## 4 Discussion  
In this study, the US angle increased in the short term but decreased in the long term after MSE, which was a slightly different result than what was seen in a previous study [11] that found a significant decrease in the US angle in the short and long term. In the previous studies [3; 5; 11; 25], the authors used the US angle to evaluate NSD. On the other hand, in this study, the MS_C angle significantly increased and the LS angles significantly decreased in the long term, causing the NSD to improve. MS_C and LS angles showed greater changes than the US angle. Therefore, MS_C and LS should be considered when evaluating NSD. Additionally, in this study, NS angles were measured in the axial plane, which showed the same tendency for NSD improvement as in the coronal plane but greater NSD in the coronal plan than in the axial plane. Absolute values (lxl) of MS in the coronal plane decreased at T3-T1, which meant the NSD improved with the expansion of the maxilla, but the absolute values (lxl) of MS in axial plane were not changed at T3-T1. Therefore, vertical NSD might be more alleviated than horizontal NSD after MSE. [PERSON] et al. [3] and [PERSON] et al. [26] proposed a strong relationship between NSD and facial asymmetry. However, [PERSON] et al. [27] insisted that NSD was mainly associated with an asymmetry in the nasal floor and palatal region, not with an overall facial asymmetry. Therefore, MSE might decrease NSD, but further studies are needed to evaluate MSE effects on facial asymmetry. In this study, the vertical NS length increased in the coronal plane after MSE, which was consistent with a previous study [11] that reported a pyriform height increase. Additionally, in this study, the horizontal NS length also increased in the axial plane. These results might be due to the downward movement of LS and posterior movement of MS_A and PS, thereby affecting the NS angles and improving NSD. [PERSON] et al. [8] suggested that vertical NS length increased in the lower third, improving NSD, which was consistent with the results of this study. Therefore, increasing nasal length in the vertical and horizontal planes might be helpful to alleviate NSD and improve the nasal airway, but further studies are needed to evaluate this. In this study, LNW widths and angles on both sides increased after MSE, which was consistent with the results of previous studies [11; 13; 20; 28]. Furthermore, the dimensions were greater on the right side than on the left side, and the results that were similar to those in a previous study [3] suggested more frequent facial asymmetry towards the right side of face. In this study, LNW widths and angles had a greater increase on the left side than on the right side at T3-T1 after MSE, which had the effect of reducing nasal asymmetry. [PERSON] et al. [29] reported that nasal floor canting was highly related to NSD and facial asymmetry, and NSD headed towards the lower nasal floor side. [PERSON] et al. [25] suggested that nasal floor canting occurred in the opposite direction to NSD. These findings were consistent with those in our study. Therefore, the direction of the nasal floor canting should be considered when planning to correct facial asymmetry. The midface moved downward and forward, increasing SNA and ANB angles after MSE in other studies [18; 20; 28; 30; 31], which was consistent with our study in which ANS and LF_ANS moved forward and downward. The mandible moved downward and backward after MSE in our study, which was consistent with the results in a previous study [28] in which MAPE caused a clockwise rotation of the mandible, thereby decreasing the SNB angle and increasing anterior facial height. This information might be helpful when planning to treat camouflage skeletal Class III malocclusion with a retruded maxilla and a protruded mandible. In this study, the ANS and Mid LF_ANS deviation was found to exist in the same direction as NSD. [PERSON] et al.