1.      Sclerotic zone (translucent zone) A demarcation zone which separates an affected tissue from sound dentin

·        Tubular sclerosis

·        Calcification of the odontoblast processes

·        Redeposition of minerals represents a defense mechanism of dentin

·        Can be found Dead tracts

2.      Demineralization  zone (dark zone) increased loss of minerals in the dentin

3.      Zone of bacterial invasion increase number of destroyed dentinal tubules

• The spaces are filled with bacteria and products prevail followed by proteolysis of the organic tissue.

4.      Zone of destruction filled with masses of destroyed dentin tissue, bacteria and their metabolic products

• Clinically can be seen an overt cavity.

5.      Reactive dentin non specific defense reaction of the pulp to injury. Due to active dentin production by odontoblasts zones of unequal mineralization and chaotic structure of the tubules are present.