Modules
Module 3: Tooth Surface Assessment and Selection

3.2 Stages in Caries Lesion Severity and Activity

Active vs. Arrested Lesions

Non-cavitated occlusal caries lesionNon-cavitated occlusal caries lesion. It is difficult to determine whether the lesion is active or arrested simply by looking at the lesion.
Image courtesy of Margherita Fontana, D.D.S., Ph.D.

Caries lesions can be active or arrested. Active lesions exhibit evidence of progression or change over time, while arrested lesions do not. Thus, the only way to determine with certainty whether a lesion is active is to follow it over time and observe its changes.

However, oral health professionals prefer to make clinical assessments in real time rather than following patients over time. The following characteristics may help in determining whether a non-cavitated lesion is active without following a patient over time:

  • Active lesions tend to be whitish or yellowish in color and opaque (non-glossy). Inactive lesions can be whitish or yellowish in color but tend to be shiny or glossy.
  • Active lesions feel rough when the tip of the explorer is moved gently across their surface. Inactive lesions feel hard and smooth when the tip of the explorer is moved gently across their surface.
  • Active lesions are located close to the gingival margin when the lesion is in a smooth surface. Inactive lesions are located farther away from the gingival margin when the lesion is in a smooth surface.

When the lesion is in an occlusal surface, it is more difficult to differentiate between an active and an inactive lesion, because many such lesions are not easily visible to the naked eye or accessible to the gentle touch of the explorer, especially if the lesion does not extend beyond the confines of the pit-and-fissure system on the occlusal surface.

Only active caries lesions require management. The transition from a sound tooth to a non-cavitated lesion, from a non-cavitated lesion to a cavitated lesion, and from a cavitated lesion to irreversible pulpal infection does not always occur, and if these transitions do take place, they happen slowly. Thus, especially when managing the active, non-cavitated lesion (e.g., with fluoride varnish applications or dental sealants), there is no need to make quick and irreversible treatment decisions (i.e., placing a restoration).