Cephalometric characteristics of anterior open bite in a southern Chinese population

The cephalometric characteristics of skeletal anterior open bite (AOB) in a southern Chinese population were evaluated in a group of 104 subjects with AOB and were compared with a control group of 40 subjects without AOB. The anteroposterior jaw relationship in the AOB group was Class I in 43%, Class II in 14%, and Class III in 43%. Cephalometric analysis of all subjects was completed by using 24 skeletal and 12 dentoalveolar measurements. Sexually dimorphic variables were identified and compared separately between groups with independent t tests. Two levels of significance were used, P < or = 0.05 and P < or = 0.001. Sexual dimorphism of cephalometric variables was present in both the test and the control groups, but affected more variables in the test group. Significant findings in AOB were shorter anterior cranial base, upward and forward rotation of the maxilla, increased gonial and mandibular plane angles, increased upper posterior dental height, and increased lower anterior facial height. These findings generally coincided with those for white subjects, however, there was no conclusive evidence in this study regarding the contribution of the upper anterior facial height or the posterior facial height to the AOB deformity.