Craniofacial Growth and Development of 16 Class II Bolton Females

The invention of the Broadbent-Bolton cephalometer in 1925 made possible the collection of three-dimensional (3d) data from biorthogonal plain film head radiographs. Objective: To compare longitudinal changes in the shape and size of craniofacial structures between 16 untreated Class II, Division 1 females and 16 untreated Class I Bolton females. Methods: Procrustes analyses were used to compare differences in a constellation of thirty 3d cephalometric landmarks. The same methods were also used to analyze changes of 4 subsets of landmarks (Maxilla, Mandible, Midface and Cranial Vault). Comparisons included shape and size differences between adjacent age groups at ages 6, 11, and 15 in the class II sample as well as between the class I and class II samples at each age. Results: Overall, the craniofacial complex undergoes continuous shape change from ages 6-15 in both samples. Within the Class II sample, the smallest contribution to craniofacial shape change was seen for the mandibular landmarks between ages 6-11. Compared to the Class I sample, the Class II sample exhibits (1) a longer facial pattern, (2) the smallest mandibular shape difference at age 6, and the largest at age 15, and (3) maxillary landmarks more protrusive at all age periods compared to the class I sample. The Class II also had the largest change in size during ages 11-15 (6.5%), while for the Class I ages 6-11 showed the greatest size change (10.5%). Conclusions: In this sample, there were significant shape differences during the growth and development between Class II and Class I female subjects.