All-ceramic Core Materials Research Articles

Difference in the translucency of all-ceramics by the illuminant

Objectives The objective of this study was to determine the differences in the translucency parameter (TP) of all-ceramic core, veneer and layered specimens relative to the CIE standard illuminant D 65, A and F2. Methods The A2-corresponding shade of seven all-ceramic core materials and one sintering ceramic as a reference were prepared in clinically relevant thicknesses ( n = 7). The A2- and A3-corresponding shades of each recommended veneer ceramics were fabricated so that the thickness of the layered specimen was 1.5 mm. The color of core, veneer and layered specimens was measured over white and black backgrounds relative to the illuminant D 65, A and F2 with a reflection spectrophotometer. TP value was obtained by calculating the color difference between the specimen over the white and that over the black background. Differences of TP values by the illuminant (ΔTP) were analyzed with three-way analysis of variance (ANOVA), with the fixed factors of the type of ceramic, the brand/thickness of ceramic within each type and the combination of illuminants ( α = 0.05). Results ΔTP values were influenced by three factors based on three-way ANOVA. Higher translucent materials showed higher difference in TP value by the illuminants. TP(D 65) was lower than TP(F2) and TP(A) values. Correlation coefficients between TP values relative to the different illuminants were higher than 0.994 ( p < 0.01). Significance Translucency of all-ceramic materials under daylight condition was lower than those under incandescent or fluorescent lamps. Therefore, this difference should be considered when shade matching translucent shades of all-ceramics.

Chromatic Study of All-ceramic Restorations: Relative Translucency of 9 All-ceramic Core Materials

Purpose: All-ceramic restorations are widely used in esthetic dentistry. Various materials have been used to improve ceramic core strength, but it is unclear whether they affect the opacity of all-ceramic systems. The aim of this study was to compare the translucency of 9 all-ceramic system core materials at clinically appropriate thickness.Materials and methods: A 360-degree round deep chamfer preparation for the all-ceramic crown was made for a maxillary right first molar tooth as the dental model. Coping of 0.5mm thickness were fabricated by Empress Esthetic (ETC1, EOC1, EO1, EO2), Empress2 (50) (IVOCLAR VIVADENT), Procera AllCeram, Procera AllZirkon (Nobel Biocare), LAVA (3M ESPE), and DentaCAD Systeme (Hint-Els). Abutments were made by black wax and white wax. Spectrophotometric measurements were made by a spectrophotometer. The final color of the central part of the buccal surface was measured and the L*a*b* color space was used to obtain the color values. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white (Yw) backing to give Yb⁄Yw with CIE illuminant D65 and 2-degree observer function (0.0=transparent, 1.0=opaque).Results: Contrast ratio in order of most translucent to most opaque were as follows: EO2 .41, EO1 .43, ETC1 .43 , EOC1 .44, Empress2 .50, AllCeram .63, AllZirkon .74, LAVA .76, DentaCAD.80. There was no significant difference(p<.05) between the AllZirkon, LAVA, DentaCAD or ETC1, EOC1, EO1, EO2.Conclusion: Within the limitations of this in-vitro study on 9 all-ceramic core systems, a significant range of translucency was identified across specimen groups.

Flexural strength and fracture toughness of dental core ceramics

Many different strengthened all-ceramic core materials are available. In vitro study of their mechanical properties, such as flexural strength and fracture toughness, is necessary before they are used clinically. The purpose of this study was to evaluate and compare the mechanical properties of 6 commonly used all-ceramic core materials using biaxial flexural strength and indentation fracture toughness tests. Specimens of 6 ceramic core materials (Finesse, Cergo, IPS Empress, In-Ceram Alumina, In-Ceram Zirconia, and Cercon Zirconia) were fabricated (n=25) with a diameter of 15 mm and width of 1.2 +/- 0.2 mm. For each group, the specimens were tested to compare their biaxial flexural strength (piston on 3 balls) (n=15), Weibull modulus, and indentation fracture toughness (n=10) (IF method). The data were analyzed with 1-way ANOVA test (a=.05). The Tamhane multiple comparison test was used for post hoc analysis. Mean (SD) of biaxial flexural strength values (MPa) and Weibull modulus (m) results were: Finesse (F): 88.04 (31.61), m=3.17; Cergo (C): 94.97 (13.62), m=7.94; IPS Empress (E): 101.18 (13.49), m=10.13; In-Ceram Alumina (ICA): 341.80 (61.13), m=6.96; In-Ceram Zirconia (ICZ): 541.80 (61.10), m=10.17; and Cercon Zirconia (CZ): 1140.89 (121.33), m=13.26. The indentation fracture toughness results showed that there were significant differences between the tested ceramics. The highest fracture toughness values (MPa x m(0.5)) were obtained with the zirconia-based ceramic core materials. Significant differences were found in strength and toughness values of the materials evaluated. Cercon Zirconia core material showed high values of biaxial flexural strength and indentation fracture toughness when compared to the other ceramics studied.

