Diş Hekimliği Fakültesi / Faculty of Dentistry

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

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2016 - 20172

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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.
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    Effect of Fabrication Stages and Cementation on The Marginal Fit of CAD-CAM Monolithic Zirconia Crowns
    (2017) Kale, Ediz; Yilmaz, Burak; Seker, Emre; Ozcelik, Tuncer Burak; 28434679
    Statement of problem. Monolithic zirconia crowns fabricated using computer-aided design and computer-aided manufacturing (CAD-CAM) technology have recently become an alternative dental prosthetic treatment. The marginal fit of monolithic zirconia crown may be affected by different stages of the fabrication procedures in the laboratory and cementation. Information regarding the accuracy of fit of monolithic zirconia crowns at different stages of fabrication and cementation is limited. Purpose. The purpose of this in vitro study was to evaluate the effect of different stages of fabrication and cementation on the vertical marginal discrepancy (VMD) of CAD-CAM fabricated monolithic zirconia crowns. Material and methods. Six ivorine right maxillary first molar typodont teeth with standardized anatomic preparations for complete coverage ceramic crowns were scanned with a 3-dimensional laboratory scanner. Crowns were designed using CAD software and milled from presintered monolithic zirconia blocks in a 5-axis dental milling machine. A cement space of 25 pm for the margins and a 50-gm space starting 1 mm above the finish lines of the teeth were virtually set in the CAD software. A total of 144 measurements were performed on 6 specimens with 8 measurement locations in 3 different stages using stereoscopic zoom microscopy; after initial production of the crowns (post-sintering group), after glazing (post-glazing group), and after cementation (post-cementation group). The VMD values were statistically analyzed with 1-way repeated measures ANOVA and the Holm-Sidak method (alpha=.05). Results. Different stages of fabrication and cementation significantly affected the VMD of tested crowns (P=.003). The mean VMD was 38 gm for post-sintering group, 38 pm for post-glazing group, and 60 mu m for post-cementation group, with statistical differences between the post-sintering group, the post-cementation group (P<.002), and the post-glazing group and post-cementation group (P<.003); there were no statistical differences between the post-sintering group and the post-glazing group (P=.966). Conclusions. Within the limitations of this in vitro study, glazing did not significantly change the VMD of CAD-CAM monolithic zirconia crowns. Cementation significantly increased the VMD values.