Hard tissue made up of various salts. Enamel is the hardest substance in the human body and contains the highest percentage of minerals, 96%, with water and organic material composing the rest. The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. Enamel is formed on the tooth while the tooth is developing within the gum, before it erupts into the mouth. Once fully formed, it does not contain blood vessels or nerves. Remineralisation of teeth can repair damage to the tooth to a certain degree but damage beyond that cannot be repaired by the body. The maintenance and repair of
Crownshaft It is usually green in color but may be a different color from that of the leaves themselves, including white, blue, red, brownish or orange. Each layer of the crownshaft is a distinct leaf base and is usually made of a tough fibrous material with a feel similar to leather and in many parts of the world, it is cured and used to prepare covers, sheets and roofing material. The leaf base of some palms are also used to extract coir. The oldest leaf forms the outermost layer of the crownshaft. Eventually the lowest palm frond dies back, the outer