## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**RME**} & \multicolumn{3}{c}{**SME**} & \multicolumn{3}{c}{**Control**} & \multicolumn{3}{c}{**ANOVA**} \\ \cline{2-11}  & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & \(p\)**-Value** & \begin{tabular}{c} **RME vs.** \\ **SME** \\ **SME** \\ **Control** \\ \end{tabular} & \begin{tabular}{c} **RME vs.** \\ **Control** \\ \end{tabular} & \
\begin{tabular}{c} **RME vs.** \\ **Control** \\ \end{tabular} &
\begin{tabular}{c} **SME vs.** \\ **Control** \\ \end{tabular} \\ \hline \(\Delta\) SNP-SNA \(\wedge\) Go-Gn & 0.14 & 3.20 & 0.42 & 4.01 & 0.01 & 3.14 & 0.61 & 0.78 & 0.92 & 0.70 \\ \hline \(\Delta\) S-N \(\wedge\) SNP-SNA & \(-\)0.64 & 3.02 & 0.04 & 3.43 & 0.43 & 2.42 & 0.47 & 0.56 & 0.22 & 0.67 \\ \hline \(\Delta\) NSAr & 0.11 & 5.03 & 0.82 & 4.02 & 0.91 & 2.84 & 0.55 & 0.62 & 0.51 & 0.92 \\ \hline \(\Delta\) SrGo & 1.22 & 5.54 & 0.74 & 4.83 & \(-\)0.34 & 5.41 & 0.63 & 0.76 & 0.33 & 0.49 \\ \hline \(\Delta\) ArGoGn & \(-\)1.22 & 4.01 & 0.53 & 3.94 & \(-\)0.42 & 5.13 & 0.29 & 0.17 & 0.53 & 0.48 \\ \hline Jaraback’s sum & 0.13 & 3.42 & 2.01 & 4.11 & 0.24 & 3.41 & 0.71 & 0.10 & 0.90 & 0.11 \\ \hline \(\Delta\) U1 \(\wedge\) S-N & 3.11 & 9.82 & \(-\)3.33 & 5.04 & \(-\)0.21 & 4.93 & 0.46 & 0.02 & 0.29 & 0.04 \\ \hline \(\Delta\) U1 \(\wedge\) SNP-SNA & 2.64 & 10.34 & \(-\)2.61 & 4.93 & \(-\)0.43 & 3.61 & 0.13 & 0.11 & 0.42 & 0.11 \\ \hline \(\Delta\) L1 \(\wedge\) Go-Me & 3.69 & 5.72 & 2.94 & 4.31 & 0.62 & 3.73 & 0.61 & 0.16 & 0.92 & 0.06 \\ \hline \(\Delta\) U1 \(\wedge\) L1 & \(-\)1.60 & 8.91 & \(-\)1.41 & 5.32 & 0.91 & 4.61 & 0.53 & 0.92 & 0.22 & 0.11 \\ \hline \hline \end{tabular}  
* **Bold**: significant difference between groups.  
\end{table} 
Table 4: _Cont._permits an anterior positioning of the screw compared with appliances cemented on the first permanent molar, as already reported in previous research [32; 33]. Nevertheless, no significant difference was found between the three groups. The expansion in the anterior area can acquire more space for the upper incisors, which are then free to align spontaneously, even under the influence of the upper lip. [PERSON] and [PERSON] [34] reported that the pressure of the upper lip on the buccal side of the upper incisors showed a significant increase after maxillary expansion but started decreasing during the retention time. Conversely, the tongue pressure generated on the lingual side of the upper incisor demonstrated a significant decrease following palatal expansion but started increasing during the retention phase. This is in accordance with [PERSON] [35], who reported the theory of equilibrium, which demonstrates the natural alignment and retraction of the maxillary incisors. Similar studies reported no significant alterations for sagittal measurements [25; 27]. Both treated groups and the control group presented similar behavior for maxillary and mandibular changes after the treatment and the retention period, but with no statistically or clinically significant differences. Short- and long-term vertical skeletal variations related to RME were assessed specifically for the maxilla. [PERSON] et al. [25] reported minor changes with slight clinical significance. Furthermore, the long-term changes estimated for the mandibular plane angle were not reliable in the study of [PERSON] et al. [25]  
Unlike our study, not all previous research has considered an untreated control group. The present investigation showed no significant difference between the three groups for all the variables, but a statistically significant difference was found between T0 and T1 for the two groups of treated patients for the U1 \(\wedge\) S-N, U1 \(\wedge\) SNP-SNA and L1 \(\wedge\) Go-Me angles. This could be explained with the statistical consideration that the paired \(t\)-test is influenced by a small but steady difference between T0 and T1. In contrast, the one-way ANOVA test considers only the mean and standard deviation of the entire group.