Multivariate analysis of tooth crown morphology in Japanese-American F1 hybrids

Abstract

Mesiodistal crown diameters of I1 through M1 and six non-metric crown traits in permanent dentition of Japanese-American F1 hybrids were compared with those of the parental populations. The hybrids were born of Japanese females and American males, both Caucasians and American Blacks, after World War II and brought up at Elizabeth Saunders Home in Kanagawa Prefecture, Japan. The comparisons were undertaken by means of multivariate analysis methods such as principal component analysis, distance and similarity coefficients and multidimensional scaling. The F1 hybrids generally occupy an intermediate position of the two parental populations, and this is particularly evident in size component of the crown measurements and in distance analysis of frequencies of the non-metric crown traits. The shape component of the crown measurements, however, not necessarily follows such a rule and suggests a more complicated gene control than in the case of the size component. Also, each measurement and frequency of non-metric trait of tooth crowns in F1 hybrids is not uniformly at the middle position between their parental populations but this is true when they are analyzed as multivariables.