STUDIES ON THE AMOUNTS OF DEVELOPING PERMANENT TOOTH GERM

영구치(永久齒) 치배형함(齒胚形咸)에 관(關)한 연구(硏究)

Of 633 children, 334 in male and 299 in female, whose ages ranged from 3 to 13 years old, the amounts of development of teeth germ were observed according to ages with oblique lateral cephalogram to study the developing state of teeth germ of mandibular premolars. The results were as followings; 1. The time of actively develop:ng tooth germ was observed about 10 years old both in male and in female. 2. The increasing rate of development of tooth germ a year was higher in female than in male at mandibular 1st premolar and in male than in female at mandibular 2nd premolar. 3. Age of complete tooth germ development was earlier in female than in male at mandibular 1st and 2nd premolars.