## 3 Results
### Color Change Results  
The means and standard deviations of \(\Delta\)E* in the control and AgNPs groups for all of the colors, including colorless, red, blue, mocha, and their mixtures, subjected to 250 h of artificial aging, are presented in Table 3. However, Table 4 displays the same findings for 500 h of artificial aging. An ANOVA table of the color alterations (\(\Delta\)E*) following the artificial aging is shown in Table 5. All evaluated specimens from the control and AgNP groups experienced a chromatic alteration (\(\Delta\)E* \(>\) 0). The \(\Delta\)E* values for all groups were found to be above the perceptible threshold (1.1 units), except for mocha with 0.2% AgNPs after 250 h of aging, where the \(\Delta\)E* value was below the perceptible threshold (\(\Delta\)E* = 0.97). However, \(\Delta\)E* was determined to be below the acceptable clinical threshold of 3.0 units, demonstrating acceptable aging-dependent color changes, except for red in all groups and blue in the control group after 500 h of aging.  
It is crucial to note that there were relevant variations in the \(\Delta\)E* values among the groups. For the colorless specimens, only the control group that underwent 500 h of aging showed a significant change (\(\Delta\)E* = 2.41 (0.22)) according to the perceptible threshold (\(p\) = 0.027). All other groups were over the perceptible threshold, but the differences were barely perceptible and were still below the acceptable threshold. After 250 and 500 h, all groups with and without AgNPs showed a highly significant change in the perceptible and acceptable threshold for red (\(p\) = 0.000). For the color blue, only the control group, after 500 h of aging, displayed a significant change (\(\Delta\)E* = 3.15 (0.44)) relative to the perceptible threshold (\(p\) = 0.000). The blue color with 0.2% AgNPs after 500 h of aging showed a significant decrease in color change (\(\Delta\)E* = 1.49 (0.28)) compared to the acceptable threshold (\(p\) = 0.002). According to the perceptible threshold (\(p\) = 0.019) for mocha, the control group aged for 500 h exhibited a significant change (\(\Delta\)E* = 2.44 (0.24)). However, it is essential to mention that the least color change for mocha was found for the 0.2% AgNPs subjected to 250 h of aging, which was found to be lower than the perceptible threshold (\(\Delta\)E* = 0 0.97 (0.23)). Based on the perceptible threshold for the mixed color (\(\Delta\)E* = 1.1), the control group underwent substantial changes after 250 and 500 h of aging (\(p\) = 0.048 and \(p\) = 0.001, respectively). Also, in terms of the perceptible threshold (\(p\) = 0.04), after 500 h, the mixed color containing 0.1 percent AgNPs (\(\Delta\)E* = 2.70 (0.26%)) altered dramatically. However, all of the groups were below the acceptable threshold (\(\Delta\)E* = 3.0).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Pigments**} & \multirow{2}{*}{**Control**} & \multicolumn{3}{c}{**AgNPs (\%)**} \\ \cline{3-5}  & & **0.1 AgNPs** & **0.15 AgNPs** & **0.2 AgNPs** \\ \hline Colorless & **1.98** (0.33) & **1.77** (0.47) & **1.67** (0.58) & **1.47** (0.28) \\ (Silicone only) & Red & **26.71** (2.24) & **14.03** (0.40) & **13.11** (0.35) & **11.65** (0.70) \\ Blue & **2.03** (0.40) & **1.71** (0.32) & **1.58** (0.39) & **1.12** (0.33) \\ Mocha & **1.41** (0.31) & **1.22** (0.29) & **1.17** (0.31) & 0.97 (0.23) \\ Mix & **2.36** (0.40) & **2.14** (0.36) & **2.05** (0.19) & **1.92** (0.24) \\ (Red + Blue + Mocha) & \multicolumn{3}{c}{Bolded numbers: \(\Delta\)E* \(>\) 1.1 (50:50% perceptibility threshold); bolded underlined numbers: \(\Delta\)E* \(>\) 3.0 (50:50% acceptability threshold).} \\ \hline \hline \end{tabular}
\end{table}
Table 3: Means and standard deviations of \(\Delta\)E* for control and AgNP groups after 250 h of aging.