. First aid in illness and injury; . and are adapted for cutting food, whence they are called incisors: they have but a single root. On either side of the incisors are the canines, so called from their resemblance to those of the dog. They are spear-shaped, and adapted for rending food, — an evidence of the carnivorous phase of man: they alsohave but one root. Those in theupper jaw are vulgarly known as eye teeth; those in the lowerjaw, as stomach teeth. On eithersides of these are two bicuspids orpremolars, generally with a singleroot, and on either side of themare two molars or grinders, wit
. First aid in illness and injury; . and are adapted for cutting food, whence they are called incisors: they have but a single root. On either side of the incisors are the canines, so called from their resemblance to those of the dog. They are spear-shaped, and adapted for rending food, — an evidence of the carnivorous phase of man: they alsohave but one root. Those in theupper jaw are vulgarly known as eye teeth; those in the lowerjaw, as stomach teeth. On eithersides of these are two bicuspids orpremolars, generally with a singleroot, and on either side of themare two molars or grinders, withtwo or three roots. These teethhave a more or less cubical crown,the masticating surface of which isridged to admit of the triturationor grinding of the food. The last molars are known as the wisdom teeth. The molars represent the herbivorous phase of man. At birth, the teeth have not yet appeared, and it is not until from the fourth to the seventh month that the lower central incisors push their Fig. 7. — Structure ofa Fig. 8. —The teeth. 14 CONSTRUCTION OF THE HUMAN MACHINE way through the gums, and are followed during the first two and a halfyears of life, in the order given, by the other incisors,, the first molars,the canines, and the second molars. The eruption of the teeth throughthe gums — teething — is commonly attended by more or less dis-turbance of the system, varying from a slight indigestion to violent con-vulsions. Where the trouble is sufficient to demand interference, aslight cut in the gum over the coming tooth will relieve it. During the years following their appearance, in sacs at the roots ofthe deciduous teeth, a second set of teeth has been forming, which, asthey grow, press upon the deciduous roots until they cause their entireabsorption, leaving only the crowns, which are finally cast off, leavingroom for the new permanent teeth. The first permanent teeth to appearare the first molars at the end of the sixth year, followed during then
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Keywords: ., bookcentury1800, bookdecade1890, bookpubli, booksubjectphysiology
