Effect Of Modified Maxillary Protraction On Skeletal Class ⅲ Malocclusion

To measure the changes of facial-related hard tissues before and after modified maxillary protraction in patients with skeletal class Ⅲ malocclusion at post-peak growth period and analyze the efficacy of the protraction. A total of 31 cases with skeletal class Ⅲ malocclusion at post-peak growth period who visited the Department of Orthodontics from 2017 to 2023 were selected, including 19 males and 12 females, aged 12-15 years old. Treatment was performed using a modified pad intraoral appliance combined with extraoral double-rod maxillary anterior distractor. The average treatment course was 8.4 months. Before and after treatment, lateral cephalometric radiographs were taken to measure and analyze the changes of facial bone and dental indices. Before and after modified maxillary protraction treatment, the sagittal position indices of maxilla, SNA, ss/OLP, Or/OLP and Ptm/OLP increased by 2.66°±1.29°, (3.70±1.95) mm, (1.44±1.94) mm, and (0.83±1.49) mm respectively (P<0.01). The inclination of upper anterior teeth (U1-SN) increased on average by 1.16°. The inclination of lower anterior teeth (IMPA) decreased by 0.75°±4.83° (P>0.05). The application of modified pad intraoral appliance combined with extraoral double-rod maxillary anterior distractor can effectively promote maxillary advancement of patients with skeletal class Ⅲ malocclusion at post-peak growth period, and control the lip inclination of upper anterior teeth and tongue inclination of lower anterior teeth well.