## 4 Discussion
### Overall Skeletal and Dental Changes (T1-T3)  
The present findings showed that the amounts of maxillary protraction and of improvements in the maxillomandibular anteriorposterior relationship were greater after maxillary protraction using a miniscrew- rather than a tooth-anchored device, even after growth peaked (T-A vs. M-A): SNA, +2.65\({}^{\circ}\) vs. +3.29\({}^{\circ}\); ANB, +0.73\({}^{\circ}\) vs. +2.51\({}^{\circ}\)\(p\) < 0.05). These results were consistent with the those of the study described above using a tooth-anchored device vs. a miniplate (SNA +2.7\({}^{\circ}\) vs. +3.9\({}^{\circ}\); ANB, +1.4\({}^{\circ}\) vs. +3.3\({}^{\circ}\); \(p\) < 0.05) [16]. In addition, even after the period of maximum growth (T3), maxillary first molar extrusion was maintained when a tooth-anchored device was used, as was the situation immediately after treatment (T2). This resulted in a large increase in the vertical dimension of the lower face (T-A vs. M-A: U6/NF, +4.56 vs. +2.60 mm; N-Me, +10.24 vs. +7.90 mm, \(p\) < 0.05). In contrast, the vertical dimension of the lower face did not significantly differ between groups treated with a tooth-anchored device and a miniplate, which was inconsistent [16]. This might be because we prevented extrusion by directly holding the maxillary first molar in an oral device, whereas the miniplate did not directly prevent such an extrusion. In addition, the difference might have occurred because the average observation period was 6.5 years, which was longer than in our study. Although there was a trend toward decreased skeletal improvement with facemask treatment during T2-T3, ANB remained within normal range in both groups, with a positive overjet at T3. This may reduce the need for orthognathic surgery in patients with Class III malocclusion, regardless of the type of intraoral device. This is consistent with a previous study by [PERSON] et al., showing that early facemask treatment reduces the need for orthognathic surgery by one-third compared to no-treatment patients [22]. This study included follow-up starting before and ending at an average of 3.9 years after treatment. We confirmed that the maxillomandibular anteriorposterior relationship can be improved even when teeth serve as anchors for maxillary traction. However, better improvement was achieved by bone anchoring, and first molar extrusion could not be avoided. This dentoalveolar effect may have increased the anterior facial vertical dimension after treatment. In light of these, maxillary protraction using a miniscrew-anchored device that connects and fixes the maxillary first molar to the palatal area is more effective for pediatric patients with skeletal Class III malocclusions and a hyperdivergent skeletal pattern during long-term follow-up. This indicates favorable stability. The design of this study has some limitations. Because this is a retrospective study, experimenter bias may have been involved. In actual clinical practice, when selecting a tooth- or bone-anchored device, orthodontist's bias may be reflected due to the patient's cooperation in the process of installing the miniscrew under infiltration anesthesia. Considering these factors, it is unfortunate that the age at treatment initiation (T1) was different between the two groups in this study. In addition, although this study has the advantage of an average follow-up period of 37 months, it is difficult to determine whether mandibular growth is complete in all patients when considering CVMS. Therefore, it is difficult to accurately determine the skeletal and dental difference in facemask treatment between the two groups over a longer period of time until growth is complete. Future studies could support the facemask treatments in growing patients with maxillary deficiency if a study is designed that matches patient age with bone age, CVMS, at the start of treatment, regardless of intraoral device type, and if long-term studies are conducted until mandibular growth is complete.