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TeethAnswering Service > Call Center Resource > Health and Fitness > Teeth
Small, bone-like structures of the jaws used for the biting and chewing of food. They are firmly anchored in the alveolar bone of the jaws, and project from the gums. The number, arrangement, and type of teeth varies between different animals. Some animals have two sets (eg most mammals); others have several rows which gradually move forwards as others are lost (eg sharks). Each tooth consists of a core of pulp surrounded by dentine, which is covered in its upper part by enamel and in its lower part by cement (essentially bone). The crown is the enamel-covered part that projects beyond the gums; it may have one or more projections called cusps. The surfaces of the crowns form the occlusal surfaces, which meet when the upper and lower teeth are brought together. The cement-covered part of the tooth is the root, and is firmly attached to the bone of the alveolar socket by the peridontal membrane. The pulp and dentine have an extensive blood and nerve supply. In many mammals, different types of teeth can be identified: incisors for cutting, canines for cutting and tearing, and premolars and molars for grinding. In humans the first set of teeth (deciduous or milk teeth) usually appears between 6 and 24 months of age, there being 20 deciduous teeth in all (2 incisors, 1 canine, and 2 molars in each half-jaw). These gradually become replaced (from about age 6) by the permanent teeth, with the addition of 3 more teeth in each half-jaw giving a total complement of 32 (2 incisors, 1 canine, 2 premolars, 3 molars in each half-jaw). The third molar is often referred to as the wisdom tooth, because of its time of eruption. Not all of the teeth may appear.
(http://www.reference.com/browse/crystal/31254)
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