Abstract
Objective:
This study aimed to assess the color stability of omnichroma composite resin after immersion in coffee, cola and iced tea.
Methods:
A total of 30-disc shape specimens of omnichroma, 10mm diameter and 2mm thickness, were made in a Teflon mold. The samples were washed and stored in artificial saliva for 24 hours in a 37°C incubator. The top surfaces of specimens were polished with polishing disks (Sof-lex; 3M ESPE). Samples were divided randomly into 3 groups, and each group contained 10 discs. Groups were immersed in 15 ml of 3 different storage media (cola, iced tea and black coffee). Immersion groups were stored in an incubator at 37 °C. Color assessment was carried out by VITA Easy shade 2.0 spectrophotometer color assessment device according to the CIE L*a*b*system, against a gray background to measure baseline records for the samples. After 4 weeks, a second record was taken for the samples after they were gently rinsed with distilled water and dried. The experimental data were statistically evaluated using the Wilcoxon sign rank test with a significance level < 0.05%.
Results:
The highest color change was reported with coffee (ΔE=20.16) followed by cola (ΔE=19.6) and iced tea (ΔE=4.75).
Conclusion:
All assessed drinks resulted in discoloration of the shade less composite resin material above the clinically acceptable level (ΔE>3.3) after 30 days of immersion. Coffee has the highest staining among the three drinks, followed by cola, and then iced tea.

Key words: Color stability, Spectrophotometer, Omnichroma, Staining, Drinks.