Treatment of Severe Skeletal Class III Malocclusion in Earlier Permanent Tooth with Straight-Wire Appliance

Objective To study the changes in the skeletal and soft tissue after the straight-wire appliance treatment for severe Angle's class Ⅲ malocclusion in earlier permanent dentition.Methods Eleven patients with severe skeletal class Ⅲ malocclusion(5 male,6 female) were all treated with straight-wire appliance.Lateral cephalometric films taken before and after the treatment were analyzed using the Pancherz analysis and traditional cephalometric anlaysis.The arithmetic mean and standard deviation were calculated for each variable and the statistic significance was evaluated by paired t-test.Results ANB angle was significantly increased(P0.05),but the value remained negative and class Ⅰ facial form was not achieved.L1-MP angle was decreased by 6.62° on average(P0.05) and normal anterior overjet and overbite were achieved through lingual inclination of lower incisors.Ls-Sn-SN and Sn-N'-Si angles were decreased(P0.05).Distance from Li to E line was decreased by 1.85 mm on average and soft tissue profile was improved dramatically.Conclusion Skeletal class Ⅲ malocclusion with permanent dentition can be successfully treated with straight-wire appliance and soft tissue profile can be improved.