## 4 Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Variables**} & **T2** & \(\Delta\)**T1–T2** & \multirow{2}{*}{_p-Value_} \\ \cline{2-3}  & & **Group 1 (_n_ = 19)** & \\ \hline \hline \multirow{4}{*}{PtV to Mx 7 (mm)} & **Group 2 (_n_ = 16)** & \multirow{4}{*}{0.001 **} \\  & 8.55 \(\pm\) 5.45 & & 2.01 \(\pm\) 1.46 & 0.001 ** \\ \cline{1-1} \cline{2-3} Palatal plane to Mx 7 (mm) & 16.12 \(\pm\) 2.91 & 0.21 \(\pm\) 1.02 & 0.426 \\ \cline{1-1} \cline{2-3} FH to functional occlusal plane (\({}^{\circ}\)) & 9.61 \(\pm\) 5.03 & \(-\)0.62 \(\pm\) 3.01 & 0.424 \\ \cline{1-1} \cline{2-3} FH to anatomical occlusal plane (\({}^{\circ}\)) & 8.66 \(\pm\) 4.91 & \(-\)1.96 \(\pm\) 2.88 & 0.016 * \\ \cline{1-1} \cline{2-3} FH to mandibular plane (\({}^{\circ}\)) & 7.73 \(\pm\) 8.45 & \(-\)0.06 \(\pm\) 1.20 & 0.854 \\ \cline{1-1} \cline{2-3} \cline{4-3}  & **Group 3 (_n_ = 16)** & & \\ \cline{1-1} \cline{2-3} \cline{4-3} \cline{4-3} PIV to Mx 7 (mm) & 7.92 \(\pm\) 2.61 & \multirow{2}{*}{1.12 \(\pm\) 1.43} & 0.007 ** \\ \cline{1-1} \cline{2-3} Palatal plane to Mx 7(mm) & 14.88 \(\pm\) 2.22 & \multirow{2}{*}{0.11 \(\pm\) 1.75} & 0.808 \\ \cline{1-1} \cline{2-3} FH to functional occlusal plane (\({}^{\circ}\)) & 9.20 \(\pm\) 4.77 & \(-\)1.46 \(\pm\) 3.89 & 0.155 \\ \cline{1-1} \cline{2-3} FH to anatomical occlusal plane (\({}^{\circ}\)) & 9.08 \(\pm\) 3.79 & \(-\)2.51 \(\pm\) 2.57 & 0.001 ** \\ \cline{1-1} \cline{2-3} FH to mandibular plane (\({}^{\circ}\)) & 26.16 \(\pm\) 4.79 & 0.15 \(\pm\) 1.01 & 0.561 \\ \hline \hline \end{tabular} Values are presented as mean \(\pm\) standard deviation. Paired _t_-tests were performed to compare before and after treatment. T1, pre-treatment; T2, post-treatment. *_p_ \(<\) 0.05, **_p_ \(<\) 0.01. See Figure 4 and Table 2 for definitions of each landmark.  
\end{table} 
Table 4: _Cont._The results of this study indicate that the cant of the anatomical occlusal plane can be increased according to the position of the TAD. Although the changes in the anatomical occlusal plane did not significantly differ among the three groups, the intragroup comparison revealed that the palatally positioned (groups 2 and 3) TADs groups showed an increase (steepening) in the anatomic occlusal plane angle after treatment, while bucally positioned TADs (group 1) produced no changes in the anatomical occlusal plane after treatment. This finding should be interpreted with caution. Despite the increase in the anatomical occlusal plane in groups 2 and 3, the other occlusal plane, i.e., the functional occlusal plane, did not show statistically significant changes. In this study, both the anatomical and functional occlusal planes were measured. Previous studies involving maxillary molar distalization measured the anatomic occlusal plane, and not many of them, if any, measured the functional occlusal plane. Class II malocclusions are often accompanied by a deep anterior overbite, and resolving the deep overbite can affect the anterior occlusal plane, which in turn affects the anatomical occlusal plane. This change is unrelated to maxillary molar distalization but can be misinterpreted as a result of maxillary molar distalization. During anterior bite opening, the intrusion of maxillary incisors may result in the flattening of the anatomical occlusal plane because the anterior overbite midpoint moves upward, whereas intrusion of the mandibular incisors may result in steepening of the anatomical occlusal plane. To avoid misinterpretation, a lateral cephalogram taken after leveling stage and just before distalization should be served as T1, as indicated by [PERSON] et al. and [PERSON] et al. [14,17]. Another way might be measuring the functional occlusal plane, as performed in this study. None of the three groups showed changes in the functional occlusal plane, whereas groups 2 and 3 showed significant increases in the anatomical occlusal plane. This inconsistency between the changes in the functional and anatomical occlusal planes leaves considerable room for thought.