Dentin is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surrounds the entire pulp. By weight, seventy percent of dentin consists of the mineral hydroxylapatite, twenty percent is organic material and ten percent is water. Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel.
Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel. Dentin rates approximately 3 on the Mohs scale of mineral hardness. There are two main characteristics that distinguish dentin from enamel: firstly, dentin forms throughout life; secondly, dentin is sensitive.
Dentinal sclerosis/transparent dentin-sclerosis of primary dentin is regressive alteration in tooth characterized by calcification of dentinal tubules. It can occur as a result of injury to dentin by caries or abrasion, or as part of the normal aging process.