Effect of core and veneer thicknesses on the color parameters of two all-ceramic systems.
BACKGROUND
Specific contributions of the core and the veneer thickness on the appearance of layered disk specimens are not well characterized.


OBJECTIVE
This study examined the effect of varying core and veneer thickness on the color parameters of layered disk specimens made of 2 ceramic systems.


METHODS
Disk specimens 16 mm in diameter with core/veneer thickness (mm) of 0.8/0.2 (baseline), 0.8/0.7, 0.8/1.2, 1.0/0.5, 1.3/0.2, and 1.8/0.2 were made from a leucite-reinforced ceramic (IPS Empress; 2B shade), and thickness (mm) of 0.5/0.5 (baseline), 0.5/1.0, 0.5/1.5, 0.8/0.7, 1.0/0.5, and 1.5/0.5 were made from a glass-infiltrated spinell ceramic (In-Ceram Spinell; A2 shade). Color parameters L*, a*, and b* of CIELAB color space were measured against a neutral gray background with a tri-stimulus colorimeter, and deltaE between disk group and its respective baseline group was calculated. Analysis of variance was used to determine the effect of material and core and veneer thickness on the color parameters (alpha = .05).


RESULTS
Increasing the total disk thickness resulted in decrease of L* (P < .001) and an increase of a* (P < .001), b* (P < .001), and deltaE (P = .0236). For leucite-reinforced ceramic, the core thickness, veneer thickness, and their interaction exhibited significant influence on the mean values of a* and b* (P < .0028) but not on the mean values of L*. For spinell ceramic, the core thickness and veneer thickness exhibited significant influence on the mean values of L* and b* (P < .0272) but not on a*; the interaction demonstrated significant influence on b* (P = .0003) but not on L* and a*.


CONCLUSIONS
The color appearance of the layered ceramic disk specimens is strongly influenced not only by the core thickness and veneer thickness, but also by their interaction.
Shokry
Tamer E
TE
Department of Fixed Prosthodontics, Faculty of Dental Medicine, Al-Azhar University, Egypt.
Shen
Chiayi
C
Elhosary
Mohamed M
MM
Elkhodary
Adel M
AM
D000537:Aluminum Oxide; D000538:Aluminum Silicates; D000704:Analysis of Variance; D003116:Color; D003442:Crowns; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D003801:Dental Veneers; D016014:Linear Models; D008277:Magnesium Oxide; D008422:Materials Testing; D017797:Prosthesis Coloring
D000538:Aluminum Silicates; C075815:IPS-Empress ceramic; C111130:spinell; D003776:Dental Porcelain; C078519:leucite; D008277:Magnesium Oxide; D000537:Aluminum Oxide