Diş Hekimliği Fakültesi / Faculty of Dentistry

Permanent URI for this collectionhttps://hdl.handle.net/11727/2120

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2014 - 20162

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Author: search.filters.author.Acar, OzlemSubject: search.filters.subject.IN-VITRO

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    Effect of Different Surface-Cleaning Techniques on The Bond Strength of Composite Resin Restorations
    (2014) Erkut, Selim; Yilmaz, Burak; Bagis, Bora; Kucukemen, Cigdem; Ozdemir, Erdem; Acar, Ozlem; 24939254
    Statement of problem. Different techniques have been suggested for cleaning dentin surfaces after the removal of an interim prosthesis and before the application of a bonding agent. How different surface-cleaning techniques affect the bond strength of the composite resin restorations is not clear. Purpose. The purpose of this study was to investigate the effects of different surface-cleaning techniques on the bond strength of composite resin restorations and the surface topography of the prepared tooth surfaces. Material and methods. The occlusal surfaces of 25 molars were ground until the dentin was exposed. A bonding agent and interim cement were applied on the teeth. The teeth were divided into 5 groups (n=5) according to the method used for surface-cleaning (microairborne-particle abrasion, alcohol, rubber-rotary instrument, desiccating agent, and control). Once the surfaces of the teeth had been cleaned, the same bonding material was applied to the teeth. A 5-mm-thick composite resin layer was built up. Each specimen was sectioned to microbars, and 6 centrally located beams were selected for microtensile testing (n=30) (1.10 +/- 0.10 mm). The data were statistically analyzed with 1-way ANOVA (1-sample Kolmogorov-Smirnov test). The Bonferroni test was used for significantly different groups (alpha=.05). One specimen from each group was observed under a scanning electron microscope and an atomic force microscope. Energy dispersive x-ray analysis also was performed. Results. Bond strength values were in the following descending order: microairborne-particle abrasion, desiccating agent, alcohol, rubber-rotary instrument, control. Differences between the microairborne-particle abrasion group and the remainder of the groups, desiccating agent-rubber-rotary instrument, desiccating agent-control, alcohol-rubber-rotary instrument, and alcohol-control groups, were statistically significant (P<.05). The microairborne-particle abrasion group displayed the roughest surface and a different surface topography from the remainder of the groups. Increased aluminum was observed in the microairborne-particle abrasion group. Conclusions. Surface-cleaning techniques, except for the rubber-rotary instrument, increased the bond strength of composite resin. The roughest dentin surfaces and highest bond strength were achieved with the microairborne-particle abrasion technique.
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    Color Stainability of CAD/CAM and Nanocomposite Resin Materials
    (2016) Acar, Ozlem; Yilmaz, Burak; Altintas, Subutay Han; Chandrasekaran, Indumathi; Johnston, William M.; 26386483
    Statement of problem. The color stainability of recently introduced computer-assisted design/computer-assisted manufacturing (CAD/CAM) hybrid ceramic and resin nanoceramic is unknown. Purpose. The purpose of this in vitro study was to compare the effect of coffee staining on the color of 3 different CAD/CAM restorative materials and a nanocomposite resin. Material and methods. Specimens from a hybrid dental ceramic (VITA Enamic), a resin nanoceramic (Lava Ultimate), a lithium disilicate glass ceramic (IPS e.max CAD), and a nanocomposite resin (Filtek Supreme Ultra Universal) were evaluated for color change due to thermocycling in coffee (n=5). Specimens 0.5 to 0.7 mm and 1 to 1.2 mm in thickness were thermocycled for 5000 cycles. CIEDE2000 color differences (Delta E-00) due to thermocycling in coffee were calculated using the color coordinates obtained from a spectroradiometer. ANCOVA was used to analyze the color differences among the materials with thickness as the covariate. Significant differences at average thickness were analyzed with the Tukey-Kramer test. Results. For color difference due to staining, thickness was a significant covariate (P<.001). Regarding the analysis of color differences, every pair of the tested materials was significantly different (P<.001). Least squares means of color differences (Delta E-00) at mean thickness were 4.34 for the nanohybrid composite resin, 3.66 for the resin nanoceramic, 1.35 for the hybrid ceramic, and 0.43 for the lithium disilicate ceramic. Conclusion. When exposed to hot and cold coffee, the color change was beyond clinical acceptability for the tested resin nanoceramic and nanocomposite resin materials. The average color change of the hybrid ceramic was clinically perceivable over the tested thickness values. The color change of lithium disilicate ceramic was not clinically perceivable at any tested thickness.