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Abstract This study aimed to evaluate three systems used to produce dental crowns; gold electroforming system GES, In-ceram alumina all ceramic system and the conventional metal ceramic system using gold alloy. Laboratory evaluation aimed to evaluate the shear bond strength SBS between veneering porcelain and underlying structure through making disc shaped specimens from the core materials and veneering porcelain in the form of rods. The change in color between intended shade guide and the resulted one, the marginal and internal fit of the tested systems was conducted through making 10 crowns of each system. The color change was evaluated using a recently introduced intraoral spectrophotometer, the marginal fit prior and after cementation was measured using a travelling microscope and sectioning of crowns was done to study the internal fit of each crown. The second part of the study aimed to evaluate 15 produced restorations clinically. Results of the study revealed that the shear bond strength between the veneering porcelain and underlying structure was significantly different among the three tested groups, with the gold alloyceramic restoration showing the highest values (31.7 MPa) , followed by the GES ( 24.9 MPa) and finally the In-ceram alumina ( 17.8 MPa). The change in color between the intended shade (2M2 -3D-master ) and the resulted color showed Delta E of 1.56 for the metal ceramic, 1.21 and 1.23 for the GES and Inceram alumina all-ceramic respectively. Marginal and internal fit showed high significant difference between the three tested groups with the GES showed the least marginal and internal gaps followed by the metal ceramic and the In-ceram alumina respectivley. Clinical evaluation of the three systems showed a 100 % survival for metal ceramic crowns, 80 % for both the GES and the In-ceram Alumina during a period of 17 months. It was concluded that the metal ceramic and the GES produced acceptable shear bond strength to the veneering porcelain. While the In-ceram showed values less than the acceptable ones. The change in color for the three groups falls within the clinically acceptable range. |