# The Effects of Chewing Exercises on Masticatory Function after Surgical Orthodontic Treatment
## 2 Materials and Methods
### Methods of Measurement
#### 2.2.2 Three-Dimensional Computed Tomography (3D CT) Analysis  
Three-dimensional CT image reconstruction. The 3D CT scanning method was performed as reported by [PERSON] [18], and 3 DCT images were used at T1 and T2. The images were produced using an Aquilion 64 CT scanner (Toshiba Medical Systems Tokyo, Japan). The image parameters were tube current, 100 mA; tube voltage, 120 kV; slice thickness, 1 mm; field of view, 240 mm \(\times\) 240 mm. The patient was scanned from the chin to the glabella. A laser was used to stabilize the position of the patient's head. The vertical axis of the laser was the front view and the transverse \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Exercise Group (n = 10)**} & \multicolumn{4}{c}{**Control Group (n = 19)**} & \multicolumn{4}{c}{**Statistical Significance**} \\ \cline{2-13}  & \multicolumn{2}{c}{**T1**} & \multicolumn{2}{c}{**T2**} & \multicolumn{2}{c}{**CT1**} & \multicolumn{2}{c}{**CT2**} & \multicolumn{2}{c}{**_p_-Value**} & \\ \cline{2-13}  & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **T1-T2** & **CT1-CT2** & **T1-CT1** & **T2-CT2** \\ \hline \multicolumn{13}{l}{_Angle measurement_} \\ SNA (\({}^{\circ}\)) & 82.1 & 3.5 & 82.2 & 3.5 & 80.4 & 3.5 & 81.9 & 3.1 & NS & NS & NS & NS \\ SNB (\({}^{\circ}\)) & 83.5 & 4.3 & 81.1 & 4.3 & 80.7 & 4.1 & 78.6 & 3.0 & ** & NS & NS \\ ANB (\({}^{\circ}\)) & \(-\)1.5 & 3.1 & 1.1 & 2.4 & \(-\)0.2 & 3.8 & 3.2 & 3.0 & ** & NS & NS & NS \\ PMA (\({}^{\circ}\)) & 30.1 & 4.8 & 30.4 & 4.8 & 29.8 & 4.3 & 30.2 & 3.9 & NS & NS & NS & NS \\ FMIA (L1 to FH) (\({}^{\circ}\)) & 65.8 & 8.5 & 67.4 & 7.4 & 59.3 & 9.9 & 60 & 6.4 & NS & NS & NS & NS \\ IMPA (L1 to MP) (\({}^{\circ}\)) & 84.2 & 5.3 & 82.3 & 4.7 & 90.9 & 9.1 & 89.7 & 7.8 & NS & NS & NS & NS \\ Ul to SN (\({}^{\circ}\)) & 114.9 & 8.0 & 112.7 & 8.9 & 111.3 & 8.6 & 110.3 & 8.4 & NS & NS & NS & NS \\ \multicolumn{13}{l}{Interical angle (\({}^{\circ}\))} \\ \multicolumn{13}{l}{_Liner measurement_} \\ Overjet (mm) & \(-\)0.1 & 4.9 & 3.1 & 1.9 & \(-\)3.2 & 3.6 & 2.6 & 2.6 & ** & NS & NS & NS \\ Overbite (mm) & 0.4 & 1.5 & 2.0 & 1.7 & 0.8 & 1.0 & 2.4 & 1.3 & * & ** & NS & NS \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cephalometric measurements. Figure 2: Cephalometric measurements: 1. SNA (degrees), 2. SNB (degrees), 3. ANB (degrees), 4. FMIA (degrees), 5. Interincisal angle (degrees), 6. IMPA (degrees), 7. FMA (degrees), 8. U1—SN (degrees), 9. Overbite (mm), 10. Overjet (mm). axis of the laser was the plane between the tragia and the left side orbit. The occlusion was captured in a centric occlusion position with the lips lightly closed. The CT data were then taken and converted into Digital Imaging and Communications in Medicine (DICOM) format and then into Standard Triangulated Language (STL) format using DICOM software (OsiriX, Newton Graphics, Hokkaido Japan). The data were generated using 3D volume rendering software (Artec Studio 9, Artec 3D, Luxembourg City, Luxembourg). 3 DCT image reconstruction was performed after rendering of the cranial and mandibular bones. Defining the spatial coordinate system (3D CT images). The standard coordinates of the STL were set using 3D image analysis software (Body-Rugle, Medic Engineering, Kyoto, Japan). On the CT images, the coordinates were determined with reference to the superior border of the right and left external auditory canal poles (Po) and the right inferior orbital border (Or). The Frankfurt horizontal (FH) plane (axial plane) connected the Po and Or on both sides. The Coronal plane was drawn perpendicular to the axial direction through Po on both sides. The sagittal plane was defined as the plane passing through the center of Po from left to right and perpendicular to the axial direction. The X axis was the line defined through the left and right Po. The Y axis was a straight line through the center of the left and right Po and perpendicular to the FH plane. The Z axis (Figure 3) was the line through the origin and perpendicular to the X axis.