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pl. teeth Any of the hard, bony structures of the upper and lower jaws used for cutting, tearing and chewing. A tooth consists of a crown portion above the gum, a root portion embedded in a socket (alveolus) of the jaw bone, and a neck or cervical constricted region between the crown and root. The soft-tissue gingiva covers the neck and root to a variable extent, depending on age and oral hygiene. The major portion of a tooth consists of dentin, which is harder than bone; enamel; and cementum, which is similar to bone. The pulp cavity contains the dental pulp. Each tooth has five surfaces: occlusal, mesial, distal, lingual, and facial or buccal.
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STRUCTURE OF A TOOTH (longitudinal section); SEE: dentition
Every human has two complete sets of teeth during his or her life. The 20 primary teeth are the first set of teeth to develop. They exfoliate by age 14 and are replaced by the 32 permanent teeth. The permanent teeth include the incisors, canines (cuspids), premolars (bicuspids), and molars. On average, a child should have 6 teeth at 1 year, 12 teeth at 18 months, 16 teeth at 2 years, and 20 teeth at 12 years. Some children are born with a few erupted teeth; in other children the teeth may not appear until 16 months.

Health care professionals should assess patients’ teeth and gums during physical examinations, educate patients about routine dental hygiene (brushing, flossing, gum stimulation, use of oral rinses), and refer them to a dental professional for dental caries, eruption anomalies, or periodontal problems.

SEE: dental plaque; SEE: periodontal disease

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