## 3 Results  
The results showed a significantly lower marginal and internal fit in the in-lab (open type) group at all measurement positions (\(p\) < 0.001; Figure 6; Table 1). The mean value of marginal fit was significantly different in the in-lab (open type) group (113.3 \(\pm\) 62.3 \(\upmu\)m) and the chairside (closed type) group (210.8 \(\pm\) 83 \(\upmu\)m) (\(p\) < 0.001).  
The trueness of the milling unit was significantly different in the in-lab (open type) group (46.7 \(\pm\) 11.7 \(\upmu\)m) and the chairside (closed type) group (27.7 \(\pm\) 6.1 \(\upmu\)m) (\(p\) < 0.001; Figure 7; Table 2). Comparing the color difference map of the occlusal region in Figure 8, the in-lab (open type) group shows blue zone (excessive milling) more than red. On the other hand, the chairside (closed type) group shows red zone (insufficient milling) more than blue.  
Figure 5: Measurements of the marginal and internal fit. (**A**) Fit check using impression materials. (**B**) Inner surface scan of the 3-unit fixed dental prosthesis (FDP) with impression materials. (**C**) Inner surface scan of the 3-unit FDP without impression materials. (**D**) Superimposition. (**E**) Measurements of the marginal and internal fit in a hypothetical plane.  
Figure 6: Comparison of the marginal and internal fit mean values by digital workflows. ***, Significant (\(p<0.001\)).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**System**} & \multicolumn{2}{c}{**Margin**} & \multicolumn{2}{c}{**Chamfer**} & \multicolumn{2}{c}{**Axial**} & \multicolumn{2}{c}{**Angle**} & \multicolumn{2}{c}{**Occlusal**} \\ \cline{2-5}  & \multicolumn{5}{c}{**Fitness (\(\mu\)m), Mean \(\pm\) SD**} \\ \hline
**Chairside group** & **210.8 \(\pm\) 83** & **143.4 \(\pm\) 82.1** & **216.2 \(\pm\) 79.2** & 356.9 \(\pm\) 79.6 & 382.5 \(\pm\) 91.4 \\ \hline In-lab group & 113.3 \(\pm\) 62.3 & 74.6 \(\pm\) 58.5 & 155.3 \(\pm\) 61.9 & 80 \(\pm\) 47.8 & 232.1 \(\pm\) 183 \\ \hline \(P\) & \textless{}0.001 *** & \textless{}0.001 *** & \textless{}0.001 *** & \textless{}0.001 *** & \textless{}0.001 *** \\ \hline RMS: Root mean square. Significance was determined by the *** Mann–Whitney U-test: \(p<0.001\).  
\end{table}
Table 1: Comparison of the marginal and internal fit according to digital workflows.  
Figure 7: Comparison of the trueness mean values by digital workflows. ***, Significant (\(p<0.001\)).  
The results of the correlation between the trueness of the milling unit and the fitness are shown in Figure 9. The trueness and internal fit showed a positive correlation (correlation coefficient = 0.621) only in the in-lab (open type) group (\(p\) = 0.013). There was no significant correlation between the trueness and marginal fit in the in-lab (open type) group (\(p\) = 0.070). There was no significant correlation  
\begin{table}
\begin{tabular}{c c} \hline \hline
**System** & **Trueness (\(\upmu\)), Mean \(\pm\) SD** \\ \hline Chairside group & 27.7 \(\pm\) 6.1 \\ \hline In-lab group & 46.7 \(\pm\) 11.7 \\ \hline \(\mathbf{P}\) & \textless{}0.001 *** \\ \hline \hline \end{tabular}  
Significance was determined by the *** Mann–Whitney U-test: \(p\) \textless{} 0.001  
\end{table}
Table 2: Comparison of the trueness values according to digital workflows.  
Figure 8: Comparison of the color difference map of trueness by digital workflows.  
between trueness and marginal fit (\(p=0.855\)), as well as the trueness and internal fit (\(p=0.701\)), in the chairside (closed type) group.