Air abrasion has a greater effect than CO₂and Er,Cr:YSGG lasers in the treatment of zirconia ceramic surfaces to enhance the bonding strength of resin cement to zirconia. CO₂laser at 4W and Er,Cr:YSGG laser at only 3-W output power can be regarded as surface treatment options for roughening the zirconia surface to establish better bond strength with resin cements.

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Background: Color change is one major drawback of tooth-colored resin-based restorations. Objectives: This study aimed to assess the color stability of three commonly used resin-based restorative materials upon exposure to tea and coffee. Materials and Methods: Discs were fabricated from Spectrum TPH (Dentsply/Caulk), Denfil (Vericom), and Filtek Z250 (3 M) microhybrid composites and immersed in coffee and tea solutions for two hours on the first day and the whole of the second, third, and fourth days. The color was assessed visually and recorded using the Lobene Stain Index after each period of immersion. The color change of the three composite resins was compared using the Kruskal-Wallis test, Mann-Whitney U test, and Friedman test. The level of significance was set at 0.05. The Cohen's Kappa was also calculated to assess inter-rater agreement. Results: The three composite resins showed statistically significant color changes after four days of immersion in a coffee solution (P = 0.014), but their color change in the tea solution was not significant (P > 0.05). A comparison of color changes in the composites after one (two hours) and four days of immersion in tea and coffee solutions revealed a significant difference in color changes between Spectrum TPH and the other two composites (P < 0.001). Conclusions:The three microhybrid composites used in this study showed variable color stability upon exposure to a coffee solution. The color stability of Spectrum TPH was inferior to that of Denfil and Filtek Z250.