Does Exposure to Daylight Affect the Coloration of the Composite?

Objectives: This study aims to investigate the color change of a composite material exposed to daylight. The objective is to simulate the clinical scenario where the lid of the composite box remains open during application. Additionally, the study aims to assess the impact of the polishing process on color change after composite discoloration in coffee immersion.
Methods: Disk shaped composite samples were prepared after exposure to daylight in a clear sunny day for 2, 4 and 6 minutes. Also a control group was utilized. A total of twenty-eight disc-shaped composite samples (NeoSpectra ST, Dentsply Sirona, Germany) were prepared. All samples were hydrated in distilled water at 37°C for 24 hours, and initial color measurements were recorded (T0) with a spectrophotometer. The control group remained in water, while the other groups were immersed in a coffee solution to simulate staining. After seven days, color measurements were repeated (T1), and color differences (ΔE using CIEDE2000) were calculated. Sof-Lex discs (3M ESPE, USA) were then used to polish all colored samples following the manufacturer's recommendations. Color measurements were repeated again (T2). Data were analyzed using Shapiro-Wilk and One-Way ANOVA with Tukey Post-Hoc Tests.
Results: All test samples showed a statistically significant color change compared to the control group after staining. However, no statistically significant color change was observed between the daylight exposure groups. The polishing process significantly reduced discoloration (p<0.001). After polishing, no statistically significant color difference was observed between the groups, although the polishing process was least effective in the 6-minute group.
Conclusions: Daylight exposure for tested periods before polymerization did not significantly affect the degree of coffee staining. The polishing process effectively removed composite discolorations however all groups except the control exhibited clinically unacceptable color changes compared to their initial state.