The use of monolithic reinforced ceramic restorations (lithium disilicate and zirconia-reinforced lithium silicate) is preferred to bilayered zirconia-based restorations to avoid chipping of the ceramic veneer.

No abstract

To evaluate the colour stability and surface roughness of 3 different CAD/CAM materials (IPS e.max, Vita Enamic, and PEEK) after immersion in two beverage solutions (Coffee, Coca-Cola). Methodology: Samples from a lithium disilicate glass-ceramic (IPS e.max CAD), a hybrid ceramic (Vita Enamic), and PEEK (BioHPP) were evaluated for colour change and surface roughness under immersion in two beverage solutions (Coffee, Coca-Cola). A total of 30 samples were prepared n=10 each. Spectrophotometer analysis was used to measure colour parameters (a*, b*, c*) before and after the immersion cycles and the average colour difference (Delta E*) was calculated after immersion in different beverages. Surface roughness was measured with a non-contact profilometer. Statistical analysis was performed using the Kruskal Wallis test with the Mann Whitney test as posthoc. The significance level was set at P ≤ 0.05. Results: There was a significant colour change between the materials. Vita Enamic and PEEK samples showed the highest colour change value with coffee immersion (ΔE) (7.96± 3.86), (6.07± 3.12) respectively. While IPS e.max. CAD revealed the lowest colour change value (2.62 ±1.54) following coffee immersion with a statistically significant difference in between (P< 0.011). After immersion in different media, there was a significant difference in surface roughness between the materials (p< 0.05). Conclusion: Vita Enamic and PEEK showed colour change beyond the clinically acceptable level, while IPS e.max CAD was the most stable material in colour and surface roughness.

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).

The aim of this study was to evaluate the survival of laminate veneers constructed using a recent polymer-infiltrated ceramic network material following the aesthetic pre-evaluative temporary (APT) technique of tooth preparation in comparison to traditional technique. Six patients received 54 laminate veneers. They were divided into two equal groups (n=27) according to the technique of tooth preparation: group T: traditional technique and group A: aesthetic pre-evaluative temporary technique. VITA ENAMIC material was used for CAD/CAM construction of laminate veneers. Cementation was performed using a light cured resin cement. The laminate veneers were evaluated at baseline, after 3, 6 and 12 months according to the modified United States Public Health Service (USPHS) criteriea. The data was collected, tabulated and statistically analyzed. Secondary caries, endodontic complications, cracks and loss of retention were not noted in any laminate veneer. Extensive fractures were not detected in both study groups through the study period. There was a statistically significant decrease of color match criteria between the two groups at the 6 and 12 months recalls. Based on this study, both preparation techniques resulted in successful clinical performance. After 12 months, all the veneers in both groups showed no post-operative sensitivity and all patients were highly satisfied regarding their veneers. However, there was a deterioration in color match criteria through the study period in both study groups.