الفهرس | Only 14 pages are availabe for public view |
Abstract direction then fired in Programat P300 furnace Ivoclar Vivadent (IV), Schaan, FL. While for Subgp P specimens were polished with a sequence of three diamond burs ; coarse, medium and fine (K0262 Dialite ZR intra-oral adjustment finishing and polishing system. Brasseler (Br) USA) followed by applying diamond polishing paste (Zi- polish, bredent, GmbH & Co.KG (br)) with application brush (Wheel Brush Rodeo. (br)) which is double loaded with natural horse hair. Each step was done for 60 seconds with a total of 4 mins. per sample. Finally for Subgp PG polished with the same sequence of the polishing kit without use of diamond paste and then the glaze was applied by the same described manner. Accelerated aging in a steam autoclave (M 11 ultraclave autoclave. Midmark USA. (MD)) for 8 consecutive cycles in 134°C 2 bar pressure. Measurements for color reproduction of shade A2 (Δ E) were done using (VITA Easyshade Compact (VT)) spectrophotometer while for translucent parameter TP and opalascent parameter OP a laboratory spectrophotometer with integrating sphere (Cary 5000 UV- vis-NIR Agilent Technologies (AT) Inc., Santa Clara, CA,USA ) was used. The results of color reproduction with VITA Easyshade Compact (VT) were: GP I showed significantly lower Δ E than GP II regardless of surface finish and aging process. Subgp P showed lowest ΔE values followed by Subgp G with no statistical significance, and the significantly highest ΔE values were for Subgp PG in all conditions. Aging had no effect on color reproduction. Results of translucency and opalescence as measured with Cary 5000 UVvis- NIR (AT) showed that: coloring technique had no effect on translucency nor opalescence. Aging, regardless coloring technique and surface finishing procedure, decreased (TP) values led to a less translucent material and increased (OP) values significantly. For surface finish inverse relation between their effect on TP and on OP values as; while Subgp P showed the highest TP value regardless of other variables, it showed the lowest OP values. The exact opposite was with Subgp G where the lowest TP values and highest OP values were reported. Subgp PG was in between in all tested conditions. |