الفهرس 
Efficacy of at home bleaching on color stability of hybrid ceramic restorations
CONTENTSOnly 14 pages are availabe for public view
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Abstract
This study was designed to assess the efficacy of at home bleaching (10% and 20% carbamide peroxide OPF) with two frequencies of application at 2 months interval on color stability and surface roughness of hybrid ceramic restorations. A total of 40 vita Enamic discs were be sectioned under water irrigation applications with a precision cutting machine IsoMet 1000 into discs with dimensions 2mm thickness and 11 mm diameter as measured by digital caliper. The Vita Enamic hybrid ceramic samples were polished with Vita Enamic polishing set by simple pre- and high-gloss polishing of VITA ENAMIC hybrid ceramic kit according to manufacturing instructions. All samples (40 discs) will be divided into to three main test groups group (A): 8 Samples is the control group. group (B): 16 samples are bleached with carbamide peroxide 10%-opalescence PF. And group (C): 16 samples bleached with carbamide peroxide 20%-opalescence PF. Groups B and care further classified into two subgroups according to times of exposure for bleaching agent for each, subgroup I: After first exposure to bleaching agent and subgroup II: After second exposure to bleaching agent. The bleaching agent was applied 8 hours per day for 14 days for first exposure while group A samples were immersed in artificial saliva for 14 days, after 14 days samples of group A and subgroups I of the two groups (B and C) were prepared for color change and surface roughness measurements, while subgroups II for each group (B and C) were immersed in artificial saliva for 2 months, after that these samples were exposed for bleaching agent for another 14 days and prepared for color change and surface roughness measurements