ERUPTION OF THE PERMANENT TEETH 125 



THE TEETH 



The consideration of the teeth will be taken up under the 

 following headings: 1. The eruption of the permanent teeth; 

 2. The alternation of growth in stature and eruption of the per- 

 manent teeth; 3. The eruption of the individual permanent 

 teeth; 4. Review of the literature and discussion. 



The youngest childi'en whose teeth I examined were five years 

 old, and at that age all the temporary teeth have erupted, there- 

 fore the time of the eruption of the temporary teeth cannot be 

 given. The decay of the temporary teeth occurs partly after 

 the age of five years, and this will be considered, in addition to 

 the eruption and decay of the permanent teeth. 



The eruption of the pervianent teeth 



This is determined by taking the average number of teeth 

 erupted or erupting at each age, as well as the 'median,' the 'mode' 

 and the 'extremes,' after which the periods of acceleration and 

 retardation in the eruption of the permanent teeth will be given. 



The eruption of the permanent teeth begins about the age of 5 

 years, slightly earlier among the girls and slightly later among 

 the boys of the German and American groups, but considerably 

 earlier than this among the Filipinos of both sexes. The Ger- 

 mans and Americans of both sexes have almost exactly the same 

 number of permanent teeth at the ages of 6, 7 and 8 years, after 

 which the girls have a greater number of teeth than the boys until 

 the age of 15 is reached, when the number of teeth in the two 

 sexes is again about the same. 



The girls of each group are more precocious in the eruption of 

 the permanent teeth than the boys, they have a greater number 

 of permanent teeth at each age, and the difference is greatest 

 between the ages of 8 and 15 years, for at the age of 11 years the 

 American girls have an average of 21.3 permanent teeth present, 

 and the American boys have an average of only 17.3. The differ- 

 ence between the German boys and girls at this age is not so 

 great, and they have only 16.7 and 19.5 teeth present for the boys 

 and girls respectively. The difference between the Filipino boys 



