<Tr> <Th> FMA </Th> <Td> 55628 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> Dentin (/ ˈdɛntɪn /) (American English) or dentine (/ ˈdɛnˌtiːn / or / ˌdɛnˈtiːn /) (British English) (Latin: substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth . It is usually covered by enamel on the crown and cementum on the root and surrounds the entire pulp . By volume, 45% of dentin consists of the mineral hydroxylapatite, 33% is organic material, and 22% 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 which distinguish dentine from enamel; firstly dentine forms throughout life, and secondly, dentine is sensitive . </P> <P> 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 . </P>

There are 2 layers of dentine – what lies between