# Influence of Food Pigments and Thermal Aging on the Color Stability of Denture Base Resins
## 3 Results  
Comparisons of \(\Delta\)E among resins after thermocycling (between T0 and T1) are summarized in Table 2 and Figure 13. Regarding the effect of thermocycling on the color changes of specimens, statistically significant color differences were observed regardless of the resin type (\(p<0.001\)), as shown in Table 2. However, comparisons among resins did not reveal statistically significant differences (\(p=0.376\)) (Figure 13). The color changes resulting from the subsequent immersion of the specimens in different beverages can be observed in detail in Table 3 and Figure 14. In Table 3, the multiple comparisons (MCs) row includes only the pairs of categories with statistically significant differences. It was observed that comparisons between beverages showed statistically significant differences, regardless of the resin type (\(p<0.05\)). Regarding the multiple comparisons between beverages, a similar trend was observed across the various resin groups. Immersion in red wine caused significantly greater color changes compared to water (\(p<0.05\)) for all resins and compared to the carbonated soft drink (\(p<0.05\)) for the Rapid V4 and S V4 resins. No statistically significant differences were observed between coffee and red wine. However, specimens immersed in red wine presented the highest \(\Delta\)E values, regardless of the resin type. With respect to comparisons between resins within each beverage category, no statistically significant differences were observed, although the results approached the significance level for specimens immersed in water (\(p=0.051\)) and red wine (\(p=0.064\)). In both red  
Figure 13: Box plots of \(\Delta\)E (T1–T0) by Villacryl resin category after thermocycling. (\({}^{\circ}\) represents outliers). \begin{table}
\begin{tabular}{c c c c c c} \hline  & & \multicolumn{3}{c}{\(\Delta\)E (T2–T1) \(\bar{\chi}\) (s)} \\ \hline
**Beverage** & **Plus V2** & **Plus V4** & **Rapid V4** & **S V4** & \(p\) \\ \hline Coffee (C) & 1.08 (0.66) & 1.19 (0.52) & 1.51 (0.57) & 1.21 (0.34) & 0.493 \\ \hline Red wine (W) & 2.54 (0.69) & 2.98 (0.4) & 2.18 (0.31) & 2.11 (0.47) & 0.064 \\ \hline Carbonated soft drink (CC) & 0.61 (0.24) & 1.02 (0.41) & 0.61 (0.54) & 0.66 (0.18) & 0.187 \\ \hline Water (A) & 0.36 (0.22) & 0.93 (0.48) & 0.35 (0.28) & 0.64 (0.25) & 0.051 \\ \hline \(p\) & 0.004 & 0.013 & 0.002 & 0.002 & \\ \hline Multiple comparisons & A-W & A-W & A-W, CC-W & A-W, CC-W & \\ \hline \end{tabular}
\end{table} 
Table 3: Comparisons of \(\Delta\)E (T2–T1) between Villacryl resin and beverage categories after immersion in the beverages (\(\bar{\chi}\): sample mean, s: sample standard deviation. C: coffee, W: wine, CC: carbonated soft drink, A: water). wine-immersed and water-immersed specimens, the Plus V4 resin recorded the highest color changes (2.98 \(\pm\) 0.4 and 0.93 \(\pm\) 0.48, respectively). Table 4 presents the NBS units corresponding to the color differences observed after thermocycling (between T0 and T1). All specimens exhibited perceivable differences, except for the specimens of the Rapid V4 resin, where the color difference was classified as \"slight\". The NBS units corresponding to color changes after immersion in beverages (between T1 and T2) and their critical points are presented in Table 5. It was observed that all specimens immersed in wine exhibited \"perceivable\" color changes, regardless of the resin type. Some groups showed \"extremely slight\" color changes, specifically the specimens immersed in water from the Plus V2 and Rapid V4 resins. The remaining specimens exhibited \"slight\" color changes. \begin{table}
\begin{tabular}{c c c} \hline
**Villacryl Resin** & **NBS Units** & **Color Changes** \\ \hline Plus V2 & \(1.51\) & perceivable \\ \hline Plus V4 & \(1.6\) & perceivable \\ \hline Rapid V4 & \(1.44\) & Slight \\ \hline S V4 & \(1.67\) & perceivable \\ \hline \end{tabular}
\end{table} 
Table 4: NBS units and color changes according to resin category after thermocycling (T0–T1).