## 3 Results
### Ergonomics and Safety  
We tested the ease with which the posterior mandibular ramal area could be approached by the robot arm osteotomy through an intraoral approach in the dummy operating theater. The surgeons' natural position could be guaranteed and enough space was provided (Figure 7). The vertical cut with the long fissure bur and the inferior cut were successfully simulated in the direct direction toward the operating site. For the superior cut, the robot arm should be rotated to horizontal. We set the midpoint of robot position so that, when the robot turned, it did not hit the patient or the surgeon. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & **Robot Surgery** & **Hand Surgery** & \(p\)**Value** \\ \hline \multirow{2}{*}{Position} & RMS & 0.70 \(\pm\) 0.34 & 1.83 \(\pm\) 0.65 & \textless{}0.001 \\  & variance & 0.11 & 0.43 & \textless{}0.001 \\ \hline \multirow{2}{*}{Length} & Mean \(\pm\) SD & 0.35 \(\pm\) 0.19 & 0.62 \(\pm\) 0.37 & 0.009 \\  & variance & 0.03 & 0.14 & 0.004 \\ \hline \multirow{2}{*}{Angle} & Mean \(\pm\) SD & 1.32 \(\pm\) 0.96 & 5.96 \(\pm\) 3.47 & \textless{}0.001 \\  & variance & 0.93 & 12.08 & \textless{}0.001 \\ \hline \multirow{2}{*}{Depth} & Mean \(\pm\) SD & 0.59 \(\pm\) 0.46 & 0.40 \(\pm\) 0.31 & 0.030 \\  & variance & 0.21 & 0.10 & 0.014 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of accuracy between robotic and manual surgeries for position, length, angle and depth errors. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & \multicolumn{3}{c}{**Errors of Robot Surgery**} & \multicolumn{3}{c}{**Errors of Hand Surgery**} \\
**Cut** & **Category** & & **6 mm Disc** & **20 mm Disc** & \(p\)**Value** & **6 mm Disc** & **20 mm Disc** & \(p\)**Value** \\ \hline \multirow{4}{*}{Post. cut} & Position (mm) & RMS & 0.65 \(\pm\) 0.17 & 0.59 \(\pm\) 0.22 & 0.602 & 1.93 \(\pm\) 0.37 & 1.60 \(\pm\) 0.51 & 0.347 \\  & & variance & 0.03 & 0.05 & 0.13 & 0.26 & \\  & Angle (\({}^{\circ}\)) & Mean \(\pm\) SD & 0.72 \(\pm\) 0.50 & 1.81 \(\pm\) 1.29 & 0.754 & 6.13 \(\pm\) 3.75 & 8.10 \(\pm\) 2.67 & 0.057 \\  & & Variance & 0.25 & 1.67 & & 14.07 & 7.11 \\  & Length (mm) & Mean \(\pm\) SD & 0.40 \(\pm\) 0.14 & 0.33 \(\pm\) 0.20 & 0.599 & 0.71 \(\pm\) 0.26 & 0.91 \(\pm\) 0.44 & 0.602 \\  & Variance & 0.02 & 0.04 & & 0.07 & 0.19 & \\ \hline Ant. cut & Position (mm) & RMS & 1.00 \(\pm\) 0.24 & 1.28 \(\pm\) 0.22 & 0.251 & 2.03 \(\pm\) 0.54 & 2.53 \(\pm\) 0.42 & 0.347 \\  & Variance & 0.06 & 0.05 & & 0.29 & 0.17 & \\  & Angle (\({}^{\circ}\)) & Mean \(\pm\) SD & 0.93 \(\pm\) 0.62 & 1.17 \(\pm\) 0.69 & 0.117 & 7.15 \(\pm\) 3.15 & 1.74 \(\pm\) 1.46 & 0.602 \\  & & Variance & 0.38 & 0.47 & & 9.90 & 2.14 \\  & Length (mm) & Mean \(\pm\) SD & 0.40 \(\pm\) 0.24 & 0.29 \(\pm\) 0.13 & 0.347 & 0.39 \(\pm\) 0.27 & 0.48 \(\pm\) 0.24 & 0.463 \\  & Variance & 0.06 & 0.02 & & 0.07 & 0.06 & \\ \hline Inf. cut & Position (mm) & RMS & 0.36 \(\pm\) 0.32 & 0.52 \(\pm\) 0.18 & 0.602 & 2.29 \(\pm\) 0.51 & 2.65 \(\pm\) 0.62 & 0.754 \\  & Variance & 0.10 & 0.03 & & 0.26 & 0.38 & \\  & Angle (\({}^{\circ}\)) & Mean \(\pm\) SD & 0.29 \(\pm\) 0.65 & 1.58 \(\pm\) 0.96 & 0.753 & 7.58 \(\pm\) 2.99 & 7.23 \(\pm\) 3.55 & 0.754 \\  & Variance & 0.42 & 0.92 & & 8.94 & 12.63 & \\  & Depth (mm) & Mean \(\pm\) SD & 0.36 \(\pm\) 0.35 & 0.45 \(\pm\) 0.30 & 0.530 & 0.32 \(\pm\) 0.24 & 0.51 \(\pm\) 0.33 & 0.251 \\  & Variance & 0.12 & 0.09 & & 0.06 & 0.11 & \\ \hline Sup. cut & Position (mm) & RMS & 0.86 \(\pm\) 0.45 & 0.53 \(\pm\) 0.31 & 0.602 & 0.79 \(\pm\) 0.20 & 1.09 \(\pm\) 0.41 & 0.465 \\  & Variance & 0.20 & 0.09 & & 0.04 & 0.16 & \\  & Angle (\({}^{\circ}\)) & Mean \(\pm\) SD & 1.45 \(\pm\) 1.08 & 1.30 \(\pm\) 1.10 & 0.917 & 4.09 \(\pm\) 2.80 & 5.29 \(\pm\) 2.52 & 0.602 \\  & Variance & 1.17 & 1.20 & & 7.83 & 6.35 & \\  & Depth (mm) & Mean \(\pm\) SD & 0.44 \(\pm\) 0.21 & 1.13 \(\pm\) 0.44 & 0.009 & 0.30 \(\pm\) 0.25 & 0.46 \(\pm\) 0.36 & 0.173 \\  & Variance & 0.05 & 0.19 & & 0.06 & 0.13 & \\ \hline \hline \end{tabular}
\end{table}