Abstract
The dental arch and the size of tooth crown of the siblings apparently resemble one another in their form and measurement values. How about overjet and overbite? The materials for this study are the plaster casts of upper and lower jaws obtained from the inhibitants in Kami-Ina district, Nagano prefecture. On these plaster casts overjet and overbite were measured. The degree of resemblance among siblings was evaluated by means of correlation coefficient and relative deviation (deviation ratio). The authors compared the degree of resemblance of the siblings groups with that of the free group consisting of members taken at random out of each group. The following is the summry of this research:
The degree of resemblance of overjet and -bite is more remarkable between the siblings than between the free group.
In general, the degree of resemblance is only slightly stronger between the siblings of the same sex than between those of different sex.
No definite difference between overjet and-bite, and size of tooth crown is observed in the degree of resemblance.
