Abstract: Objective: To investigate the efficacy of miniscrew-assisted rapid maxillary expansion combined with anterior traction in treating horizontal and sagittal underdevelopment of the maxilla. Methods: A total of 20 patients [11 males and 9 females, age (11.7±1.0) years] with maxillary horizontal and sagittal hypoplasia were selected. CBCT was collected before treatment, at the end of arch expansion, at the end of anterior extension, and at the end of treatment. The indicators reflecting jaw horizontal orientation, sagittal orientation, and soft tissue profile were measured at each treatment stage, and the changes of jaw bone and soft tissue profile were analyzed and explored. Results: The width of maxillary basal bone and basal bone arch increased significantly after treatment. There was no significant difference in the width of mandibular basal arch before and after treatment. A-Nperp, A-Sperp, Wits, SNA°, and FH-NA° increased gradually during treatment. The subnasal point-zero meridian became larger, and the premental point-zero meridian, the lower lip -TVL, and the premental point -TVL became smaller. Conclusion: Miniscrew-assisted rapid maxillary expansion combined with anterior traction can effectively treat maxillary horizontal and sagittal hypoplasia, and the side appearance was improved.

Key words: miniscrew-assisted rapid maxillary expansion, anterior traction, insufficient development of the maxilla