|CENTRAL INCISORS VIA WIKIPEDIA|
The teeth of man vary in nature from the incisors to the molars and are referred to as heterodont. Man is prepared with two dentitions or sets of teeth. The first series of teeth in man is called the deciduous dentition and the second series the permanent dentition. The deciduous teeth are on occasion called the baby or milk teeth.
The teeth arrange themselves in an arch which differs in different individuals. Based on original function, the teeth have been divided into three groups: the incisors, which are used principally for cutting; the canines and premolars, which originally were used for the prehension of food and today function in a cutting capacity similar to the incisors; and the molars, which are used for grinding.
The bulk of the tooth structure is composed of dentine, which is covered by enamel on the crown and by cement on the root surface. Within the tooth is a space called the pulp cavity,the pulp connects with the body through the openings at the end of the root canals, called the apical foramina.
The roots of the teeth are set in sockets or alveoli and are held in place by tiny fibers which connect with the cement covering the root surface of the tooth and the bone lining the socket.
The complete deciduous dentition numbers twenty teeth. These consist of four incisors, two canines, and four molars in each jaw. The firs and second deciduous incisors and the canines in the upper and lower jaw have one root each. These roots diverge considerably to allow room for the permanent premolars to develop between them.
The complete permanent dentition has thirty-two teeth. These consist of four incisors, two canines, four premolars, and six molars in each jaw. The premolars are named for their position in the mouth in front of the permanent molars. The first permanent molar appears behind the second deciduous molar in the fifth to seventh year. The permanent second molars erupt in the twelfth to fourteenth year. The third molar, or wisdom tooth, as it is commonly called, may erupt any time after the sixteenth year. Third molars may be totally absent in some individuals.
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