A Study On Transpalatal Arch For Reinforcing Anchorage In Orthodontic Treatment

【Objective】: The purpose of this study is to evaluate the mechanism and effect of transpalatal arch on reinforcing anchorage .【Methods】: The samples selected in this investigation consisted of 42 cases , who all satisfied the trial criteria. 28 cases were allocated in the test group, while 14 in control group. All detailed records must be conducted before treatment including good quality dental casts, cephalometric roentgenograms, panoramic, as well as facial photos. Furthermore, four first premolars were extracted and standard edgewise appliance were applied. Transpalatal arch was chosen in test group to reinforce anchorage of upper first molars , while no special anchorage was applied into control group. At three stage T1,T2,T3, dental casts and cephalometric roentgenograms were taken and analyzed respectively.【Results】: 1. Sagittal plane: at the stage T3 for test group, upper incisors retracted and upper and lower first molars both apparently moved forward, with more displacement of lower molar. By comparison , the anchorage molars showed more forward movement in control group than test group. 2. Vertical plane : occlusal displacement of upper molars was not examined in test group at the stage T3 , while upper molars in control group tended to extrude compared to test group, with clockwise rotation of mandibular plane. 3. Transverse plane: there lacked evident change in upper molar width for test group at the stage T3, but control group displayed apparent decrement in upper posterior arch width at stage T1 ,T2.【Conclusion】: Transpalatal arch can play an important role in anchorage reinforcement for those patients with four premolars extracted.