Editing Human tooth (section)

===Enamel===
{{Main|Tooth enamel}}

Enamel is the hardest and most highly [[mineralized tissues|mineralized substance]] of the body. It has its origin from oral [[ectoderm]]. It is one of the four major tissues which make up the tooth, along with [[dentin]], [[cementum]], and [[dental pulp]].<ref>{{harvnb|Ross|2002|page=441}}</ref> It is normally visible and must be supported by underlying dentin. 96% of enamel consists of mineral, with water and organic material comprising the rest.<ref>{{harvnb|Cate|1998|page=1}}</ref> 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 (dentistry)|cusp]], up to 2.5mm, and thinnest at its border, which is seen clinically as the CEJ.<ref name="Cate, A. R 1998 p. 219">{{harvnb|Cate|1998|page=219}}</ref> The wear rate of enamel, called attrition, is 8 micrometers a year from normal factors.<ref>{{Cite web | url=http://www.dd-database.org/dental/tooth-enamel.html | title=Tooth enamel &#124; Drug Discrimination Database}}</ref>

Enamel's primary [[mineral]] is [[hydroxyapatite]], which is a [[crystal]]line [[calcium phosphate]].<ref name = "biology"/> The large amount of minerals in enamel accounts not only for its strength but also for its brittleness.<ref name="Cate, A. R 1998 p. 219"/> Dentin, which is less mineralized and less brittle, compensates for enamel and is necessary as a support.<ref name="biology">Johnson, Clarke (1998). "[http://www.uic.edu/classes/orla/orla312/BHDTwo.html Biology of the Human Dentition] {{webarchive|url=https://web.archive.org/web/20151030052831/http://www.uic.edu/classes/orla/orla312/BHDTwo.html |date=2015-10-30 }}". uic.edu.</ref> Unlike dentin and [[bone]], enamel does not contain [[collagen]]. [[Protein]]s of note in the [[tooth enamel#Development|development]] of enamel are [[ameloblastin]]s, [[amelogenin]]s, [[enamelin]]s and [[tuftelin]]s. It is believed that they aid in the development of enamel by serving as framework support, among other functions.<ref>{{harvnb|Cate|1998|page=198}}</ref> In rare circumstances enamel can fail to form, leaving the underlying dentine exposed on the surface.<ref>{{Cite web|url=https://www.researchgate.net/publication/319987728|title=Severe Plane-Form Enamel Hypoplasia in a Dentition from Roman Britain|website=ResearchGate|language=en|access-date=2019-01-09}}</ref>