Dentin is considered as a vital tissue and has the capacity to respond to physiologic and pathologic stimuli.
As it is known, dentin is covered by enamel in the crown surface and by a thin layer of cementum in the
root surface of the tooth. Dentin is sensitive to stimuli due to the lesion extension of odontoblastic process and
formation of dentin-pulp complex.
Dentin and pulp are histologically different. However, they have the same embryonic origin; ectomesenchymal
origin. The formation of dentin-pulp causes dentin to be affected by pulp and vice versa. Dentin has
very minute tubules which are filled with odontoblastic process. The processes are also surrounded by dentinal
fluid which forms about 22% of the total volume of dentin. The fluid is completely filtrated and originates
from the blood vessels of the pulp