ERUPTION OF THE PERMANENT INCISORS. 



167 



Three Years, Three Months. — Between three years and 

 three and one-half years the second intermediate have replaced 

 the milk-teeth. (Fig. 164.) 



Fig. 164. 

 Three years, six months, a, external face. 6, internal face. 



In this mouth the second intermediate teeth have reached 

 the level of the incisive arch and their enamel has commenced 

 to be used. 



Four Years. — Between three years and nine months and 

 four years and six months the corner teeth are completely 

 through the gums and the mouth is complete. (Fig. 165.) 



