## 4 Discussion
This inconsistency may be due to the differences in the position of the MARPE jackscrew, length of the anchor screws, age of the study participants, etc. [20; 21]. In this study, the mean expansion in the ANS and PNS regions was 4.41 \(\pm\) 1.34 mm and 3.55 \(\pm\) 0.98 mm, respectively. The percentage ratio of posterior to anterior expansion was approximately 80%. Compared to the conventional RPE without skeletal anchorage reinforcement, which demonstrated expansion in the anterior regionby 2.42 to 4 mm while the expansion in the posterior region was 0.84 to 2.88 mm, the percentage of posterior suture opening is still larger with the MARPE in this study [22]. [PERSON] et al. have reported that MARPE can alter the zygomaticomaxillary complex by rotating the zygomatic process [8]. Their study demonstrated that the extent of skeletal changes in the craniofacial complex after MARPE was significantly greater than that after conventional RPE. Similarly, we attempted to determine any change in the inter-zygomaticomaxillary suture distance for maxillary expansion which may cause changes in this distance. The statistical results indicated a significant increase in the zygomaticomaxillary suture distance, with a mean of 1.49-mm increase. All the participants in this study demonstrated an increase in this measurement at T2 compared to that at T1. Thus, the expanding ability of MARPE reaches the zygoma. However, many of the participants were growing adolescents, and establishing control groups with the same age range is necessary to fully confirm this expansion effect in the zygomaticomaxillary suture. Although we cannot fully rule out the possibility of a growing effect on the inter-zygomaticomaxillary suture distance, the time differences between T1 and T2 were relatively short (4.4 \(\pm\) 2.1 months), and little growth effect was expected. Increased nasal airway dimensions after palatal expansion have been reported in previous studies [23; 24]. The current study results demonstrated increased dimensions of the nasal width not only in the lower part, which is structurally near the palate, but also in the upper nasal width, which was significantly increased. These results indirectly support the hypothesis that the nasal airway volume increases with MARPE treatment. We also evaluated changes in nasal septum deviation after palatal expansion. Nasal septal deviation is associated with nasal obstruction, which leads to nasal breathing difficulties [25]. Therefore, relieving nasal septum deviation after MARPE would be another explanation for better nasal breathing after palatal expansion as reported in the literature [23; 26; 27]. However, few studies have been conducted on this issue, and the results are conflicting [28; 29]. Meanwhile, no significant change in the nasal septum deviation angle measured before and after palatal expansion was observed in this study, indicating that the nasal septum deviation did not improve after MARPE expansion. However, this measurement represented only the coronal plane and did not evaluate the horizontal plane. Furthermore, this study did not evaluate long-term changes. Further investigation is required to address this issue.