## 3 Results  
The patients' descriptive statistics, such as age and lateral cephalometric analyses in males and females, are presented in Table 1. The mean age of the patients was 25.8 \(\pm\) 8.9 years (males, 24.6 \(\pm\) 6.1 years; females, 27.0 \(\pm\) 11.1 years). There were no significant differences in the age and cephalometric variables between male and female patients. Of the 53 patients, successful maxillary skeletal expansion was performed in 41 (77.4%) patients. As a result of MARPE, SNA (_p_ < 0.001), ANB (_p_ = 0.001), A-Nper (_p_ < 0.001), SN-MP (_p_ = 0.001), and Rickett's LFH (_p_ = 0.002) showed significant increases. Overbite showed a significant decrease following MARPE (_p_ = 0.009, Table 2). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & \multirow{2}{*}{**Total**} & \multicolumn{4}{c}{**Sex Differences**} \\ \cline{3-5}  & & **Male (_u = 27_)** & **Female (_u = 26_)** & \\ \cline{2-5}  & **MEAN \(\pm\) SD** & **MEAN \(\pm\) SD** & **MEAN \(\pm\) SD** & _p_**-Value** \\ \hline Age (year) & 25.7 \(\pm\) 8.7 & 24.6 \(\pm\) 6.1 & 27 \(\pm\) 11.1 & 0.343 \\ SNA (\({}^{\circ}\)) & 80.5 \(\pm\) 4.0 & 80.3 \(\pm\) 4.0 & 80.5 \(\pm\) 4.2 & 0.798 \\ SNB (\({}^{\circ}\)) & 79.8 \(\pm\) 4.1 & 79.6 \(\pm\) 4.8 & 79.8 \(\pm\) 3.6 & 0.893 \\ ANB (\({}^{\circ}\)) & 0.7 \(\pm\) 3.3 & 0.6 \(\pm\) 3.8 & 0.8 \(\pm\) 3.0 & 0.870 \\ A-N perp (mm) & \(-\)0.2 \(\pm\) 3.6 & \(-\)0.5 \(\pm\) 4.0 & \(-\)0.2 \(\pm\) 3.2 & 0.815 \\ SN-MP (\({}^{\circ}\)) & 34 \(\pm\) 5.6 & 32.8 \(\pm\) 5.9 & 35.4 \(\pm\) 5 & 0.095 \\ Overbite (mm) & 0.6 \(\pm\) 2 & 1.1 \(\pm\) 2 & 0.2 \(\pm\) 1.9 & 0.092 \\ Overjet (mm) & 2.1 \(\pm\) 2.5 & 1.9 \(\pm\) 2.7 & 2.4 \(\pm\) 2.3 & 0.458 \\ Rickett’s LFH (mm) & 48.2 \(\pm\) 4.4 & 48.5 \(\pm\) 4.7 & 48.1 \(\pm\) 4.3 & 0.778 \\ \hline \hline \end{tabular} SNA: Sella–nasion point A, SNB: Sella–nasion point B. ANB: Point A–nsion point B. A–N perp: Distance from point A to nasion perpendicular. SN-MP: Mandibular–plane angle defined as the angle between the sella–nasion plane and the mandibular plane. [PERSON]’s LFH: [PERSON]’s lower facial height.  
\end{table} 
Table 1: Patient characteristics. Figure 3: Monocortical versus bicortical fixation of the microimplant-assisted rapid palatal expander. (**A**) Monocortical fixation refers to the microimplants engaged only in the palatal cortical bone, and (**B**) bicortical fixation indicates microimplants engaged in the palatal and nasal layers of the cortical bone. The proportion of females was higher in the S group than in the F group, while that of males was higher in the F group. This difference in the distribution of males and females in the two groups was significant (\(p\) = 0.002, Table 3), but there were no significant associations with the type of appliance and the mode of microimplant fixation (monocortical vs. bicortical) between the S and F groups (Table 3). Based on a logistic regression model, significant factors associated with the success of MARPE and the odds ratios for each factor are displayed in Table 4. Age, sex, and A-N perp showed a significant association with the success of MARPE (Table 4). Other cephalometric variables and suture densities were not significant as predictors for MARPE success; [PERSON]'s lower facial height showed borderline nonsignificance. A yearly increase by age was likely to show MARPE failure with an odds ratio of 0.869 (\(p\) = 0.019). MARPE showed more tendency to fail in males than in females, with an odds ratio of 0.022 (\(p\) = 0.002). A greater A-N perp at T1 indicated a greater chance of success, with an odds ratio of 1.591 (\(p\) = 0.015).