is the hardest and most highly mineralized substance of the body, and with dentin
, and dental pulp
is one of the four major tissues which make up the tooth
. It is the normally visible dental tissue of a tooth and must be supported by underlying dentin. Ninety-six percent of enamel consists of mineral, with water
and organic material
composing the rest. The normal color
of enamel varies from light yellow to grayish white. At the edges of teeth where there is no dentin underlying the enamel, the color sometimes has a slightly blue tone. Since enamel is semitranslucent
, the color of dentin and any restorative
dental material underneath the enamel strongly affects the appearance of a tooth. Enamel varies in thickness over the surface of the tooth and is often thickest at the cusp
, up to 2.5 mm, and thinnest at its border, which is seen clinically as the cementoenamel junction
Enamel's primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. The large amount of minerals in enamel accounts not only for its strength but also for its brittleness. Dentin, which is less mineralized and less brittle, compensates for enamel and is necessary as a support.
Unlike dentin and bone, enamel does not contain collagen. Instead, it has two unique classes of proteins called amelogenins and enamelins. While the role of these proteins is not fully understood, it is believed that they aid in the development of enamel by serving as a framework support, among other functions.