Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Dental Materials

The study was performed to evaluate the color change of amine free dual cured resin cement (NX3) versus amine containing one; (Variolink) in three storage media (in air, distilled water and coffee) and time intervals (one week, two weeks and six weeks). Moreover, the degree of conversion and water sorption of both cements were also assessed. A total number of fifty eight discs of resin cement specimens were used. The specimens were divided into two main groups according to the type of resin cement used: Group 1 (control):amine containing Variolink II dual cure cement (n=29/gp), Group2: amine free NX3 dual cure cement (n=29/gp).In each group, three main tests were performed: I) Evaluation of color change (n=15), the specimens in each group were subdivided into three subgroups according to storage media: air, distilled water and coffee (n=5/subgp), II) Evaluation of degree of conversion (n=7/gp), each specimen was assessed at four time intervals: immediately after light curing, one hour, 24 hours and two weeks, III) Evaluation of water sorption (n=7/gp). For color change test, each specimen was evaluated using a spectrophotometer at three time intervals: a) After one week, b) After two weeks, c) After six weeks. In both air and distilled water Variolink II showed significantly higher mean color change value than NX3 after one and two weeks.This might be attributed to the chemical composition of Variolink II which contains tertiary amines as chemical activator for the polymerization reaction. However, within the coffee subgroup Variolink II showed the higher significant mean color change value than NX3 after one and six weeks{u2019} time interval but there was no significant difference between them after two weeks.This might be caused by presence of melanoidins in coffee which are water soluble

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