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Ivory is a hard, white, opaque substance that is the bulk of the teeth and tusks of animals such as the elephant, hippopotamus, walrus, etc. Prior to the introduction of plastics, it was used for billiard balls, piano keys, buttons and ornamental items.

The word "ivory" was traditionally applied to the tusks of elephants. However, the chemical structure of the teeth and tusks of mammals is the same regardless of the species of origin, and the trade in certain teeth and tusks other than elephant is well established and widespread. Therefore, "ivory" can correctly be used to describe any mammalian teeth or tusks of commercial interest which is large enough to be carved or scrimshawed.

Teeth and tusks[?] have the same origins. Teeth are specialized structures adapted for food mastication. Tusks, which are extremely large teeth projecting beyond the lips, have evolved from teeth and give certain species an evolutionary advantage. The teeth of most mammals consists of a root and the tusk proper.

Teeth and tusks have the same physical structures: pulp cavity[?], dentine, cementum[?] and enamel[?]. The innermost area is the pulp cavity. The pulp cavity is an empty space within the tooth that conforms to the shape of the pulp.

Odontoblastic cells[?] line the pulp cavity and are responsible for the production of dentine. Dentine, which is the main component of carved ivory objects, forms a layer of consistent thickness around the pulp cavity and comprises the bulk of the tooth and tusk. Dentine is a mineralized connective tissue with an organic matrix of collagenous proteins. The inorganic component of dentine consists of dahllite. Dentine contains a microscopic structure called dentinal tubules which are micro-canals that radiate outward through the dentine from the pulp cavity to the exterior cementum border. These canals have different configurations in different ivories and their diameter ranges between 0.8 and 2.2 microns. Their length is dictated by the radius of the tusk. The three dimensional configuration of the dentinal tubules is under genetic control and is therefore a characteristic unique to the order.

Tooth and tusk ivory can be carved into an almost infinite variety of shapes and objects. A small example of carved ivory objects are small statuary, netsukes[?], jewelry, flatware handles, furniture inlays, and piano keys. Additionally, warthog tusks, and teeth from sperm whales[?], killer whales and hippos can also be shrimshawed or superficially carved, thus retaining their original shapes as morphologically recognizable objects.

Due to the rapid decline in the populations of the animals that produce it, the importation and sale of ivory in many countries is banned or severely restricted. A species of hard nut is gaining popularity as a replacement for ivory, although its size limits its usability.

See Also: Elephant and Mammoth ivory, Walrus ivory, Sperm Whale and Killer Whale ivory[?], Narwhal ivory[?], Hippopotamus ivory[?], Warthog ivory[?]

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