Hardest substance in teeth:
Ref: Grays Anatomy 40th edition 509, histology ross pawlina 6th edition 536Explanation:Enamel is produced by ameloblast and dentin is produced by neural cest derived odontoblastIt is the hardest and most highly mineralized substance in the human bodyEnamel is made of 96% inorganic mineral (calcium hydroxyapatite), with water and organic material composing the rest.It covers the anatomical crown and must be supported by underlying dentin.the visible part of the enamel is called as clinical crownIn humans, enamel varies in thickness over the surface of the toothThickest at the cusp, up to 2.5 mmThinnest at its border with the cementum at the cementoenaniel junction (CEJ).The normal color of enamel varies from light yellow to grayishtbluish i white. At the edges of teeth where there is no dentin underlying the enamel, the color sometimes has a slightly blue tone.Enamel is semitranslucent, the color of dentin and any material underneath the enamel strongly affects the appearance of a tooth.The enamel on primary teeth has a more opaque crystalline form and thus appears whiter than on permanent teeth.calciumhydroxyapatite, accounts not only for its strength but also for its brittleness.On radiographs, the differences in the mineralization of different portions of the tooth and surrounding periodontium can be noted; enamel appears more radiopaque (or lighter! than either dentin and pulp since it is denser than both, both of w hich appear more radiolucent (or darker).Despite its hardness, enamel can be decalcified by acid producing bacteria acting on food products trapped on the enamel surface leading on to dental caries. (See the following figure)
Cementum
Enamel
Pulp
Dentin
Oral Cavity & Tongue