## 3 Results

Table 1: Comparison of the root mean square (RMS) values per tooth using five intraoral scanners and two dental laboratory scanners. In all the scanners, there was a significant difference in the accuracy between the anterior and posterior regions (\(P<0.001\)) (Table 2). The accuracy was much better in the anterior region than in the posterior region (Table 2, Figure 4). As for the accuracy of the overall region and on the virtual plane, the laboratory scanners (3 Shape E1 and DOF) showed an accuracy of lower than 30 \(\upmu\)m, and laboratory scanners had no significant difference (\(P>0.05\)); however, there was a big deviation ranging from 44.2-164.1 \(\upmu\)m in the intraoral scanners by type, and intraoral scanners had a significant difference (\(P<0.001\)) (Table 3, Figure 5). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **3 Shape E1** & **DOF** & **CS3500** & **CS3600** & **Trios2** & **Trios3** & **i500** & \(P\) \\ \hline \multicolumn{10}{c}{**RMS (\(\upmu\)m), Mean \(\pm\) SD**} \\ \hline
**Overall** & 14.3 \(\pm\) 0.3\({}^{\,\mathrm{a}}\) & 24.3 \(\pm\) 0.4\({}^{\,\mathrm{ab}}\) & 62.4 \(\pm\) 19.8\({}^{\,\mathrm{cd}}\) & 49.3 \(\pm\) 21.1 \({}^{\,\mathrm{bc}}\) & 92.8 \(\pm\) 32.7\({}^{\,\mathrm{d}}\) & 44.2 \(\pm\) 15.7\({}^{\,\mathrm{ac}}\) & 143 \(\pm\) 69.64\({}^{\,\mathrm{e}}\) & \(<\)0.001 \\
**Plane** & 23.6 \(\pm\) 0.6\({}^{\,\mathrm{a}}\) & 28.7 \(\pm\) 0.4\({}^{\,\mathrm{a}}\) & 56.5 \(\pm\) 25.5\({}^{\,\mathrm{a}}\) & 59.9 \(\pm\) 26.8\({}^{\,\mathrm{a}}\) & 112.3 \(\pm\) 50.9\({}^{\,\mathrm{b}}\) & 47.6 \(\pm\) 23\({}^{\,\mathrm{a}}\) & 164.1 \(\pm\) 84.7\({}^{\,\mathrm{c}}\) & \(<\)0.001 \\ \hline \multicolumn{10}{c}{RMS: root mean square. Significant by Kruskal–Wallis test; \(P<0.05\). Different letters indicate the significant differences among the scanner groups by Mann–Whitney U-test and Bonferroni correction method (\(P<0.0017\)).} \\ \hline \end{tabular}
\end{table} 
Table 2: Comparison of the RMS values of the anterior and posterior regions using five intraoral scanners and two dental laboratory scanners. Figure 4: Comparison of the RMS value per anterior and posterior region according to the scanner. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **3 Shape E1** & **DOF** & **CS3500** & **CS3600** & **Trios2** & **Trios3** & **i500** & \(P\) \\ \hline \multicolumn{10}{c}{**RMS (\(\upmu\)m), Mean \(\pm\) SD**} \\ \hline
**Overall** & 14.3 \(\pm\) 0.3\({}^{\,\mathrm{a}}\) & 24.3 \(\pm\) 0.4\({}^{\,\mathrm{ab}}\) & 62.4 \(\pm\) 19.8\({}^{\,\mathrm{cd}}\) & 49.3 \(\pm\) 21.1 \({}^{\,\mathrm{bc}}\) & 92.8 \(\pm\) 32.7\({}^{\,\mathrm{d}}\) & 44.2 \(\pm\) 15.7\({}^{\,\mathrm{ac}}\) & 143 \(\pm\) 69.64\({}^{\,\mathrm{e}}\) & \(<\)0.001 \\
**Plane** & 23.6 \(\pm\) 0.6\({}^{\,\mathrm{a}}\) & 28.7 \(\pm\) 0.4\({}^{\,\mathrm{a}}\) & 56.5 \(\pm\) 25.5\({}^{\,\mathrm{a}}\) & 59.9 \(\pm\) 26.8\({}^{\,\mathrm{a}}\) & 112.3 \(\pm\) 50.9\({}^{\,\mathrm{b}}\) & 47.6 \(\pm\) 23\({}^{\,\mathrm{a}}\) & 164.1 \(\pm\) 84.7\({}^{\,\mathrm{c}}\) & \(<\)0.001 \\ \hline \multicolumn{10}{c}{RMS: root mean square. Significant by Kruskal–Wallis test; \(P<0.05\). Different letters indicate the significant differences among the scanner groups by Mann–Whitney U-test and Bonferroni correction method (\(P<0.0017\)).} \\ \hline \end{tabular}
\end{table} 
Table 3: Comparison of the overall and virtual plane RMS values using five intraoral scanners and two dental laboratory scanners. On the color difference map, the range of green zone appeared the most in the laboratory scanners (Figure 6A,B), while the range of green zone was smaller in the intraoral scanners (Figure 6C-H). Figure 5: Comparison of the RMS value of the overall region according to the scanner. Different letters indicate the significant differences among the scanner groups by Mann–Whitney U-test and Bonferroni correction method (\(P<0.0017\)).