الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
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Abstract
This study was conducted to compare and evaluate the influence of three post and core systems on the shade of all ceramic crowns by spectrophotometric analysis namely: zirconia post (cosmopost) with composite core, Cast metal post and core with opaque porcelain on the core and Cast metal post and core without opaque porcelain. Also to compare the fracture resistance of all ceramic crowns retained on these different post & core systems. Twenty-one extracted maxillary central human incisors were selected for this study from patient with average age between 25-35 years. All selected teeth were approximately of the same shape, size and root length of 15 mm. (±lmm) from cemento enamel junction The anatomical crowns of all teeth were reduced perpendicular to the long axis of the root using cutting-off disc under copious water coolant leaving a flat surface. The remaining tooth length was standardized at 16 mm. Endodontic procedure was performed to achieve an apical seal. The remaining coronal portion was prepared creating 1mm shoulder finish line with rounded axiogingival line angle circumferentially at the level of CEJ leaving 2 mm of intact tooth structure above the finish line.