Abstract: Objective：To evaluate the effect of midpalatal mini-implant anchorage system in fixed appliance treatment. Methods:In this study, 14 adolescents who had skeletal class Ⅰ or Ⅱ malocclusions were involved. Maximal anchorage was required during orthodontic treatment. Maxillary first premolars of the selected individuals were extracted and the individuals were treated by fixed appliance. One mini-implant was inserted in the midpalatal suture region and a transpalatal arch (TPA) made of 0.019  inch×0.022  inch(1  inch=2.54 cm) stainless steel was adhered to the mini-implant and upper first molars. Cephalometric radiographs taken after mini-implants inserted (T0) and before mini-implants removing (T1) were traced and measured. SN-7 plane and PP plane were used as reference planes. Student’s t-test was used.Results: The successful rate of midpalatal mini-implant was 73.9%. All the items measured were found with no significant difference  between the two groups.Conclusion: This mini-implant system as orthodontic anchorage in midpalatal region can be an alternative method of maximal anchorage during orthodontic treatment.

Key words: Orthodontic anchorage procedures, Palate, Orthodontics, Cephalometry