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    Effect of fiber reinforcement on color stability of composite resins
    (Wolters Kluwer Medknow Publications, 2020) Karataş, Özcan; Ilday, Nurcan; Bayindir, Funda; Celik, Neslihan; Seven, Nilgun
    Aim: The aim of this in vitro study was to determine the effect of fiber reinforcement on the color changes of two different composite resins. Materials and Methods: A silorane-based composite (Filtek Silorane, A2 shade) and a methacrylate-based composite (Valux Plus, A2 shade) were used in this study. Three groups of samples (control group with no reinforcements, polyethylene fiber [Ribbond THM]-reinforced composite, and glass fiber [everStick®Net]-reinforced composite groups) were prepared from each composite (n = 8). The color change was calculated between baseline and 1 day (DE1) and between baseline, 7 days (DE2), and 21 days (DE3) with a spectrophotometer. The data were analyzed by ANOVA, Duncan's multiple-range tests and independent sample t-test. Results: Statistical analysis of variance presented the statistically significance difference between composite, fiber, and time for DE (P < 0.05). The Ribbond reinforced composite showed a similar color change to the control group (?E = 3.69), while the everStick reinforced composite showed the largest total color change (?E = 4.13). It was determined that the time is an effective factor on the color stability of reinforced composites (P < 0.05). Conclusion: The addition of fiber may lead to color change in composite resins. The amount of change may differ depending on the structural properties of the composite resin or the fiber and time. © 2020 Wolters Kluwer Medknow Publications. All rights reserved.
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    Effect of staining and bleaching on the microhardness, surface roughness and color of different composite resins
    (Wroclaw Medical Univ, 2021) Karataş, Özcan; Gul, Pinar; Akgul, Nilgun; Celik, Neslihan; Gundogdu, Mustafa; Duymus, Zeynep Yesil; Seven, Nilgun
    Background. There are studies that examined the effect of staining on the surface properties of composite resins, using different solutions and bleaching applications. However, the effect of both staining and bleaching on the same composite specimens is an issue that needs to be investigated. Objectives. The aim of this study was to investigate the surface microhardness, roughness and color changes (Delta E) of 2 different composite resins after staining and bleaching. Material and methods. A microhybrid and a nanohybrid composite were used in the study. One hundred and fifty specimens were prepared from each composite. The specimens were divided into 5 groups and stained for 30 days with tea, coffee, cola, red wine, or distilled water (control). Subsequently, each group was divided into 3 subgroups. Each subgroup received a 14-day application of Opalescence (TM) Boost, Opalescence PF or VivaStyle (R) Paint On Plus bleaching materials. The color as well as surface microhardness and roughness of all specimens were determined at baseline, after staining and after bleaching. Data was analyzed using the repeated-measures analysis of variance (ANOVA) and the Bonferroni method. Results. A statistically significant decrease was observed in the surface microhardness of the microhybrid composite specimens after bleaching (p < 0.05).The highest Delta E values were observed in the red wine groups for both composite resins. Conclusions. Staining and bleaching may affect surface properties and color, depending on the type, filler and matrix content of the composite resin.