الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 161 |  |  |
| | | from | 161 | | |
Abstract
The aim of the present study is to evaluate and compare The marginal fit before and after porcelain application and the porcelain shear bond strength of cast and Captek ceramometal systems. A specially designed cast nickelchromiumberyllium die resembling maxillary right central incisor was constructed. Twenty specimens, ten of each ceramometal system were obtained. The marginal openings were measured on the die before and after porcelain application at three predetermined index marks [ middistal, midlabial and midmesial ] for each specimen using a universal measurescope. Two specially designed stainless steel templates and a stainless steel sheet were used for the fabrication of ten wax patterns measuring 5 X 5 mm and 1 mm in thickness and then cast in a gold alloy. An Instron universal testing machine was used to test the specimens and a specially designed unibevelled chisel and holding device were used to direct the forces on the bonded surface. 1. There were significant differences between the marginal openings of the cast and the Captek specimens before and after porcelain firing. 2. The marginal openings of the cast specimens increased significantly after porcelain firing. 3. The marginal openings of Captek copings revealed no significant changes after porcelain firing. 4. The shear bond strength of the Captek specimens was significantly greater than the shear bond strength of the cast specimens.