EFFECT OF REPRESSING AND GLAZING ON COLOR REPRODUCTION, TRANSLUCENCY AND SURFACE ROUGHNESS OF LITHIUM DISILICATE GLASS-CERAMICS
El-Etreby, Amr S.
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Statement of problem: During heat-pressing of lithium dislilicate glass-ceramics, It is more economical to press several restorations from one ingot at the same time. However, this is often not possible and may result in a considerable amount of leftover material (The sprues and button). It has been reported that the leftover materials after heat-pressing are reused (repressed) in some dental laboratories. Sufficient knowledge about the consequences of such procedure is not available. The issue is thereby raised whether the leftover material should be discarded or reused. Materials and Methods: Twenty IPS e.max press discs (Pressed and Repressed groups n=10) of 15mm diameter, 1 mm thickness, in shade A3 were fabricated using heat pressed technique. Only the button parts and not the sprues were used for repressing. Color reproduction and translucency were measured using the Vita Easyshade spectrophotometer. Surface roughness was measured using a 3D laser scanning microscope. Crystalline structure and microstructural features present in pressed, and repressed material were described using Xray diffraction, EDAX and scanning electron microscope.
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