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tooth
(tldbomacth)
pl. teeth
one of the small bonelike structures of the upper and lower jaws for biting and chewing of food; they also help in the shaping of sounds and forming of words in speech. The part above the gum is the crown, and that below the gum is the root. The crown is covered by enamel, which is related to the epithelial tissue of the skin and is the hardest substance in the human body. The surface of the
root is composed of a bonelike tissue called cementum. Underneath the surface enamel and cementum is a substance called dentin, which makes up the main body of the tooth. Within the dentin, in a space in the center of the tooth, is the dental pulp, a soft, sensitive tissue that contains nerves, blood vessels, and lymph vessels. The root of the tooth sits in an alveolus (socket) in the jawbone.There are 20 primary or deciduous teeth, which are later replaced by 32 permanent teeth, evenly divided between the upper and lower jaws.
Schematic cross section of an anterior (left) and a posterior (right) tooth in the maxilla.
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