Objective: Two types of tea and coffee were selected to examine the color stability of bulk fill and incremental fill resin composite after storage for one and seven days.
Materials and methods: A total of 150 resin composite discs (Filtek™ Z350), bulk fill (Xtra-fil) and (Filtek bulk) were prepared using a cylindrical mold (2x4). Ten specimens of each restorative material were left in distilled water for one day to be used for baseline color assessment. Then each tested material where either placed in black coffee, black tea, lemon ice tea or coffee milk beverages for one day or seven days inside an incubator at 36±1 °C. The relative spectral reflectance of each specimen was assessed using a spectrophotometer after storage in these beverages.
Results: Kruskal-Wallis statistical test showed that there is a statistically significant difference between the three tested restorative materials after storage for one day and after 7 days in all the storage beverages where (p < 0.05). At the two aging periods, Z350 showed the statistically significant highest ΔE, X-tra fil showed the lowest statistically significant ΔE, while there was no statistically significant difference in the mean values of ΔE of Filtek bulk and these two materials. Regarding the effect of storage beverages on each restorative material at the two storage periods, black tea caused the highest statistically significant ΔE, while coffee milk caused the lowest statistically significant ΔE in the three tested resin composite.