Morphometric analysis of the transverse dentoskeletal features of class II malocclusion in the mixed dentition.

The aim of the present study was to evaluate the dentoskeletal features of Class II malocclusion in the transverse plane by means of a morphometric analysis (thin-plate spline analysis [TPS]) applied to posteroanterior cephalograms. A sample of 49 subjects (24 males, 25 females; mean age 7 years, 9 +/- 5 months) with Class II Division 1 malocclusion was compared with a control group of 50 subjects (17 males, 33 females; mean age 8 years, 4 +/- 3 months) with Class I occlusion. Subjects of both groups were in the mixed dentition and had no history of orthodontic treatment. Average craniofacial configurations were subjected to TPS analysis to compare the differences in shape between the two groups. The results of the present study showed that subjects with Class II malocclusion exhibited significant shape differences in craniofacial configuration in the frontal plane when compared with subjects with normal occlusion; these differences mainly consisted of a contraction of the maxilla at both the skeletal and the dentoalveolar levels and a narrowing of the base of the nose. The reduction in maxillary dentoskeletal width was associated with an increase in the vertical height of the maxilla.