## 3 Results  
Descriptive statistics (mean and SD) were used to describe the quantitative color difference (\(\Delta\)E). The Bonferroni post hoc test was used for multiple comparisons between the various factors (Type resin/Staining Solution/Immersion Time). Also, interactive plots for mean color differences between the type of resin, staining solutions, and time periods with the same confidence interval (95%) were produced. The Mean \(\Delta\)E values with their confidence intervals of all denture base resin materials in the five solutions used for all immersion periods are listed in Table 3.  
Figure 2: The typical basic parts for optical measurements. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Time Label**} & **Solution Type** & \multirow{2}{*}{**Material**} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{**Std. Error**} & \multirow{2}{*}{**Lower Bound**} & \multirow{2}{*}{**Upper Bound**} \\ \hline \multirow{8}{*}{**Water**} & & H & 0.103 & 0.136 & \(-\)0.168 & 0.374 \\ \cline{3-7}  & & T & 0.084 & 0.108 & \(-\)0.131 & 0.299 \\  & & S & 0.116 & 0.118 & \(-\)0.119 & 0.351 \\ \cline{3-7}  & & H & 0.667 & 0.136 & 0.396 & 0.937 \\ \cline{3-7}  & & T & 0.955 & 0.108 & 0.740 & 1.170 \\  & & S & 1.101 & 0.118 & 0.866 & 1.336 \\ \hline \multirow{2}{*}{**24 h**} & & H & 2.164 & 0.136 & 1.894 & 2.435 \\  & & T & 2.096 & 0.108 & 1.881 & 2.311 \\ \cline{3-7}  & & S & 1.953 & 0.118 & 1.717 & 2.188 \\ \hline \multirow{2}{*}{**Coffee**} & & H & 0.241 & 0.136 & \(-\)0.030 & 0.512 \\  & & T & 0.179 & 0.108 & \(-\)0.037 & 0.394 \\  & & S & 0.209 & 0.118 & \(-\)0.026 & 0.445 \\ \hline \multirow{2}{*}{**Coke\({}^{\text{\textregistered}}\)**} & & H & 0.144 & 0.136 & \(-\)0.127 & 0.415 \\  & & T & 0.228 & 0.108 & 0.012 & 0.443 \\  & & S & 0.097 & 0.118 & \(-\)0.138 & 0.332 \\ \hline \multirow{2}{*}{**Water**} & & H & 0.184 & 0.115 & \(-\)0.045 & 0.413 \\  & & T & 0.252 & 0.091 & 0.070 & 0.434 \\ \cline{3-7}  & & S & 0.093 & 0.100 & \(-\)0.106 & 0.292 \\ \hline \multirow{2}{*}{**Red\_Wine**} & & H & 1.270 & 0.115 & 1.041 & 1.499 \\ \cline{2-7}  & & T & 1.895 & 0.091 & 1.713 & 2.077 \\  & & S & 2.348 & 0.100 & 2.149 & 2.547 \\ \hline \multirow{2}{*}{**6 days**} & & H & 2.855 & 0.115 & 2.626 & 3.083 \\  & & T & 3.119 & 0.091 & 2.937 & 3.301 \\  & & S & 2.744 & 0.100 & 2.546 & 2.943 \\ \hline \multirow{2}{*}{**Coffee**} & & H & 0.429 & 0.115 & 0.201 & 0.658 \\  & & T & 0.393 & 0.091 & 0.211 & 0.575 \\ \cline{3-7}  & & S & 0.539 & 0.100 & 0.340 & 0.737 \\ \hline \multirow{2}{*}{**Coke\({}^{\text{\textregistered}}\)**} & & H & 0.452 & 0.115 & 0.223 & 0.681 \\  & & T & 0.519 & 0.091 & 0.337 & 0.701 \\  & & S & 0.478 & 0.100 & 0.280 & 0.677 \\ \hline \multirow{2}{*}{**Water**} & & H & 0.602 & 0.124 & 0.355 & 0.849 \\ \cline{3-7}  & & T & 1.075 & 0.099 & 0.879 & 1.272 \\  & & S & 0.992 & 0.108 & 0.778 & 1.207 \\ \hline \multirow{2}{*}{**Red\_Wine**} & & H & 1.966 & 0.124 & 1.718 & 2.213 \\  & & T & 2.746 & 0.099 & 2.550 & 2.943 \\  & & S & 2.992 & 0.108 & 2.777 & 3.207 \\ \hline \multirow{2}{*}{**30 days**} & & H & 4.021 & 0.124 & 3.774 & 4.268 \\  & & T & 3.882 & 0.099 & 3.686 & 4.079 \\ \cline{3-7}  & & S & 4.175 & 0.108 & 3.960 & 4.390 \\ \hline \multirow{2}{*}{**Coffee**} & & H & 1.065 & 0.124 & 0.818 & 1.312 \\  & & T & 0.833 & 0.099 & 0.637 & 1.030 \\  & & S & 1.011 & 0.108 & 0.796 & 1.226 \\ \hline \multirow{2}{*}{**Coke\({}^{\text{\textregistered}}\)**} & & H & 0.925 & 0.124 & 0.678 & 1.172 \\  & & T & 0.973 & 0.099 & 0.776 & 1.169 \\  & & S & 1.005 & 0.108 & 0.790 & 1.220 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Mean \(\Delta\)E values with their 95% confidence interval for all materials in four coloring solutions in all immersion periods. Distilled water was the control solution. H = heat-polymerized resin; T = 3D-printed hard PMMA resin; S = 3D-printed Urethane-based soft resin.