Objective    To observe the clinical effects of transmission straight wire appliance on the treatment of AngleⅡ1 malocclusion and explore its mechanism.     Methods    Thirteen AngleⅡ1 malocclusion patients (6 males and 7 females) were treated with the appliance by extracting 4 first premolars or 2 first maxillary premolars. The results of cephalometric measurements before and after treatment were statistically analyzed.     Results    The average treatment time of 13 cases was 15.6 months. The overbite’s treatment cost 4.2 months averagely. Overbite

overjet and molar relationship were turned to normal (only one adult case had complete distal in the molar relationship by extracting 2 first maxillary premolar) and lateral appearances were improved after treatment. The results of cephalometric analysis showed that the changes of SNB

ANB

U1-NA angle

L1-NB angle

U1-LI angle

U1-NA length

L1-NB length

L6-MP length

L1C-MP length

  overbite

and overjet were of high statistical significance (P0.01) except for SNA

MP-SN angle

U6-PP length and U1C-PP length (P0.05).     Conclusion    Transmission straight wire appliance can quickly and efficiently correct AngleⅡ1 malocclusion. 