AN IN VITRO STUDY TO EVALUATE THE COLOR STABILITY OF FOUR DIFFERENT CAD/CAM CERAMICS

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).