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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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    Bond Strength of Resin Cement to Yttrium-Stabilized Tetragonal Zirconia Ceramic Treated with Air Abrasion, Silica Coating, and Laser Irradiation
    (Mary Ann Liebert, Inc, 2010) Akyil, Musa Samil; Uzun, Ismail Hakki; Bayindir, Funda
    Objective:The purpose of this study was to evaluate the shear bond strength of a resin cement to yttrium-stabilized tetragonal zirconia (Y-TZP) surfaces treated with air abrasion, silica coating, or CO2, Er:YAG, or Nd:YAG laser irradiation, or irradiated by each laser after air abrasion. Background Data:Optimized methods are needed to improve the adhesive bonding between resin cement and Y-TZP ceramic. Methods:Twelve specimens were irradiated with each laser at different parameters and examined by scanning electron microscopy to determine which parameters to use in this study. One hundred forty-one Y-TZP discs were assigned to nine groups:C, no treatment; AA, air abrasion; CJ, silica coating; ER, Er:YAG laser; ND, Nd:YAG laser; CO, CO2 laser; AA+ER, air abrasion+Er:YAG laser; AA+ND, air abrasion+Nd:YAG laser; AA+CO, air abrasion+CO2 laser. The composite cylinders were fabricated. After the surface treatments, the specimens were silanized and composite cylinders were cemented with the resin cement. The shear bond strength test was performed after specimens were stored in water for 24 h and after thermocycling for 500 cycles. Results:The highest bond strength was obtained in the AA group and was similar to that of the CJ group. In C, ER, CO, ND, AA+ND, and AA+CO groups, the shear bond strengths were similar to each other according to the Duncan test results. The lowest bond value was obtained in the AA+ER group. Conclusion:Although air abrasion and silica coating were the most effective surface treatment methods, CO2 and Er:YAG laser irradiation alone or Nd:YAG laser irradiation after air abrasion may be used as an alternative treatment method to increase the bond strength between resin cement and Y-TZP material.
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    Effect of impression valve system on adhesion force of impression materials to edentulous maxillary jaw: a preliminary clinical study
    (Taylor & Francis Ltd, 2015) Akpinar, Yusuf Ziya; Uzun, Ismail Hakki; Yilmaz, Betul; Tatar, Numan
    Objective: The purpose of this preliminary clinical study was to evaluate the effect of novel impression valve system (IVS) on adhesion force of different impression materials to edentulous maxilla. Background data: Impression materials and techniques have an important role in complete denture success. During the functional impression with an individual impression tray (IIT), high adhesive forces exist between edentulous ridge and impression material. Removing the IIT from the mouth with minimal force provides the most accurate and non-deformed impression. Materials and methods: This study included twenty maxillary edentulous patients (n = 20). Patients who had palatal torus, anatomic undercut, gagging reflex, and flabby ridges were excluded from the study. The age range of the participants was 55-70. All patients gave written informed consent. Two impression materials - zinc oxide eugenol (ZOE) and alginate - were used as experimental material. The digital dynamometer was used to determine the adhesion force of impression materials with and without IVS to edentulous maxilla. The mean values of the adhesion forces were analyzed using the Wilcoxon signed-ranks test (alpha = 0.05). Results: The effect of IVS on adhesion force was found to be statistically significant (p<0.05). There were also statistical differences between the ZOE and alginate groups (p<0.05). Conclusions: The IVS is useful to remove the functional impression from the mouth without any deformation and detaching in cases which high adhesive force occurs.
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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.
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    Evaluation on Shear Bond Strength of Different Glass Ionomer and Hydroxy Apatite Cements Used in Ossiculoplasty
    (AVES,, 2015-01) Kalcioglu, M. Tayyar; Uzun, Ismail Hakki; Yalcin, Muhammet; Malkoc, Meral Arslan; Öğreten, Ayse Tuba; Hanege, Fatih Mehmet
    Background: Glass ionomer cements (GIC) have been widely used in dentistry for many years. In recent years, GIC have also been used for ossiculoplasty. The bond strength of GIC used in ossiculoplasty and the way they may change over the years in the cementation area are being questioned. The bonding strength of the substance may be of importance for long-term outcomes. Aims: The aim of this study was to investigate the bond strength of different GIC on ossicles. Study Design: In vitro study. Methods: Twenty ossicles were obtained from patients who had undergone ear surgery. All specimens were randomly divided into four subgroups. All specimens were inserted into a specially designed apparatus for shear bond strength (SBS) testing. The tested materials [Aqua Meron (AM), Aqua Cem (AC), Ketac Cem (KC), and Otomimix CPB (OH)] were prepared and applied according to the manufacturer's instructions. The SBS was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Results: The mean SBSs were found to be 13.28 MPa, 23.43 MPa, 8.51MPa, and 1.78 MPa for AM, AC, KC, and OH, respectively. AC had the highest SBS, which was statistically significantly different from that of KC and OH (p<0.05). Both AM and KC had higher SBS than OH (p<0.05). Conclusion: The results obtained in this study by investigating the bone-bonding strength of cements widely used in ossiculoplasty demonstrate that some of these substances have a greater ability to bond to ossicles compared to others. Further clinical investigations are needed to test different parameters.
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    In vitro evaluation of long-term cytotoxic response of injection-molded polyamide and polymethyle metacrylate denture base materials on primary fibroblast cell culture
    (Informa Healthcare, 2013) Uzun, Ismail Hakki; Tatar, Abdulgani; Hacimuftuoglu, Ahmet; Saruhan, Fatih; Bayindir, Funda
    Objective. This study investigated the long-term cytotoxic response of thermoplastic polyamide and conventional polymethyle metacrylate (PMMA) denture base materials. Materials and ethods. Twenty discs were prepared for each polyamide, heat and cold cured PMMA denture base resins (totally 60) and divided into four sub-groups (n = 5). Cytotoxicity was assessed with the direct cell contact method using cell viability and neutral red (NR) uptake assay. Each sub-group was tested at initial and after being aged for 24 h, 1 week and 8 weeks with artificial saliva according to ISO 10993 standards. Results. There were no significantly difference among the materials and control groups after initial, 24 h and 1 week testing. In 24 h testing, only Deflex was more toxic according to the Control group (p < 0.05). After 8 weeks of aging with artificial saliva, all materials were significantly cytotoxic when compared to the control group. QC20 was more toxic than Deflex and SC Cold Cure (p < 0.05). There were significant differences between the 8 week aging group and the initial, 24 h and 1 week testing for all materials (p < 0.05). Conclusions. Cytotoxicity of all tested denture base materials increased significantly after the long-term aging. Therefore, long-term aging may be useful to determine a dental material's toxicity. Polyamide denture base material had a similar toxicity profile with conventional heat-and cold-cured PMMA.