1954 年 21 巻 4 号 p. 157-162
The biting forces of the lower first molars and the grasping forces were measured using they newly designed spring type gnathodynamometer and grasping force measuring appartus on 519 subjects.
Subjects were in age of 9, 10 and 15 years in male and female, 12, 13, 14 and 16 years in female and 16, 17, 21, 22 and 23 years in male.
Following results were obtained:
1. The biting forces in both sexes increase with age gradually till 15 years, but in older than them are nearly constant. The grasping forces increase also till 17 years, but in older than them are nearly constant.
2. The biting forces are nearly equal in both sides of the jowl however, the grasping force of the right hand is considerably greater than that of left hand.
These differences are approximately 10 per cent in male and 25 per cent in female.
3. Histogram of biting force are skew, because the limit of measuring powers of the apparatus is 52 kg.
The scatter of grasping force about the mean increases with age and male's is greater than female's.
4. The regression lines and correlation coefficients between biting-and grasping force are analysed on 10 years boys and girls. The regression lines for girls are significant, but are not for boys.