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
Radius of outermost closed isobar Radius of outermost closed isobar The radius of outermost closed isobar (ROCI) is one of the quantities used to determine the size of a tropical cyclone. It is determined by measuring the radii from the center of the storm to its outermost closed isobar in four quadrants, which is then averaged to come up with a scalar value. It generally delimits the outermost extent of a tropical cyclone's wind circulation. Use of this measure has objectively determined that tropical cyclones in the northwest Pacific Ocean are the largest on earth on average, with North Atlantic tropical cyclones roughly half their