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

This study was conducted to evaluate the effect of relative thickness of different resin composite systems using enamel and dentin shades following the natural layering concept on the final color outcome. Ninety resin composite discs were assigned according to resin composite system into three groups of 30 discs each: Ceram X Duo (S1), filtek{u2122} Z350 XT (S2) and amaris® (S3). Each group was divided in to 3 subgroups (n = 10) according to the relative enamel (E): Dentin (D) thickness in to 0.5mm E: 1.5mm D (T1), 1 E: 1 D (T2), 1.5 E:0.5 D (T3) on top of 0.5mm thick basic enamel background as a standardized layer simulating the clinical condition. A vitapan A2 classical shade tab was used as a reference shade to which the different specimens of the three tested systems were compared. Color parameters (L*, a*, b*) and color difference ({u2206}E) were measured and calculated using an electronic shade detection device which is VITA Easyshade® Advance 4.0 over a black background. UV- shimadzu 3101 pc-spectrophotometer was also used in this study to confirm the results obtained by easyshade advance 4.0. The results were analyzed by analysis of variance (ANOVA)/Tukey's post hoc test (p < 0.05) for L*, b* and {u2206}E, while Kruskal{u2013}Wallis test followed by paired group comparisons using mann whitney U tests for a*. As the thickness of the enamel shade increased, the L* value decreased and the a* and b* values of the tested materials tended to shift towards the green and blue in the red-green axis and yellow-blue axis respectively. All tested composite systems at all thickness

Issued also as CD