ERUPTION OF THE PERMANENT TEETH 



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minds us of the development of the trunk in the first month of 

 prenatal life, followed by the rapid development of the head 

 (brain). Between the arrival of the temporary teeth and the 

 second acceleration of growth in stature (2 to 5 years), the heart 

 and kidneys are apparently developing most rapidly. The 

 eruption of the first permanent teeth, followed by the third 

 acceleration of growth in stature, is related to the most rapid 

 postnatal development of the liver, stomach and intestine. The 

 third period of rapid tooth development followed by the fourth 

 period of rapid growth in stature succeeds this and precedes 

 puberty, after which the growth of the boys is retarded and the 

 growth of girls almost ceases. There is need of more detailed 



Diagram 4 The order of eruption of the permanent teeth in Europeans. 

 One side only of the mouth is represented, the left side as viewed from in front. 

 The dots represent the individual teeth, whose symbols are placed between them. 

 The order of eruption of the teeth is represented by numbers and by the lines 

 connecting the dots. ?'. incisors; c, canines; p, premolars; m, molars. 



data relating to the postnatal periods of growth in stature, in 

 the teeth, and in the other structures of the human body. Until 

 this is forthcoming there can be no final statement as to the 

 exact relations of these periods, but enough is known of both 

 prenatal and postnatal development to justify the law of alterna- 

 tion in development. 



This law is applicable to the eruption of the individual teeth. 

 No two adjacent teeth erupt at the same time except the median 

 incisors, and the lower canines and median premolars. The 

 median line represents a barrier, therefore the places filled by the 

 median incisors are ahnost like remote areas. Diagram 4 rep- 

 resents the order of eruption of the teeth on one side of the mouth 

 in the Germans and Americans. 



