الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
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’ 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.