## 3 Results  
### Statistical Analysis  
Data were checked for normality. Continuous variables are given as means \(\pm\) standard deviations (SD) and medians with interquartile range, and categorical variables are shown as the number or percentage of subjects. The baseline differences among the groups were tested with one-way analysis of variance with group as a factor, or with the Kruskal-Wallis test. Intragroup differences over time were tested with a paired \(t\)-test or [PERSON]'s signed-rank test. One-way analysis of variance, or the Kruskal-Wallis test, was performed again to investigate the association of differences over time with the groups. Post hoc comparisons were carried out with the Bonferroni method. Differences with a \(p\)-value \(<\) 0.05 were selected as significant. Data were acquired and analyzed in the R v3.4.4 software [31]. Data from 68 patients were analyzed. The mean age was 13.4 years. The minimum age was 7 years, and the maximum age was 27 years. The mean therapy duration was 16.5 months. The demographic and clinical characteristics of the groups are shown in Table 1. No miniscrew failures were observed. The mean amount of activation of the expansion screw was 7.63 \(\pm\) 1.74 mm (range, 3-13.8 mm), and the duration of the expansion ranged from 7 to 23 days. The baseline parameter differences between groups are shown in Tables 2 and 3. No significant differences were found at baseline, except for III cent and VI L (\(p\) = 0.015 and 0.031, respectively), and for the torque of 1.6 (\(p\) = 0.047). \begin{table}
\begin{tabular}{c c c c} \hline  & **Group 1 (CS1–CS2)** & **Group 2 (CS3–CS4)** & **Group 3 (CS5–CS6)** \\ \hline
**N** & 21 & 28 & 19 \\
**Sex** & & & \\
**M** & 12 & 10 & 7 \\
**F** & 9 & 18 & 12 \\
**Age (years)** & 10.21 \(\pm\) 1.34 & 13.37 \(\pm\) 1.36 & 17.14 \(\pm\) 3.48 \\
**Mean nominal expansion (mm)** & 7.13 \(\pm\) 1.27 & 7.73 \(\pm\) 1.84 & 8.04 \(\pm\) 1.98 \\
**Mean activation time (days)** & 12.86 \(\pm\) 2.29 & 13.93 \(\pm\) 2.84 & 14.21 \(\pm\) 2.53 \\
**Mean treatment duration (months)** & 21.96 \(\pm\) 11.47 & 14.16 \(\pm\) 5.12 & 14.11 \(\pm\) 6.29 \\
**Mean time difference of superimposed** & 28.98 \(\pm\) 13.75 & 19.78 \(\pm\) 8.48 & 17.31 \(\pm\) 28.09 \\
**models (months)** & & & \\ \hline \end{tabular}
\end{table} 
Table 1: Demographic and clinical characteristics of groups. M: male; F: female. \begin{table}
\begin{tabular}{c c c c} \hline  & **Group 1 (CS1–CS2)** & **Group 2 (CS3–CS4)** & **Group 3 (CS5–CS6)** & **Intergroup** \\ \cline{2-3}  & & & \(p\)**-Value** \\ \hline
**N** & 21 & 28 & 19 \\ \hline
**III (mm)** & & & \\ \hline C & 31.34 \(\pm\) 2.27 & 33.18 \(\pm\) 2.78 & 32.20 \(\pm\) 2.47 & 0.1  
In terms of transversal expansion, significant intragroup differences over time were found for all parameters in all groups (Table 4). \begin{table}
\begin{tabular}{c c c c c} \hline  & **Group 1 (CS1–CS2)** & **Group 2 (CS3–CS4)** & **Group 3 (CS5–CS6)** &
\begin{tabular}{c} **Intergroup** \\ _p_-Value** \\ \end{tabular} \\ \hline L & \(25.32\pm 2.32\) & \(25.82\pm 2.37\) & \(24.76\pm 2.04\) & \(0.298\) \\ \hline
**V (mm)** & & & & \\ \hline C & \(44.77\pm 2.09\) & \(43.42\pm 3.41\) & \(42.86\pm 3.08\) & \(0.607\) \\ \hline cent & \(39.18\pm 1.97\) & \(38.42\pm 3.09\) & \(37.73\pm 2.77\) & \(0.624\) \\ \hline L & \(30.14\pm 1.90\) & \(29.93\pm 2.64\) & \(29.45\pm 2.32\) & \(0.798\) \\ \hline
**VI (mm)** & & & & \\ \hline C & \(46.99\)[45.40, 50.28] & \(48.26\)[47.47, 49.45] & \(48.74\)[47.21, 50.87] & \(0.130\) \\ \hline cent & \(42.61\pm 3.07\) & \(44.15\pm 2.07\) & \(44.21\pm 2.34\) & \(0.063\) \\ \hline \end{tabular} \
\begin{tabular}{c c c} \hline  & & \(0.031\) \\ \hline L & \(30.57\pm 2.29\) & \(31.97\pm 1.90\) & \(32.16\pm 2.15\) &
\begin{tabular}{c} \(0.031\) \\ \hline Group 1 vs. Group 2: 0.071 \\ \hline Group 1 vs. Group 3: 0.058 \\ \hline Group 2 vs. Group 3: 1.000 \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._