Study Of Mandibuler Opening And Protrusion Movement Trajectory In Skeletal Anterior Reverse Bite Malocclusion In Early Stage Of Mixed Dentition

Skeletal anterior reverse bite is one of the most frequent malocclusions happened in Asia. Whether to give early treatment to that kind of malocclusion is still a question vexed by orthodontists. In this study, we use cephalometric analysis and a new kind mandibular movement analysis system - ACRUSdigma system, which use the kinematic center that can represent the translation and rotation of the condylar and insicial point as refrence point to compare the diffirence of the empty opening and protrusion mandibular movement trajectory of 35 skeletal anterior reverse bite maloccusions and 19 nomal occlusions in early stage of mixed dentition. And we also compare the diffirence of the mandibular empty opening and protrusion movement trajectory of the 30 skeletal anterior reverse bite maloccusions which accept protraction facemask treatment as the early treatment at different stages, which is before treatment, when the anterior reverse bite was relieved, and when the early treatment was over. 1. Cephalometric result1. 1 There are some diffirence between the skeletal anteior reverse bite and the normal occlusion. For example, in the the skeletal anteior reverse bite group, the SNA angle, the Tl-Me/SN angle, the Ans-ME, the Co-A, the wits analysis are lower and the SNB angle, the Ans-Pns/SN angle, the OL/SN angle, the lii-Iia/Tl-ME angle are greaterH 4 M ft 90 Hthan those hi the normal occlusion group. 1 . 2 There are some markedly changes at the end of the early treatment. For example, the SNA angle, the Tj-Me/SN angle, the Ans-ME, the Co-A, the wits analysis are increase and the SNB angle, the Ans-Pns/SN angle, the OL/SN angle, the Iii-Iia/TrME angle are reduce.2. Mandibular movement trajectory2. IFor the kinematic center, the typical trajectory of the skeletal anterior reverse bite maloccusions moved more horizontally than that of the normal subject in the entire empty opening movement on the sagittal plane and the sagittal angle of the kinematic center is significant smaller than that of the normal subject before treatment. The sagittal angle of the kinematic center ithe sagittal angle of the kinematic center increased when the anterior reverse bite is relieved, and the sagittal angle of the kinematic center ithe sagittal angle of the kinematic center increased to normal when the early treatment is over. For the incisal point, the typical trajectory of the skeletal anterior reverse bite maloccusions went down almost vertically from the ICP, on the other hand the path of the normal occlusion subject moved to a more anterior position from the ICP and the sagittal angle of the skeletal anterior reverse bite maloccusions is differ from that of the normal occlusion subject normal occlusion subject. The path and the sagittal angle were changed when the anterior reverse bite is relieved. The path and the sagittal angle were changed to normal at the end of the treatment.2. 2 For the kinematic center, the typical trajectory of of the skeletal anterior reverse bite maloccusions moved more horizontally than that the normal subject in the entire empty protrusion movement on the sagittal plane and the sagittal angle of the kinematic center isH5 M & 90 3Csignificant smaller than that of the normal subject before treatment. The sagittal angle of the kinematic center ithe sagittal angle of the kinematic center increased at initial of the movement when the anterior reverse bite is relieved, and the sagittal angle of the kinematic center ithe sagittal angle of the kinematic center increased to normal when the early treatment is over. For the incisal point, the typical trajectory of of the skeletal anterior reverse bite maloccusions moved more horizontally than that the normal subjectand the sagittal angle of the skeletal anterior reverse bite maloccusions is differ from that of the normal occlusion subject normal occlusion subject. The path and the sagittal angle were changed when the anterior reverse bite is relieved. The path and the sagittal angle were changed to normal at the end of...