← All explanationsCaries activity

Can a decay lesion become inactive?

Yes. A carious lesion can be active or arrested. Activity describes the likelihood of progression at a particular site. Assessment considers the surface, location, plaque and changes over time. Colour alone is insufficient.

For training & practice ↓

Pale enamel patch used as a simplified teaching image — Lustre, surface texture and location can provide clues. Activity cannot be determined from this synthetic image.

01 / 03

Assess the surface

Matt or rough enamel can differ from smooth, shiny surfaces. A clinician assesses this gently and in context.

02 / 03

Consider the surroundings

Plaque, access for cleaning and the individual's situation influence the assessment. One observation does not prove activity.

03 / 03

Compare over time

Reviews show whether a finding changes. An arrested lesion still needs suitable care and monitoring.

Read the full explanation

Assess the surface
Matt or rough enamel can differ from smooth, shiny surfaces. A clinician assesses this gently and in context.
Consider the surroundings
Plaque, access for cleaning and the individual's situation influence the assessment. One observation does not prove activity.
Compare over time
Reviews show whether a finding changes. An arrested lesion still needs suitable care and monitoring.

Notes on the teaching images

Lustre, surface texture and location can provide clues. Activity cannot be determined from this synthetic image.
Plaque, oral hygiene, fluoride and diet contribute to assessing caries risk.
Reviews help show whether a lesion remains stable or changes. Activity is not the same as lesion depth.

For your visit: open the communication cards

Watch the short explanation ↓

At a glance

Can decay become inactive?

Yes, arrest is possible.

How is it assessed?

Using several clinical features.

What remains important?

Care and agreed reviews.

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.

Go to film text

Often confused

Activity and individual risk

Activity concerns an existing lesion. Caries risk concerns the likelihood of new or progressing damage in a person.

Quick answers

Is dark decay always active?

No. Dark areas may be hard and inactive; pale changes can be active.

Does an arrested lesion mean the tooth is intact again?

No. Arrest does not mean lost tooth structure has grown back. An existing cavity requires separate assessment.

Can I test a mark with a needle?

No. Do not scratch or probe tooth marks yourself. This can damage surfaces and is not a reliable assessment.

At the practice

For a personal discussion

Editorially suggested question to discuss with Dr Niusha Barahmand Pour:

Which signs suggest that this lesion is active or arrested?

Concerned about a mark? An examination can clarify its nature and how it should be monitored.

Have a tooth change assessedAppointment selection at Doctolib

Meet Dr. Niusha Barahmand Pour ↗

Learning layer for training & practiceUnderstand terminology and deepen knowledge

Lesion: A localised tissue change.
Arrested: No longer progressing.
Monitoring: Comparing findings at different times.

Make the distinction

Activity concerns an existing lesion. Caries risk concerns the likelihood of new or progressing damage in a person.

Knowledge questionWhat does brown colour alone establish?

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

Neither activity nor arrest.
That drilling is immediately required.
That the area is certainly healthy.

View answer

Neither activity nor arrest.

Colour must be considered alongside other clinical features.

Sources and context

Editorial research: 2026-11-06. General information, not an individual diagnosis or treatment recommendation. Teaching illustrations are simplified and do not depict a patient case.