Background: Sometimes, porcelain restorations experience some degree of colour change in oral environment, which could be related to the quality of diet and surface roughness of these restorations. Objective: The aim of this in-vitro study was to evaluate the influence of Arabic-Coffee on the overall color of glazed or polished porcelain veneers fabricated from four different porcelain materials and two different thicknesses. Materials and Methods: A total of 160 porcelain disc of tested specimens were fabricated to a standardized thickness of 1.00 mm and 0.6mm using the following materials: Feldspathic porcelain, Zircon, E-max Press, and E-max CAD; (80 discs for each thickness and 20 specimens of each material used). Veneer specimens from each material were randomly divided into two subgroups (n = 10): 10 specimens were kept as glazed, were the other 10 tested specimens were adjusted with diamond burs, and then polished with Ivoclar Vivadent ceramic polishing kits using the recommended protocol for polishing provided by the company. A color of all tested specimens was measured using Vita Easy Shade Spectrophotometer. Then, all specimens were immersed in Arabic coffee (Al Mosafer Coffee, Saudi Arabia) and theromcycled for 1 week, and the colors of all tested specimens were then recorded again. Results: It was shown that there is a significant difference in the average color changes before and after immersing in Arabic-Coffee for all materials and thicknesses used in the current study. In-addition, significant differences in color changes were noticed between glazed and polished specimens. Moreover, colour change caused by the coffee was not significantly related to the thickness of the specimens used. Conclusion: Color stability of porcelain materials could be affected by surface treatment whether glazing or polishing. All aesthetic restorations should be deglazed whenever any adjustments have been done to maintain the color match and stability in an oral environment. Also, Arabic-Coffee is considered as a staining drink to a limited extend where patient should be assured to maintain their oral health to maintain the colour stability of their restorations.

Aim:The aim of the current study is to assess the influence of Coca-Cola drinks on the overall color of glazed or polished porcelain veneers fabricated of three different porcelain systems and two different thicknesses. Materials and methods: A total of 96 ceramic disk specimens were fabricated. The ceramic veneers were prepared to a standardized thickness of 1.0 mm ± 0.025 mm and 0.6 ± 0.025 (48 samples each group) using the following ceramic systems: Zircon, E-max press, and E-max CAD/CAM. Veneer samples from each system were divided into two subgroups (n = 8). First subgroup samples were glazed according to the manufacturer's instructions, and the other subgroup samples were adjusted with diamond burs then polished with ceramic polishing kit. Color was measured with Vita Easyshade spectrophotometer. Then all samples immersed with Cola drink, for 4 weeks, in a thermocycling machine and then the color were measured again and color change was recorded. Results: Significant differences in color change were noticed before and after immersing with Coca-Cola and thermocycling for all materials and thicknesses used (p < 0.01). Significant differences in color changes were noticed between glazed and polished samples (p < 0.001). No significant differences in color change were noticed when using different thicknesses for all materials used (p < 0.05). Conclusion: Different porcelain materials have shown significant color changes after immersing and thermocycling in Coca-Cola drinks. The color changes of polished porcelain specimens were more considerable than those of polished specimens for all porcelain materials and thicknesses used. This suggests reglazing of all esthetic restoration after any adjustments might be performed and before final cementation in an attempt to maintain the color stability in oral environment. Clinical significance: To achieve a perfect color stability of ceramic veneers, clinicians should take into consideration the possible color deviations that might result after any adjustment followed by polishing procedures to the ceramic surface. And, it is always preferable to do reglazing of porcelain restorations after any surface treatments and before final cementation.