Moon-Sang Cho1, Bin Yu, Yong-Keun Lee. 1. Department of Dental Biomaterials Science and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
Abstract
OBJECTIVES: The enamel of natural teeth is opalescent, where there is light scattering of the shorter wavelengths of the visible spectrum, giving a tooth a bluish appearance in the reflected color and an orange/brown appearance in the transmitted color. The objective of this study was to determine the opalescence of all-ceramic core, veneer and layered specimens with a color measuring spectrophotometer. METHODS: Colors of core (A2-corresponding shade), veneer (A2- and A3-corresponding shades) and layered (A2- and A3-layered) ceramics for all-ceramic restorations in clinically relevant thicknesses were measured in the reflectance and transmittance modes. The opalescence parameter (OP), which was calculated as the difference in blue-yellow coordinate (Deltab(*)) and red-green coordinate (Deltaa(*)), and the differences in blue-yellow coordinate (Deltab(*)) and in color (DeltaE(ab)(*)) between the reflected and transmitted colors were calculated. One-way ANOVA was performed for the OP values of the core, veneer and layered specimens by the kind of materials. Regression analysis was performed between the OP and Deltab(*), and the OP and DeltaE(ab)(*) values. RESULTS: The range of the OP value was 1.6-6.1, 2.0-7.1, 1.3-5.0 and 1.6-4.2 for the core, veneer, A2- and A3-layered specimens, respectively, all of which were significantly influenced by the kind of materials (p<0.05). The OP and DeltaE(ab)(*) values showed significant correlations within each of the core and veneer ceramics. SIGNIFICANCE: Opalescence varied by kind of ceramics. The OP values of ceramics were lower than those of tooth enamel. All-ceramic materials that can simulate the opalescence of natural teeth should be developed.
OBJECTIVES: The enamel of natural teeth is opalescent, where there is light scattering of the shorter wavelengths of the visible spectrum, giving a tooth a bluish appearance in the reflected color and an orange/brown appearance in the transmitted color. The objective of this study was to determine the opalescence of all-ceramic core, veneer and layered specimens with a color measuring spectrophotometer. METHODS: Colors of core (A2-corresponding shade), veneer (A2- and A3-corresponding shades) and layered (A2- and A3-layered) ceramics for all-ceramic restorations in clinically relevant thicknesses were measured in the reflectance and transmittance modes. The opalescence parameter (OP), which was calculated as the difference in blue-yellow coordinate (Deltab(*)) and red-green coordinate (Deltaa(*)), and the differences in blue-yellow coordinate (Deltab(*)) and in color (DeltaE(ab)(*)) between the reflected and transmitted colors were calculated. One-way ANOVA was performed for the OP values of the core, veneer and layered specimens by the kind of materials. Regression analysis was performed between the OP and Deltab(*), and the OP and DeltaE(ab)(*) values. RESULTS: The range of the OP value was 1.6-6.1, 2.0-7.1, 1.3-5.0 and 1.6-4.2 for the core, veneer, A2- and A3-layered specimens, respectively, all of which were significantly influenced by the kind of materials (p<0.05). The OP and DeltaE(ab)(*) values showed significant correlations within each of the core and veneer ceramics. SIGNIFICANCE: Opalescence varied by kind of ceramics. The OP values of ceramics were lower than those of tooth enamel. All-ceramic materials that can simulate the opalescence of natural teeth should be developed.
Authors: Marina R Kaizer; Ana Paula R Gonçalves; Priscilla B F Soares; Yu Zhang; Paulo F Cesar; Sergio S Cava; Rafael R Moraes Journal: Dent Mater Date: 2016-01-02 Impact factor: 5.304