## 3 Results  
There were significant differences in the accuracy of scanning all teeth among the scanners (\(P\) < 0.001) (Table 1). Except for the two types of laboratory scanners (3 Shape E1 and DOF), all intraoral scanners showed improved accuracy from the posterior (first premolar to second molar) to the anterior (first incisor to the canine tooth) (Table 1, Figure 3). Figure 3: Comparison of the RMS value per tooth (#27–#17) according to the scanner. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Tool Type**} & **3 Shape E1** & **DOF** & **CS3300** & **CS3600** & **Tinos2** & **Tinos3** & **i500** & **P** \\ \hline \multicolumn{1}{c}{**RMS (sum). Mean \(\pm\) SD**} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \\ \hline
**\#27** & \(13.7\pm 1.2\,^{a}\) & \(37.6\pm 1.5\,^{ab}\) & \(126.8\pm 51.6\,^{c}\) & \(76.6\pm 43.6\,^{ab}\) & \(192.9\pm 134.1\,^{d}\) & \(68.8\pm 40.9\,^{abc}\) & \(80.4\pm 55.2\,^{bc}\) & \(<\)0.001 \\
**\#26** & \(19.5\pm 0.9\,^{a}\) & \(19.6\pm 1.1\,^{a}\) & \(61.5\pm 22\,^{a}\) & \(59.1\pm 35\,^{a}\) & \(148.5\pm 102.9\,^{b}\) & \(41\pm 27.7\,^{a}\) & \(64\pm 39.2\,^{a}\) & \(<\)0.001 \\
**\#25** & \(27.5\pm 2.7\,^{a}\) & \(15.4\pm 0.7\,^{a}\) & \(40.6\pm 11.6\,^{a}\) & \(40.4\pm 21.2\,^{a}\) & \(115.5\pm 71.6\,^{b}\) & \(33.5\pm 14.3\,^{a}\) & \(47.5\pm 22.9\,^{a}\) & \(<\)0.001 \\
**\#24** & \(22.3\pm 1.6\,^{ab}\) & \(148.8\pm 0.8\,^{a}\) & \(40.6\pm 12.4\,^{b}\) & \(33.3\pm 15.7\,^{ab}\) & \(92.7\pm 54\,^{c}\) & \(26.6\pm 7.8\,^{ab}\) & \(38.7\pm 15.8\,^{ab}\) & \(<\)0.001 \\
**\#23** & \(21.3\pm 0.9\,^{a}\) & \(15.2\pm 0.7\,^{a}\) & \(42.6\pm 10.4\,^{b}\) & \(30.2\pm 9.9\,^{b}\) & \(71.6\pm 37.1\,^{c}\) & \(23.1\pm 4.2\,^{a}\) & \(29.7\pm 9.1\,^{ab}\) & \(<\)0.001 \\
**\#22** & \(13.9\pm 1.1\,^{a}\) & \(18.6\pm 0.4\,^{a}\) & \(40.6\pm 16.5\,^{bc}\) & \(26.3\pm 5.4\,^{ab}\) & \(52.5\pm 18.5\,^{c}\) & \(24.2\pm 6.2\,^{a}\) & \(29.6\pm 9.5\,^{ab}\) & \(<\)0.001 \\
**\#21** & \(9.5\pm 0.2\,^{a}\) & \(18.7\pm 0.3\,^{ab}\) & \(38.6\pm 15.3\,^{c}\) & \(27.3\pm 5\,^{bc}\) & \(44.1\pm 16.6\,^{a}\) & \(32.2\pm 9.3\,^{c}\) & \(40.3\pm 12.8\,^{c}\) & \(<\)0.001 \\
**\#11** & \(9.9\pm 0.2\,^{a}\) & \(18.7\pm 0.5\,^{ab}\) & \(40.4\pm 14.4\,^{c}\) & \(24.6\pm 4\,^{abc}\) & \(35.5\pm 7.8\,^{ab}\) & \(32.8\pm 11.6\,^{abc}\) & \(40.4\pm 16.2\,^{c}\) & \(<\)0.001 \\
**\#12** & \(9.5\pm 0.3\,^{a}\) & \(19.9\pm 0.4\,^{ab}\) & \(44.7\pm 16.1\,^{c}\) & \(23.9\pm 6.7\,^{ab}\) & \(30.1\pm 4.8\,^{bc}\) & \(28.3\pm 10.6\,^{bc}\) & \(46.4\pm 31.6\,^{c}\) & \(<\)0.001 \\
**\#13** & \(18.8\pm 1.5\,^{a}\) & \(20.5\pm 0.4\,^{ab}\) & \(43.1\pm 17.2\,^{b}\) & \(27\pm 7.2\,^{abc}\) & \(46.3\pm 11.1\,^{c}\) & \(23.6\pm 6.9\,^{a}\) & \(73\pm 46.2\,^{a}\) & \(<\)0.001 \\
**\#14** & \(19.5\pm 2\,^{a}\) & \(18.3\pm 0.6\,^{a}\) & \(36.8\pm 15.7\,^{ab}\) & \(31.2\pm 10.1\,^{ab}\) & \(56.4\pm 15.4\,^{b}\) & \(30.6\pm 15.4\,^{ab}\) & \(108.2\pm 69.5\,^{c}\) & \(<\)0.001 \\
**\#15** & \(27.6\pm 1.6\,^{b}\) & \(21.8\pm 0.5\,^{a}\) & \(43.3\pm 19.1\,^{ab}\) & \(40.3\pm 15.8\,^{ab}\) & \(64.4\pm 23.5\,^{b}\) & \(34.3\pm 22.2\,^{b}\) & \(145.3\pm 09.9\,^{a}\) & \(<\)0.001 \\
**\#16** & \(21.3\pm 1.1\,^{a}\) & \(25.2\pm 0.6\,^{a}\) & \(55.5\pm 34.2\,^{a}\) & \(51.5\pm 28.2\,^{a}\) & \(65.8\pm 39.2\,^{a}\) & \(54.6\pm 37.6\,^{a}\) & \(223\pm 139.8\,^{b}\) & \(<\)0.001 \\
**\#17** & \(15.5\pm 2\,^{a}\) & \(40.3\pm 0.9\,^{ab}\) & \(83.2\pm 61.4\,^{a}\) & \(69.1\pm 38\,^{ab}\) & \(115.2\pm 52.6\,^{b}\) & \(76.6\pm 53.3\,^{ab}\) & \(339.6\pm 19.5\,^{ab}\) & \(<\)0.001 \\
**\#21** & \(60.001\) & \(<\)0.001 & \(<\)0.001 & \(<\)0.001 & \(<\)0.001 & \(<\)0.001 & \(<\)0.001 & \(<\)0.001 \\ \hline \hline \end{tabular}  
* 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 (\(P<0.0017\)).  
\end{table}