Dentin is a type of tissue and one of the four components which form a tooth. Dentin is the tissue which lies beneath the enamel. The enamel is the outer surface of the tooth. Dentin is mostly formed by the mineral hydroxylapatite. The natural color of dentin is yellowish. As the enamel is semi-translucent, the color of the dentin plays a significant role in giving the tooth a color. The dentin effectively supports the enamel from the inside.

If you take a microscopic look, you would find that certain channels exist in the dentin which flow from the pulp towards the cementum and the enamel. The dentin possesses permeability to some extent and hence, pain and sensation is felt in the dentin.

There are three types of dentin:

  • Primary dentin: this is the dentin type which forms the major part and exists between the pulp and enamel. The dentin layer which is connected to the enamel is called the mantle dentin.
  • Secondary dentin: when a tooth has erupted completely and it starts to function properly, and when the root formation is completed, the secondary dentin gets formed. The rate of growth of the secondary dentin is slower than the primary dentin.
  • Tertiary dentin: is the dentin which is formed as a response to any condition or external stimulation, for instance, cavities.