Treatment effects of combined bionator-headgear appliance and high-pull headgear in skeletal Class II cases : Comparison between twins

Abstract

High-pull headgear and the combined activator-headgear appliance are commonly used for skeletal class II, long-face type malocclusion. The purpose of this study was to compare the treatment effects of the high-pull headgear and the combined bionator-headgear appliance for growing patients with skeletal class II, long-face malocclusion, using cephalometric analysis of twins. The twins were 7years, 6months of age and diagnosed as skeletal class II, long-face. The elder brother was treated with the combined bionator-headgear appliance for 1 year and 11 months. The younger brother was treated with high-pull headgear for 2 years and 5 months. Comparing the cephalograms obtained from before and after treatment indicated the following. Both cases showed the inhibition of anterior growth of the maxillary. The mandibular plane angle decreased and the ratio of upper to lower facial height was mostly maintained in the two cases. Upper molar eruption was inhibited in the two cases and the combined bionator-headgear appliance inhibited eruption of the lower molar. ANB angle was improved 1.9° in the high-pull headgear case and 2.0° in the combined bionator-headgear appliance case due to the restriction of maxillary growth, the clockwise mandibular rotation, and the increase of mandibular length. No differences were found in the increment of the mandibular length. These results indicated that both appliances are very effective for correcting skeletal class II, long-face malocclusions in the mixed dentition. There are little differences between treatment effects except that the combined bionator-headgear appliance inhibited the lower molar eruption more than the high-pull headgear.