Objectives To study the changes of hard tissue before and after orthodontic treatment for Angle's class Ⅲ malocclusion adolescence patient with maxillary front traction. Methods 20 cases of Angle's class Ⅲ malocclusion adolescence patients were treated by front traction in maxilla, while there were 20 cases of Angle's class Ⅰ malocclusion adolescence patients as the control group. Cephalometric a-nalysis was carried out before and after the treatment. Data were analyzed by SPSS11.0 system using paired t-test. Results There were significant increases in the length, anteroposterior diameter and thick-ness of maxillary sinus (P<0.05), while there was no significant differences in the site and central point of maxillary sinus(P>0.05). Conclusions It is a effective approach to change the hard tissue after ortho-dontic treatment for Angle's class Ⅲ malocclusion adolescence patient with front traction in maxillary area.

[Objectives]This study was designed to evaluate the treatment effects of a new movable molardistalization appliance for distal movement of maxillary first molars on Angle's Class Ⅲ malocclusion adolescence patients with the second premolar crowded.[Methods]Sixteen patients were treated by a new movable molardistalization appliance.Cephalometric analysis and model measurement was carried out before and after the treatment.Data were analyzed by paired t-test.[Results]The molars were distalized 5 mm during an average time of 3.8 months.There were significant increases in the Angle SNA and A-NPg(P ＜0.05).[Conclusion]it was a effective way to get space and improve patient's profiles on Angle's Class Ⅲ malocclusion adolescence patients with the second premolar crowded by the new movable molardistalization appliance.It was also conducive to patient's oral hygiene.