The effects of maxillary protraction treatment with rapid maxillary expansion for skeletal Class III malocclusion

PURPOSE This study evaluated the effect of maxillary protraction with rapid maxillary expansion (RME) for adolescent skeletal Class Ⅲ malocclusion cases. The anatomical cranial structures were used to superimpose and establish the reference grid. METHODS Twenty cases of adolescent skeletal Class Ⅲ malocclusion treated by maxillary protraction were included as the treatment group, another 20 cases of adolescent skeletal Class Ⅲ malocclusion without treatment were used as the control group. Cephalometric analysis according to the reference grid superimposed by the anatomical cranial structures was carried out before and after treatment. The data were statistically analyzed using SPSS 13.0 software package. RESULTS There was significant increase in maxillary length（Ptm-ANS）(P<0.01).SNA and the maxillary position (A-N) differences were statistically significant (P<0.05) while there was no significant change in maxillary sagittal position (S-Ptm). CONCLUSIONS It is a feasible approach to assess changes of the hard tissue after orthopedic therapy using the reference grid superimposed by anatomical cranial structures．.