it an abscess?

Not automatically. Not every swelling is an eruption cyst; symptoms and progression must fit.

Should I open the swelling?

No. A dental professional treats the area if necessary.

Is surgery always needed?

Usually not. However, an enlarging or troublesome lesion may require treatment.

At the practice

For the appointment

You can bring this question to your appointment:

Does this swelling fit tooth eruption, and when should it be reviewed?

An examination can clarify the finding and any need for referral.

Arrange an assessmentAppointment selection at Doctolib

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Learning layer for training & practiceUnderstand terminology and deepen knowledge

Eruption: A tooth emerging into the mouth.
Haematoma: A collection of blood; a possible reason for the colour here.

Make the distinction

An eruption cyst lies in soft tissue above an emerging tooth. A dentigerous cyst involves the region around a tooth crown within the jaw.

Knowledge questionWhat is appropriate?

For learning, not for assessing personal symptoms. Your answer is not stored or sent.

Have uncertain or persistent swelling assessed.
Pierce every blue swelling yourself.
Assume every blue area is harmless.

View answer

Have uncertain or persistent swelling assessed.

A typical colour does not replace examination.

Sources and context

Editorial research: 2026-11-09. General information, not an individual diagnosis or treatment recommendation. Teaching illustrations are simplified and do not depict a patient case.