Assessment of Color Reproduction and Translucency of Monolithic All Ceramic Crowns of Three Margin Configurations using Two Different Cements
Fady Bassily Wadie Bassily;
Abstract
This study was designed to evaluate the effect of different margin configurations and different cement types on the color reproduction and translucency of monolithic translucent zirconia and lithium disilicate crowns.
Three stainless steel dies were designed to simulate all ceramic full coverage crown preparation for an upper premolar tooth. Three different margin designs were prepared: knife edge, chamfer and radial shoulder. An occlusal bevel was prepared for exact positioning of the copings during cementation and measurements.
Sixty full contour crowns were designed on the scanned stainless steel dies, ten for each margin design, using inLab 3D software (V3.8), and then were milled using translucent zirconia blocks and lithium disilicate blocks ( 30 crowns each).
The translucent zirconia crowns were milled with an oversize of approximately 25% to compensate for the later sintering shrinkage. Then the crowns were dyed to the shade A2 using the dipping technique, then sintered in high temperature furnace to have maximum density. The lithium disilicate crowns were adjusted in the pre-crystallized state and then were glazed and crystalized.
For the purpose of color and translucency measurements, black, white and tooth colored composite dies were constructed.Impressions of the master dies were made with a vinyl polysiloxane impression material . Then the impressions were injected with composite resin material (shade A2) to simulate tooth colored background.Six white Teflon dies and six stainless steel dies (two for each finish line design) were also milled according to the same criteria with the stainless steel dies sprayed in black. Those black and white dies were used for the purpose of translucency measurement.
Measurements of color and translucency were performed using Vita EasyShade Compact . Each sample was measured against the tooth colored compositedie and then against both the black and the white dies. The tip of the Vita EasyShade Compact was placed perpendicular to the middle third of the buccal surface. The EasyShade device was calibrated before every group measurement in order to standardize the reproducibility. CIE Lab values were calculated. Then the color difference (ΔE), the contrast ratio (CR) and the translucency parameter (TP) were calculated.
In order to test the effect of the cement on the color and translucency, measurements with the same criteria were performed after application of a thin layer of cement. Two types of cements were used, resin cement and glass ionomer cement.A thin layer of separating medium was brushed over each die and on the fitting surface of each crown to allow easy separation between them. A new cement capsule was used for the measurement of each sample.
Three stainless steel dies were designed to simulate all ceramic full coverage crown preparation for an upper premolar tooth. Three different margin designs were prepared: knife edge, chamfer and radial shoulder. An occlusal bevel was prepared for exact positioning of the copings during cementation and measurements.
Sixty full contour crowns were designed on the scanned stainless steel dies, ten for each margin design, using inLab 3D software (V3.8), and then were milled using translucent zirconia blocks and lithium disilicate blocks ( 30 crowns each).
The translucent zirconia crowns were milled with an oversize of approximately 25% to compensate for the later sintering shrinkage. Then the crowns were dyed to the shade A2 using the dipping technique, then sintered in high temperature furnace to have maximum density. The lithium disilicate crowns were adjusted in the pre-crystallized state and then were glazed and crystalized.
For the purpose of color and translucency measurements, black, white and tooth colored composite dies were constructed.Impressions of the master dies were made with a vinyl polysiloxane impression material . Then the impressions were injected with composite resin material (shade A2) to simulate tooth colored background.Six white Teflon dies and six stainless steel dies (two for each finish line design) were also milled according to the same criteria with the stainless steel dies sprayed in black. Those black and white dies were used for the purpose of translucency measurement.
Measurements of color and translucency were performed using Vita EasyShade Compact . Each sample was measured against the tooth colored compositedie and then against both the black and the white dies. The tip of the Vita EasyShade Compact was placed perpendicular to the middle third of the buccal surface. The EasyShade device was calibrated before every group measurement in order to standardize the reproducibility. CIE Lab values were calculated. Then the color difference (ΔE), the contrast ratio (CR) and the translucency parameter (TP) were calculated.
In order to test the effect of the cement on the color and translucency, measurements with the same criteria were performed after application of a thin layer of cement. Two types of cements were used, resin cement and glass ionomer cement.A thin layer of separating medium was brushed over each die and on the fitting surface of each crown to allow easy separation between them. A new cement capsule was used for the measurement of each sample.
Other data
| Title | Assessment of Color Reproduction and Translucency of Monolithic All Ceramic Crowns of Three Margin Configurations using Two Different Cements | Other Titles | قياس تطابق اللون و درجة الشفافية للتيجان المتآلفة الخزفية باستخدام ثلاث نماذج حافية مختلفة و نوعين مختلفين من اللواصق | Authors | Fady Bassily Wadie Bassily | Issue Date | 2014 |
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