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Cariology & Operative DentistryBasic

Stages of caries

Caries progresses from the outside in: enamel → dentin → pulp. While it is only in the enamel, it can still be remineralized.
Cavitated caries on the distal surface of a lower first molar (Black's Class II): the enamel has already broken.
Cavitated caries on the distal surface of a lower first molar (Black's Class II): the enamel has already broken.Photo: Ickyvickywiki · CC BY-SA 4.0, Wikimedia Commons

What you need to know

  • Enamel: it starts as an opaque white spot lesion and does not hurt. It can be remineralized with fluoride, better hygiene and checkups.
  • Dentin: a cavity appears, along with pain from cold, heat or sweets. It is treated by removing the caries and restoring the tooth.
  • Pulp: inflammation of the pulp (pulpitis) causes intense, lasting pain.
  • If it is not treated, the pulp dies and an abscess can form at the tip of the root.
  • Radiographs are the most important tool for finding caries and seeing how deep it is.

ICDAS codes (what the caries looks like)

CodeWhat you see
0Sound surface
1First change in the enamel (only seen after drying)
2Distinct change in the enamel (seen when wet)
3Small break in the enamel
4Dark shadow from the dentin underneath
5Cavity with visible dentin
6Large cavity (more than half of the surface)

Terms in plain words

DemineralizationLoss of minerals from the tooth caused by acid from bacteria.
RemineralizationRecovery of those minerals, helped by saliva and fluoride.
CavitationWhen the surface breaks and a hole is left.

For the exam

At what stage can caries still be reversed without drilling?

Show answerHide answer

When it is only in the enamel (initial lesion): it is remineralized with fluoride, hygiene and checkups.

Sources

  1. Hennessy BJ. Caries. MSD Manual, Professional Version (2026 revision). View source
  2. Gugnani N, et al. International Caries Detection and Assessment System (ICDAS): A New Concept. Int J Clin Pediatr Dent. 2011. View source
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