Composition classification and function of teeth

Composition, classification and function of teeth
Composition (1) of the tooth , in view of appearance, the tooth is made up of the corona, the root of the tooth and part of neck three 1, corona: Refer to the part covered by the enamel of tooth, give play to chewing the main part of the function too. It refers to the corona taking tooth shank as circle to dissect and preceded. It means what saw in the oral cavity was exposed to the part of body of tooth beyond the gingivae to preceded clinically. Its corona and root of the tooth make gingivae reason as the boundry. 2,The root of the tooth: Refer to the part that the tooth is covered by tooth ossicle. 3,Neck: Called the neck in corona and intersection of the root of the tooth, because it takes the form of a arcual curve, also called the line of neck. The classification of the tooth: (1) , classify 1 according to shape and function, incisor: Lie in front part of oral cavity, totally 8, its main function, in order to cut the food. 2,Sharp tooth: Lie in an angle, totally 4, the corona is stalwart, the root of the tooth is long but thick, the main function is for puncturing and tearing the food. 3,Premolar teeth: Also called one pair of sharp teeth, lie behind sharp tooth, before grinding one's teeth, totally 8. Its main function is for assisting the sharp tooth to tear and assist to grind one's teeth and mash the function of the food. 4,Grind one's teeth: Lie behind premolar teeth, totally 12, the structure is complicated, function is to rub the garrulous food. Incisor and sharp tooth lie in front part of the vestibule of oral cavity, before the corner of the mouth, the tooth before called jointly; Premolar teeth and grinding one's teeth to lie behind corner of the mouth, call the backtooth jointly. (2) , according to existing to classify 1, deciduous teeth for a long time temporarily: Can be divided into milk incisor, milk sharp tooth, three kinds milk grinding teeth. From born for about 6 months to about 6 year olding, there are deciduous teeth in the oral cavity, this period is called deciduous teeth listing period. From about 6 years old to 13-14 years old, deciduous teeth loss and are replaced by permanent tooth and had deciduous teeth in the oral cavity of this period gradually, have permanent tooth, are called and mixed the tooth and listed one. 2,Permanent tooth: Can be divided into incisor, sharp tooth, premolar teeth, ground one's teeth. Permanent tooth to continue deciduous teeth, take off backward the intersection of second mate and the intersection of tooth and row, sprout, appear while being about 6 year old, 13-14 years old later, deciduous teeth have already been all substituted by the permanent tooth, so been called the permanent tooth and list one. The function of the tooth: (1) , chew (2) , pronounce and the language (3) , the normal shape of maintenance face

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