Layered color of all-ceramic core and veneer ceramics

Color of an all-ceramic restoration is the result of interaction between core and veneer ceramics. However, the influence on color of the different types of all-ceramic core and veneer combinations at clinically relevant thicknesses is not well understood. The purpose of this study was to measure the layered color of all-ceramic core and veneer combinations with the thickness of the core set as the clinically minimum thickness to mask the background, and the thickness of the veneer set as the remaining available thickness within a clinically allowable thickness. The A2-corresponding shade of 7 all-ceramic core materials, and 1 sintering ceramic and 1 alloy core as references, were prepared in clinically minimum thicknesses (0.4 to 0.8 mm) to mask the background (n=7). The A2 and A3 corresponding shades of each recommended veneer ceramic were used to fabricate specimens that were 1.5 mm thick. The color of the core, veneer, and layered specimens was measured with a reflection spectrophotometer. Two-way ANOVA with the independent variables of the types of core and veneer ceramics on the layered color was used to analyze the data (alpha=.05). The influence of the color coordinates in the core and veneering ceramics on the layered color was analyzed with multiple regression analysis. CIE L( *), a( *), b( *), and C( *)(ab) values of A2- or A3-veneer layered specimens were influenced significantly by the combination of core and veneer ceramics (P<.001). The CIE L( *) values of layered specimens were primarily influenced by the CIE L( *) values of the core ceramic (P<.001). The other 3 parameters were primarily influenced by each corresponding parameter of veneer ceramic, based on multiple regression analyses (P<.001). The layered color of all-ceramic core and veneer ceramics in the clinically allowable thickness was different even when the same shade, keyed to a VITA guide, of core and veneer ceramics were layered. The color difference between each pair of A2- or A3-veneered specimens by the combination of core and veneer ceramics ranged from 1.4 to 5.6 DeltaE( *)(ab) units.

オールセラミックレストレーションの色調に関する研究―支台歯色がコーピングの色調に及ぼす影響―

Recently, the use of all-ceramic crowns has spread widely in clinical applications to meet the demand for both functional and esthetically-pleasing restorations. In making all-ceramic crowns, it is necessary to reproduce the shape and color near to those of the natural teeth. However, the color shades of abutments might influence the color of the copings which are made of material with high transparency. This study examined the influence of the color shades of the abutments on the final color of copings for three kinds of all-ceramic core materials: Empress, Empress 2 (IVOCLAR VIVADENT), and Procera AllCeram (Nobel Biocare). Copings with 0.5 mm in thickness were fabricated by using Empress (TC1), Empress 2 (100), and Procera AllCeram (white) core materials for an upper-right central incisor. Abutments were made by using six kinds of die materials of the Empress system (ST1, ST2, ST3, ST5, ST8, ST9), gold-silver-palladium alloy, gold alloy, and experimental black body. Copings were inserted in each abutment and the final color of the central part of the buccal surface was measured using a spectrophotometer according to the L*a*b* color system. Regardless of the color shades of the abutments, the chroma values of the copings rose in the order of Empress, Empress 2, and Procera, and the values of lightness rose in the order of Empress, Procera, and Empress 2. When the final color of each coping measured under the wet and dry conditions were compared, the difference in chroma was great. Within the limitations of this study, the results suggest that the influence of the color shades of the abutments on the final color of the three kinds of copings is small in the order of Empress, Procera, and Empress 2. In clinical and dental laboratory operations, it is hoped to observe and measure the color of copings and restorations under the wet condition.

Relative translucency of six all-ceramic systems. Part II: Core and veneer materials

STATEMENT OF PROBLEM All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material. This study compared the translucency of 6 all-ceramic materials veneered and glazed at clinically appropriate thicknesses. Core specimens (n = 5 per group) of Empress dentin, Empress 2 dentin, In-Ceram Alumina, In-Ceram Spinell, In-Ceram Zirconia, and Procera AllCeram were fabricated as described in Part I of this study and veneered with their corresponding dentin porcelain to a final thickness of 1.47 +/- 0.01 mm. These specimens were compared with veneered Vitadur Alpha opaque dentin (as a standard), a clear glass disc (positive control), and a high-noble metal-ceramic alloy (Porc. 52 SF) veneered with Vitadur Omega dentin (negative control). Specimen reflectance was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Measurements were repeated after a glazing cycle. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white backing (Yw) to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P<.05). Significant differences in contrast ratios were found among the ceramic systems tested when they were veneered (P<.0001) and after the glazing cycle (P<.0001). Significant changes in contrast ratios (P<.0001) also were identified when the veneered specimens were glazed. Within the limitations of this study, a range of translucency was identified in the veneered all-ceramic systems tested. Such variability may affect their ability to match natural teeth. The glazing cycle resulted in decreased opacity for all test materials except the completely opaque In-Ceram Zirconia and metal-ceramic specimens.

Relative translucency of six all-ceramic systems. Part II: Core and veneer materials

Statement of Problem. All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material. Purpose. This study compared the translucency of 6 all-ceramic materials veneered and glazed at clinically appropriate thicknesses. Material and Methods. Core specimens (n = 5 per group) of Empress dentin, Empress 2 dentin, In-Ceram Alumina, In-Ceram Spinell, In-Ceram Zirconia, and Procera AllCeram were fabricated as described in Part I of this study and veneered with their corresponding dentin porcelain to a final thickness of 1.47 ± 0.01 mm. These specimens were compared with veneered Vitadur Alpha opaque dentin (as a standard), a clear glass disc (positive control), and a high-noble metal-ceramic alloy (Porc. 52 SF) veneered with Vitadur Omega dentin (negative control). Specimen reflectance was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Measurements were repeated after a glazing cycle. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white backing (Yw) to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P<.05). Results. Significant differences in contrast ratios were found among the ceramic systems tested when they were veneered (P<.0001) and after the glazing cycle (P<.0001). Significant changes in contrast ratios (P<.0001) also were identified when the veneered specimens were glazed. Conclusion. Within the limitations of this study, a range of translucency was identified in the veneered all-ceramic systems tested. Such variability may affect their ability to match natural teeth. The glazing cycle resulted in decreased opacity for all test materials except the completely opaque In-Ceram Zirconia and metal-ceramic specimens. (J Prosthet Dent 2002;88:10-5.)