Skeletal Patterns Variation In Adolescent Patients With Normal Trend Growth Pattern After Orthodontic Extraction Treatment

Objective:To further exposit changes in extraction treatments and to provide the reference for orthodontic extraction treatment's effects to Skeletal patterns,by measuring and analysing skeletal measurements through analyzing the lateral cephalograms of patients before and after orthodontic extraction treatments.Methods:20 class ? normal trend growth pattern patients with or without extraction were chosen respectively.4occlusal plane index,4maxillary index,5mandibular index,2face height index and 2dental index were measured.Paired t-test and rank sum test were used to explore skeletal patterns' change after orthodontic extraction treatmentResults:1.Occlusal plane index: posterior occlusal plane in both groups showed statistically significant decreases.Anterior occlusal plane showed statistically increases in extraction group.Conventional occlusal plane's change in both groups had no statistical significance.2.Maxillary index: maxillary index before and after treatments in both groups had no statistical significance.3.Mandibular index: changes of length of the mandible and mandibular condyle in both groups had statistical significance.Face height's change in both groups had statistical significance.Mandibular plane in nonextraction group showed statistically significant increases,which in extraction group had no statistical significance.4.Dntal index: molar after treaments in both groups showed statistically significant antedisplace-ment.5.Angle of mandibular plane after treaments in extraction group showed statistically significant decreases,mandible after treaments in extraction group had anti-clockwise rotation.6.Correlation analysis: there was correlation between molar antedisplacement and mandible rotation.Conclusions:1.By aligning and leveling with straight wire appliment,occlusal plane become flat,molar teeth have physiologic anchorage loss,which shows the importance of preparation for physiologic anchorage.2.Maxilla development basically complete during puberty,mandible growth has potential,changes of physiologic facial types can be predicted before orthodontic treatment.3.Orthodontic extraction treatments produce straitness and short of dental arch and anti-clockwise rotation of mandible,which affect facial types.4.There is correlation between molar antedisplacement and mandible rotation.Because of wedge effect,the further first molar moves forward,the larger mandible anti-clockwise rotate.The circumstance is beneficial to high angle patients.There is necessary to reinforce anchorage and control hight of molar for low angle patients.