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 sub jects with AOB and were compared with a control group of 40 subjects w ithout AOB. The anteroposterior jaw relationship in the AOB group was Class I in 43%, Class II in 14%, and Class III in 43%. Cephalometric a nalysis of all subjects was completed by using 24 skeletal and 12 dent oalveolar measurements. Sexually dimorphic variables were identified a nd compared separately between groups with independent t tests. Two le vels of significance were used, P less than or equal to 0.05 and P les s than or equal to 0.001. Sexual dimorphism of cephalometric variables was present in both the test and the control groups, but affected mor e variables in the test group. Significant findings in AOB were shorte r anterior cranial base, upward and forward rotation of the maxilla, i ncreased genial and mandibular plane angles, increased upper posterior dental height, and increased lower anterior facial height. These find ings generally coincided with those for white subjects, however, there was no conclusive evidence in this study regarding the contribution o f the upper anterior facial height or the posterior facial height to t he AOB deformity.