An in Vitro Study to Evaluate the Color Stability of Four Different Cad/Cam Ceramics

Abstract

Statement of the problem: Dental Ceramics have been widely used in patients seeking ultimate esthetics, however still there is concern about their color stability by time. Aim of the study: To evaluate the color stability of four different CAD/CAM ceramics after immersion in coffee solution. Materials and Methods: A total of twenty ceramic discs with shade A2 (10 mm in diameter and 2mm in thickness) were constructed in standardized manner. Samples were divided into four main equal groups (n=5) each, according to the type of ceramic material used. Group I: IPS e.max CAD. Group V: Vita Suprinity. Group C: Cerec Blocs. Group O: Obsidian. All specimens were fabricated using CNC milling machine and electric isoMet microsaw 4000. A specially constructed cylindrical split teflon mold was fabricated for the construction of twenty composite resin discs shade A3 (10 mm in diameter and 2mm in thickness). Both ceramic and composite discs were constructed according to manufacturer instructions then were adhesively luted using dual cure Rely X U200 Automix self-Adhesive resin cement shade A2 under 2 Kg constant load application. All disc samples were immersed in coffee solution for 3 weeks and were tested twice; before (baseline) and after the immersion. The color of each sample was then assessed using a spectrophotometer. The L* a* b* values of the samples were recorded according to the CIELAB color scale relative to the standard illumination D65. The results were tabulated and statistically analyzed as mean, standard deviation (SD), median, range and with 95% Confidence interval values. For parametric data, one-way ANOVA was used followed by Tukey's post-hoc test to compare between the four groups. While for non-parametric data, Kruskal-Wallis test was used to compare between the four groups. The significance level was set at P ≤ 0.05. Statistical analysis was performed with IBM® SPSS® Statistics Version 20 for Windows. Results: There was a statistically significant difference between the four ceramic groups after immersion in coffee solution. A decrease in (L*) values was found in all groups. Pair-wise comparisons revealed that IPS e.max CAD showed the highest mean decrease in (ΔL) (-5.19±0.71).

Color Stability of three esthetic monolithic block materials after immersion in commonly consumed beverages

“…During the polishing process, the thickness of the samples was repeatedly evaluated until the final thickness of 2 mm was achieved. 3,16,23,[33][34][35]…”

“…A white background was chosen, and measurements were taken in relation to the CIE standard illuminant D65 according to the CIE L*a*b* color space. 1,4,8,23,25 Measurements were done for each group before and after immersion in each solution to produce ΔL*, Δa * and Δb* that represent the differences in the respective coordinates. The color changes (ΔE) of the specimens were evaluated using the following formula:…”

“…The resistance of these CAD/CAM monolithic esthetic materials to staining over time is decisive for the success and longevity of such restorations, especially in harsh oral environment conditions. 1,3,4,23,24 Commonly consumed beverages such as coffee and cola often contain colorants or impose acidic pH that may adversely affect esthetic restorations causing discoloration. 4,23,25 Discoloration could be caused by either extrinsic or intrinsic factors.…”

“…1,3,4,23,24 Commonly consumed beverages such as coffee and cola often contain colorants or impose acidic pH that may adversely affect esthetic restorations causing discoloration. 4,23,25 Discoloration could be caused by either extrinsic or intrinsic factors. Extrinsic factors include surface roughness, smoking and exposure to stain-producing beverages and colored solutions.…”

“…3,19,26 COLOR STABILITY OF ESTHETIC MONOLITHIC MATERIALS (3763) The color change can be accurately evaluated using the CIE L*a*b* system, which proved its efficiency in determining minute color changes, in addition to its sensitivity and reproducibility. 3,23,27,28 The CIE Lab system is developed by the Commission of Internationale de l'Eclairage (CIE), where, L* represents lightness and takes a value between 0 (black) and 100 (white). a* represents the saturation on the red-green axis, and b* represents the saturation on the yellow-blue axis.…”