Three-dimensional evaluation of changes observed in the midface regionafter maxillary skeletal expander application: a retrospective study

Three-dimensional Evaluation of Changes Observed in the Midface Region After Maxillary Skeletal Expander Application: A Retrospective Study The aim of this thesis study was to investigate the skeletal and dental effects of the Maxillary Skeletal Expander 2 (MSE 2) appliance in individuals between the ages of 12-18 years. 18 patients with unilateral or bilateral posterior crossbite who were treated at Ankara Yıldırım Beyazıt University Faculty of Dentistry Department of Orthodontics between 2022 and 2023 were included in the study. Pre- and post expansion CBCT images were used to investigated the effects of the MSE 2 appliance. The CBCT images were exported and saved in medical digital imaging and communication files (DICOM) format. Subsequently, these CBCT images were superimposed on the anatomical structures of the entire anterior skull base by automatic processing in matching voxel grayscale patterns using OnDemand 3D software (Cybermed Inc., Seoul, Korea). After the MSE 2 application, seperation of the maxillary sutures in the midfacial region and an increase in width in the midpalatal suture, maxilla and midfacial region were observed. A parallel shaped seperation was observed in the midpalatal suture. It was identified that the maxilla moved forward and downward, rotational movements occurred in the maxilla and the center of rotation was slightly above the frontozygomatic suture. During the width increase, dental movements also occurred and buccal tipping was detected in the supported first molar teeth. During the expansion, it was determined that the center of resistance was the lateral-medial pterygoid process region. As a result of our study, it can be said that the MSE 2 appliance creates significant changes in the midface region with its appliance design and different force transmission. Although it has certain advantages over conventional rapid maxillary expansion appliances, it has been determined that side effects seen in conventional rapid maxillary expansion appliances can be observed.