[1] Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel.

[9] From the outer surface of the dentin to the area nearest the pulp, these tubules follow an S-shaped path.

It is made up, by weight, of 70–72% inorganic materials (mainly hydroxylapatite and some non-crystalline amorphous calcium phosphate), 20% organic materials (90% of which is collagen type 1 and the remaining 10% ground substance, which includes dentin-specific proteins), and 8–10% water (which is adsorbed on the surface of the minerals or between the crystals).

In these areas, only primary mineralization has occurred within the predentin, and the globules of dentin do not fuse completely.

It can be identified by the presence of various characteristics, including collagen fibres found perpendicular to the enamel-dentin junction and it is slightly less mineralized (by approximately 5%, compared to the enamel.

The dentin undergoes mineralization in the presence of matrix vesicles ("hydroxyapatite-containing, membrane-enclosed vesicles secreted by odontoblasts, osteoblasts, and some chondrocytes; believed to serve as nucleation centers for the mineralization process in dentin, bone, and calcified cartilage.

[4]: 134–137 During the dentinogenesis process, the odontoblast cells retreat from the DEJ to the outer lining of the pulp, leaving behind microtubules filled with cytoplasmic extensions and depositing intertubular dentin (ITD) in its place.

[16] ITD comprises the bulk of the dentin and, similarly to bone, is a matrix composite of tablet-shaped hydroxyapatite nanoparticles wrapped around collagen fibers.

The mineralized collagen fibers are arranged in layers oriented perpendicular to the direction of the dentin microtubules[17][18] which are lined with peritubular dentin (PTD), a 1-2 μm thick layer of hydroxyapatite tablets with no preferred orientation and lacks any supporting collagen fibers.

Since the PTD, the hydroxyapatite tablets are not preferentially orientated; they are under less compressive residual stress, causing the microtubules to act as crack initiation sites.

The tip of a larger crack creates a stress concentration that helps initiate microcracks around the microtubules ahead of it, consuming energy and resisting further damage.

[23] The combination of the residual stress and the perpendicular orientation of the ITD mineralized collagen fibers significantly increases the fracture toughness and fatigue endurance limit along the microtubule direction.

Previously it was thought that Pulp capping was most successful if followed by a stainless steel crown, however this procedure is most of the times unnecessary in children.

Adhesive dentistry allows for conservative restoration techniques that minimize the loss of tooth structure and should be used.

In order to maintain space in the primary dentition, attempts are made not to extract a pulpal exposure.

Thus, tertiary dentin is deposited rapidly, with a sparse and irregular tubular pattern and some cellular inclusions; in this case, it is referred to as "osteodentin".

However, if the stimulus is less active, it is laid down less rapidly with a more regular tubular pattern and hardly any cellular inclusions.

It can occur as a result of injury to dentin by caries or abrasion, or as part of the normal aging process.

Elephant tusks are formed with a thin cap of enamel, which soon wears away, leaving the dentin exposed.

Dentin is best known for its occurrence in teeth, but in early vertebrates, it was an important part of the dermal skeleton that covered most of the body,[29][30][31] and it persists today in a few taxa such as the coelacanth.

In many herbivores, the occlusal (biting) surface of the tooth is composed of alternating areas of dentin and enamel.

Herbivores grind their molars together as they chew (masticate), and the ridges help to shred tough plant material.

In xenarthrans, enamel is generally absent, with the tooth instead consisting of alternating orthodentine and vasodentine.