Cephalometric comparisons of the dentofacial relationships of two adolescent populations from Iowa and Northern Mexico

Abstract The purpose of this study is to develop cephalometric standards for North Mexican male and female adolescents. The subjects evaluated in the study included 36 North Mexican boys with a mean age of 12.8 years and 45 North Mexican girls with a mean age of 13.0 years. The Iowa sample included 20 boys and 15 girls of similar age who were participants in the longitudinal facial growth study at the University of Iowa. Basic descriptive statistics are presented on 26 cephalometric parameters arranged in five categories: (1) skeletal angular relationships, (2) skeletal linear relationships, (3) dental angular relationships, (4) dental linear relationships, and (5) soft-tissue profile relationships. The general linear models procedure—analysis of variance—was used for comparisons between the two populations. F values were calculated for the overall group comparisons and indicated the presence of statistically significant differences between the four subgroups examined, namely, Iowa boys and girls and North Mexican boys and girls. Significant differences between boys and girls within each population were found in the skeletal linear parameters of both the anterior and posterior face heights. Furthermore, in the North Mexican population, the Holdaway soft-tissue angle was significantly larger in boys than in girls, indicating a more convex soft-tissue profile for boys at this age. When comparisons were made between the two populations, it was of interest to note the absence of any significant differences between the North Mexican and Iowa boys. But when the North Mexican girls were compared to the Iowa girls, the SNB and SNPog angles, as well as the ratio of posterior face heights, were significantly larger for the North Mexican girls. This indicates that, on the average, the adolescent North Mexican girl has a relatively more protrusive mandible than the adolescent Iowa girl. The findings presented in this study provide the orthodontist and others interested in this field with cephalometric standards applicable to both the North Mexican adolescent population and individuals in the United States whose origins are from the same geographic area of Mexico.