A text-book of dental histology and embryology, including laboratory directions . ction is to give some conception of the direction ofgrowth in the development of the bones of the face andthe way in which the changes are brought about. This can best be done by studying the series of skullsfrom childhood to old age, in which the outer cortical platehas been removed so as to show the developing teeth in theircrypts and the relation of the forming teeth to those alreadyin occlusion (Figs. 300 to 314). At birth all of the teethexcept the second and third molars have begun to develop,and their toot
A text-book of dental histology and embryology, including laboratory directions . ction is to give some conception of the direction ofgrowth in the development of the bones of the face andthe way in which the changes are brought about. This can best be done by studying the series of skullsfrom childhood to old age, in which the outer cortical platehas been removed so as to show the developing teeth in theircrypts and the relation of the forming teeth to those alreadyin occlusion (Figs. 300 to 314). At birth all of the teethexcept the second and third molars have begun to develop,and their tooth germs are lying embedded in the cancelloussubstance of the maxilla. In the upper jaw they occupyalmost all of the space to the floor of the nose and orbit,and there is little if any indication of the maxillary sinus(Fig. 300). Each tooth germ is enclosed in a separatecrypt, the wall of which is formed by a cribriform walls of the crypts are braced against each other andthe cortical plates of the maxillae by spicules of cancellous THE GROWTH OF THE JAWS 391 Fig. 300. Maxillae at about eight months after birth, showing the unerupted tooth. 392 THE TEETH AND DEVELOPMENT OF THE FACE bone surrounding medullary spaces. As the tooth developswithin its crypt, pressure is exerted and the crypt wall ispushed backward through the cancellous bone. Growth Force.—The force exerted by the growing tooth isthe result of the multiplication of cells in the tooth germ,and is exactly comparable to the forces exerted by multi-plication of cells in any position. For instance, the forceexerted by the multiplication of the cells in the rootlet of a Fig. 302
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
