ObjectiveTo compare the differences of the molar anchorage loss and the changes of the maxillary incisors position among the extraction orthodontic patients treated by self-ligating brackets(SLBs)and conventional brackets(CBs)in order to evaluate the different clinical efficiency.MethodsFifty-two cases requiring extraction of 4 first premolars were divided into two groups according to the brackets ligation type.The traditional ligation bracket group(CB group)had 25 patients and the self-ligating bracket group(SLB group)contained 27 patients.Before and after treatment, lateral cephalograms were traced and analyzed to obtain the sagittal and vertical changes of the maxillary first molar and central incisor.Statistical comparisons were performed with Student’s t-tests.ResultsBefore and after treatment, there was no statistically significant difference in the maxillary first moral and central incisor movement between the two groups.The mean sagittal change of the maxillary first molar was( 2.90±1.58)mm and(2.26±0.92)mm, respectively, in the SLB group and the CB group.The maxillary central incisor sagittal retraction in the CB group was(2.99±1.44)mm versus(3.45±1.88)mm in the SLB group. In the vertical plane, maxillary molars extruded(0.18±0.94)mm in the CB group and intruded(0.49±1.38)mm in the SLB group. The mean vertical extrusion of the upper incisor was( 0.17±1.56)mm and(0.64±1.24)mm for the CB group and SLB group, respectively.As for the inclination of the incisor, tipping was(4.76±3.93)and(4.62±2.15)in the CB group and SLB group, respectively.There was no statistically significant difference between the changes of all measurement items before and after treatment in the two groups of cases(P>0.05).ConclusionThe maxillary morals anchorage loss in sagittal and vertical plant were not influenced by the type of bracket used.There was no difference in the upper incisor movement between the CB group and SLB group.The self-ligating brackets system do not achieve better clinical results.