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Purpose: Objectives of this study were to assess and compare the impact of coloring beverages and surface finishing on color stability and surface roughness of dental ceramics.Material and methods: Twenty-eight identical cuboids (14*12*1mm) were cut from zirconiareinforced lithium silicate blocks (suprinity) using a precision cutting machine. Another 28 identical cuboids with the same dimensions were milled from high translucent zirconia ceramic blank (zolid fx). The specimens of each ceramic material were divided into 2 main groups (n=14) according to the finishing technique used; group G: specimens were glazed. group P: specimens were polished. Each subgroup was subdivided into 2 subgroups (n=7) according to the immersion solution used; Tea or Cola. Color measurements and surface roughness of all specimens were measured at the beginning and after 28 days of immersion in the staining beverages.Results: Tea possessed the highest color changes in all tested groups, and these changes were statistically significant compared with those of Cola in both surface finishing groups and in both types of ceramics. The color changes of Tea were not clinically acceptable in the zirconia ceramic groups (ΔE ˃3.3).While Cola possessed the highest mean Ra in all tested groups, and these changes were statistically significant compared with those of Tea in both surface finishing groups and in both types of ceramics. Conclusions:Tea showed the highest impact on color of polished and glazed types of used ceramics, while Cola significantly increased the surface roughness of both polished and glazed types of used ceramics.

PURPOSE. This study aimed to evaluate the bond strength of two resin cements to lithium disilicate ceramic after different etching and priming protocols. MATERIALS AND METHODS. 64 lithium disilicate discs (IPS e.max press) were fabricated by pressing technique then divided into two groups (n=32) group (I) multi-step adhesive resin cement (Multilink® N); group (II) self-adhesive resin cement (Maxcem Elite®). Each group was subdivided into four subgroups (n=8) according to surface treatment material; (A): Monobond Etch & Prime, (B): Hydrofluoric acid, (C): Acidulated phosphate fluoride (D): Ammonium hydrogen difluoride. Composite resin discs (Nexcomp®) were cemented to treated ceramic discs. All bonded specimens stored in water bath for 5 months and subjected to 5000 thermal cycles. Shear bond strength (SBS) test was performed using a universal testing machine. Scanning Electron Microscope (SEM) was used for specimens' examination. RESULTS. Statistical analysis were done using twoway ANOVA and serial one-way ANOVAs followed by Post Hoc Tukey-HSD test at α =0.05. The highest SBS mean value 17.05±3.99 MPa, 16.59±2.27 MPa was obtained for APF and HF at multi-step adhesive cement. On the other hand, AHDF with self-adhesive resin cement showed the lowest SBS mean value 6.71±1.46 MPa. There was statistically significant difference between AHDF and other used materials. CONCLUSION. Multi-step adhesive resin cement showed superior bond strength than selfadhesive resin cement. Also, HF acid and APF were preferred to be used more than Monobond Etch & Prime for ceramic surface treatment as they significantly affected the durability & bond strength regardless used cement type.

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