A REVOLUTION IN DENTISTRY 



53 



they have changed their places in the jaw. Upon this elemental truth 

 is founded the art of orthodontia. Were the facts not as stated, it 

 would do no good to alter the positions of teeth, since they would not 

 retain their new positions after they had been moved into them. The 

 fact that the jaws can be widened by spreading the teeth, taken in 

 conjunction with the adaptibility of the " alveolar " process, make the 

 remarkable results of the orthodontist possible. The size, shape 

 and strength of the lower jaw, or mandible, depend in great part upon 

 the work it has to do, and furthermore, the shape of the upper jaw is 

 determined by that of the lower. The lower permanent teeth are 

 erupted first, and by their repeated impactions upon their opponents 

 in the upper jaw, aided by the constant restraining and forming action 

 of the tongue and lips gradually force the upper teeth into their proper 



After. 



Before. 



places and keep them there. Provided, that the lower jaw and the 

 tongue and lips are strong and well developed, made so by sufficient 

 chewing, especially from the years of two to six, in a child's life. If 

 the child's education in chewing, however, has been neglected, the 

 dentist can and does spread the jaw as already stated, so that it will 

 have room enough for all the teeth. In other words, orthodontia does 

 what nature would accomplish unaided were her simple laws of devel- 

 opment properly observed. 



A full set of teeth forms a beautiful arch, no stone of which should 

 be missing. The shape and span of this arch are greatly determined 

 by the size and position of the four permanent first molars, " six-year- 

 old molars," the largest and most important teeth in the head. If 

 these teeth are properly disposed in the jaws, the regulation of the 



