Mennatallah Mohieeldin Wahba Alyeldin Mohamed

Tarek Salah Morsi

05/01/2023

https://link.springer.com/article/10.1007/s00784-022-04829-8

Mennatallah Mohieeldin Wahba Alyeldin Mohamed

Sahar H. Fikry; Tarek Salah Morsi, Amr S. Eletreby

01/06/2022

https://digitalcommons.aaru.edu.jo/fdj/vol8/iss1/11/

Mennatallah Mohieeldin Wahba Alyeldin Mohamed

Tarek Salah Morsi

01/06/2019

Objective: Despite the higher translucency of nano-crystalline Y-TZP than the conventional Y-TZP, it couldn’t be used in the anterior region of the mouth in its fully anatomical form without veneering for better esthetics. This study evaluated the color change (ΔE) and translucency parameter (TP) of the bilayered nano-crystalline zirconia restorations after different treatments of the zirconia surface before and after accelerated aging. Material and Methods: Forty samples of inCoris TZI were cut in the form of discs 15 mm (diameter) and 1mm (thickness) so that after sintering each disc dimensions’ would be 12 mm (diameter) and 0.8 mm (thickness). All discs were colored by dipping in aqueous zirconia coloring solution of shade A2, then divided into four groups according to the type of surface treatment received before sintering; being tribochemical silica coating, zirconia powder deposition, glass grading, and a control untreated group. After sintering, all discs were veneered with a layer of porcelain 0.7 mm (thickness) and 12 mm (diameter). (ΔE) and TP were measured using VITA Easyshade Compact spectrophotometer before and after accelerated autoclave aging. Results: Different surface treatments applied had significant effect (P<0.05) over ΔE and TP. Glass graded group showed the highest ΔE value and the least TP value among both un-aged and aged sub-groups. Conclusion: Different surface treatments applied affected the color and translucency negatively where the control untreated group showed the highest TP and the least color deviation from the A2 color parameters. On the other hand, accelerated autoclave aging had no effect over translucency or color.

Mennatallah Mohieeldin Wahba Alyeldin Mohamed

Tarek Salah Morsi

01/06/2018

Statement of problem The introduction of partially stabilized zirconium dioxide to the dental field created a path for development of new designs and applications, but still, a minimum framework thickness of 0.5 mm with the remaining thickness of the restoration used for building the ceramic veneer was always recommended. This might have possibly affected the final shade of the restorartion due to the whitish color of Y-TZP. Purpose This in vitro study was designed to evaluate the color reproduction ability of CAD-veneered zirconia restorations through the effect of different core-veneer thickness ratios and different translucencies of the Cad-on veneering material. Methods Sixty CAD-On restorations were constructed and classified into 3 groups (n = 20) of different core/veneer thickness ratios (0.5:1 mm, 0.7:0.8 mm, 1:0.5 mm). Each group was subdivided into 2 sub-groups (n = 10) according to the CAD-On veneer translucency (High Translucency HT, Low Translucency LT). Cad-On restorations were constructed using the CEREC InLab CAD/CAM System. Color change (ΔE) between groups of the CAD-On restorations was measured using Vita EasyShade Compact. All data was statistically analyzed and presented as mean and standard deviation values. Repeated measurements of data were analyzed with analysis of variance (ANOVA) for significant differences. Results There was significant difference (P < 0.05) for varrying the core/veneer thickness ratio over (ΔE) while both the veneer translucency and interaction between the core/veneer thickness ratio and veneer transluency had no significant effect. Conclusion There was a visually perceptible color change for all core/veneer thickness ratios and all veneer translucencies, but they were all in the clinically acceptable range.

Mennatallah Mohieeldin Wahba Alyeldin Mohamed

Tarek Salah Morsi

01/06/2017

Statement of problem With zirconia being chalky white in color with poor optical properties, several veneering techniques have been adopted to improve the esthetic qualities of zirconia-based restorations. Yet, these techniques didn't recommend the optimum combination of core-veneer thickness ratios and veneer translucency needed to provide the ultimate optical properties. Purpose This in vitro study was designed to evaluate the translucency of CAD-veneered zirconia restorations through the effect of different core-veneer thickness ratios, and different translucencies of Cad-On veneer material. Methods Sixty CAD-On restorations were constructed and classified into 3 groups (n = 20) of different core/veneer thickness ratios (0.5:1 mm, 0.7:0.8 mm, 1:0.5 mm). Each group was subdivided into 2 sub-groups (n = 10) according to the CAD-On veneer translucency (High Translucency HT, Low Translucency LT). Cad-On restorations were constructed using the CEREC InLab CAD/CAM System. Translucency of the CAD-On restorations was measured through 2 methods; relative translucency expressed in terms of contrast ratio (CR) using Vita EasyShade Compact and absolute translucency using Unicam spectrophotometer Helios. All data was statistically analyzed and presented as mean and standard deviation values. Repeated measurements of data were analyzed with analysis of variance (ANOVA) for significant differences. Results There was significant difference (P < 0.05) only for the effect of veneer translucency over the contrast ratio values, while with the core/veneer thickness ratio and interaction between veneer translucency and core/veneer thickness ratio had no significant difference over the contrast ratio values. For absolute translucency, there was significant difference (P < 0.05) for the effect of core/veneer thickness ratio, veneer translucency and interaction between them. Conclusions Only veneer translucency had significant effect over contrast ratio values, while on the other hand, absolute translucency values were significantly affected by the core/veneer thickness ratio, veneer translucency and interaction between them. It was clear that absolute translucency measurements showed higher translucency values for the restorations than contrast ratio measurements.