1. One of the hard conic structures set in the alveoli of the upper and lower jaws, used in mastication and assisting in articulation. A tooth is a dermal structure composed of dentin and encased in cementum on the anatomic root and enamel on its anatomic crown. It consists of a root buried in the alveolus, a neck covered by the gum, and a crown, the exposed portion. In the center is the pulp cavity filled with a connective tissue reticulum containing a jellylike substance (dental pulp) and blood vessels and nerves that enter through an aperature or aperatures at the apex of the root. The 20 deciduous teeth or primary teeth appear between the 6th–9th and the 24th months of life; these exfoliate and are replaced by the 32 permanent teeth appearing between the 5th–7th years and the 17th–23rd years. There are four kinds of teeth: incisor, canine, premolar, and molar.
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