Zones of Dentinal Caries

ZONES OF DENTINAL CARIES
ZONE 1	Normal Dentin
Zone 2	Subtransarent Dentin	Zone of demineralization (by acid from caries) Damage to the odontoblastic process is evident. However, no bacteria are found in the zone. Stimulation of the dentin produces pain, and the dentin is capable of remineralization.
Zone 3	Transparent dentin	Softer than normal dentin Further loss of mineral from the intertubular area. Stimulation of this region produces pain. There are no bacteria present. The collagen cross-linking remains intact in this zone, can serve as a template for remineralization. The intact collagen of the intertubular dentin, and thus this region remains capable of self-repair, provided the pulp remains vital.
Zone 4	Turbid dentin	Turbid dentin is the zone of bacterial invasion  Widening and distortion of the dentinal tubules which are filled with bacteria. There is very little mineral present and the collagen in this zone is irreversibly denatured. The dentin in this zone will not self-repair. This zone cannot be remineralized and must be removed prior to restoration
Zone 5	Infected Dentin	The outermost zone, infected dentin, consists of decomposed dentin that is teeming with bacteria. There is no recognizable structure to the dentin. Absence of collagen and mineral content. Great numbers of bacteria are dispersed in this granular material. Removal of infected dentin is essential to sound, successful restorative procedures as well as prevention of spread of the infection