Preliminary Clinical Study of Reverse Twinblock on Correcting Skeletal Class III Malocclusion in Mixed Dentition

Objective:To investigate the hard tissue changes of functional class Ⅲ malocclusion corrected with reverse Twinblock.Method:Eight cases of Class Ⅲ functional malocclusion in mixed dentition treated with reverse twinblock,were selected.Lateral cephalometric radiographs taken at the begining and end of the treatment were assessed.Result:After treatment,the average overjet increased 6.66mm,the average ANB angle increased 2.68°,the average length of PNS-A'increased 1.63mm,the average length of Ar-Go increased 5.16mm,the NSAr angle increased 0.98°,and the upper incisor proclined,but the change of the length of mandibular body,the mandibular plane angle,and the ratio of posterior and anterior facial height,had no statistical meaning.Conclusion:During the treatment of skeletal Class Ⅲ malocclusion in mixed dentition,the reverse Twinblock could procline the upper incisor,accelerated the development of maxillary and mandibular ramus,and restrained the development of mandibular body.A randomly allocated prospective study was required to fully evaluate the bone efficacy of this appliance.