Date of Award



Department of Orthodontics

First Advisor

Heesoo Oh

First Committee Member

Joorok Park

Second Committee Member

Heeyeon Suh


Introduction: Skeletal expansion has been a treatment modality in orthodontics and orthopedics to correct skeletal transverse discrepancies with maxillary constriction. The utilization of microimplants in conjunction with these palatal expanders offers a higher degree of pure skeletal expansion and minimizes the dental side effects. The purpose of this study is to evaluate the changes of the hard and soft tissues of the face after skeletal expansion for orthodontics. Methods: 36 patients who had received successful expansion with a microimplant assisted rapid palatal expander were compared to their pre-expansion records. All patients received CBCTs from which a 3-D analysis configuration was created to trace hard and soft tissue landmarks of the midface and nasal cavity regions. 3 judges analyzed each set of records and the average was used to calculate the amount of expansion experienced at each anatomical region. A paired T-test and Wilcoxon signed-rank test were used for statistical comparison between time points. Results: Expansion can affect all of the midfacial hard tissues that support the overlying soft tissues. Increases in skeletal width from the Frontozygomatic suture down to the maxillary alveolar bone were all significant. The nasal cavity increased in width in all locations measured. Soft tissue changes were significant at the base of the ala suggesting a widening of the nose with expansion therapy. Conclusion: Maxillary expansion with microimplant assisted expanders can have skeletal changes throughout the entire midface and may affect the width of the nasal cavity. Soft tissue changes were less pronounced, and though a widening of the base of the nose may be expected this may not be noticed by the patient.