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    3D micro-CT analysis of void formations and push-out bonding strength of resin cements used for fiber post cementation
    (Korean Acad Prosthodontics, 2016) Uzun, Ismail Hakki; Malkoc, Meral Arslan; Keles, Ali; Ogreten, Ayse Tuba
    PURPOSE. To investigate the void parameters within the resin cements used for fiber post cementation by micro-CT (mu CT) and regional push-out bonding strength. MATERIALS AND METHODS. Twenty-one, single and round shaped roots were enlarged with a low-speed drill following by endodontic treatment. The roots were divided into three groups (n=7) and fiber posts were cemented with Maxcem Elite, Multilink N and Superbond C&B resin cements. Specimens were scanned using mu CT scanner at resolution of 13.7 mu m. The number, area, and volume of voids between dentin and post were evaluated. A method of analysis based on the post segmentation was used, and coronal, middle and apical thirds considered separately. After the mu CT analysis, roots were embedded in epoxy resin and sectioned into 2 mm thick slices (63 sections in total). Push-out testing was performed with universal testing device at 0.5 mm/min cross-head speed. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (alpha=.05). RESULTS. Overall, significant differences between the resin cements and the post level were observed in the void number, area, and volume (P<.05). Super-Bond C&B showed the most void formation (44.86 +/- 22.71). Multilink N showed the least void surface (3.51 +/- 2.24 mm(2)) and volume (0.01 +/- 0.01 mm(3)). Regional push-out bond strength of the cements was not different (P>.05). CONCLUSION. mu CT proved to be a powerful non-destructive 3D analysis tool for visualizing the void parameters. Multilink N had the lowest void parameters. When efficiency of all cements was evaluated, direct relationship between the post region and push out bonding strength was not observed.
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    The effect of repair protocols on shear bond strength to zirconia and veneering porcelain
    (Taylor & Francis Ltd, 2016) Uzun, Ismail Hakki; Malkoc, Meral Arslan; Polat, Nilufer Tulin; Ogreten, Ayse Tuba
    The aim of this study was to evaluate the shear bond strength (SBS) of a new repairing material including zirconia primer to zirconia and veneering porcelain after various surface treatments. A total of 60 specimens (30 zirconia-Zr and 30 feldspathic porcelain-Feld) were prepared and divided into 6 groups (n=10). Two surface preparations (air abrasion-AA and Erbium Yag (Er-YAG) Laser-Las) were applied to the specimens. Zr and Feld specimens treated with a grinding bur according to manufacturer advice, were used as control (C). Repair material (Cimara Zircon, VOCO, Germany) was applied to the specimens 2mm in height. The SBS was measured in a universal testing machine at 1mm/min crosshead speed. The SBS data (MPa) were analyzed using two-way ANOVA and Tukey HSD multiple comparison tests (=0.05). Significant effects of the material type (p=0.005) and the surface treatment strategy (p=0.000) were found. Interaction terms were also significant (p=0.000). While the Zr-C (68,4MPa) showed the highest SBS (p<0.05), Zr-Las (16,4MPa) had the lowest SBS (p<0.05). The highest SBS value was obtained when both zirconia and veneering porcelain were treated with a grinding bur without any additional surface treatment.