PURPOSE To determine the effect of the cement type and abutment material on the tensile strength required to dislodge zirconia copings. MATERIALS AND METHODS Two experimental groups of abutments were prepared: (1) titanium abutments (n = 30) and (2) zirconia abutments (n = 30). Sixty zirconia copings (custom designed) were fabricated using 3-dimensional computer-assisted design to have a 6-mm projection above the abutment to accommodate a hole, through which a wire was inserted to attach the zirconia coping to a universal testing machine. Each abutment was placed onto an implant analog embedded in acrylic resin blocks to fit onto the universal testing machine. The zirconia copings were cemented onto the abutments with a provisional luting agent, zinc phosphate (ZP) cement, and adhesive resin cement, and after 5500 thermocycles, a tensile force was applied at a crosshead speed of 0.5 mm/min. The removal force was recorded for each specimen. Two-way analysis of variance (ANOVA) and 1-way ANOVA were used for the statistical analysis (P < 0.05). RESULTS The mean forces necessary to remove the zirconia copings from titanium abutments were 6.52, 83.09, and 251.18 N for temporary cement, ZP cement, and resin cement, respectively. For zirconia abutments, the required forces were 17.82, 116.41, and 248.72 N. CONCLUSIONS The abutment material had no effect on retention, but the cement type affected the retention of the zirconia copings.

Objective:The aim of this study was 2-fold. The first aim was to evaluate the effects of mixing technique (hand-mixing or auto-mixing) on bacterial attachment to polyether impression materials. The second aim was to determine whether bacterial attachment to these materials was affected by length of exposure to disinfection solutions.Materials and Methods:Polyether impression material samples (n = 144) were prepared by hand-mixing or auto-mixing. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were used in testing. After incubation, the bacterial colonies were counted and then disinfectant solution was applied. The effect of disinfection solution was evaluated just after the polymerization of impression material and 30 min after polymerization. Differences in adherence of bacteria to the samples prepared by hand-mixing and to those prepared by auto-mixing were assessed by Kruskal-Wallis and Mann-Whitney U-tests. For evaluating the efficiency of the disinfectant, Kruskal-Wallis multiple comparisons test was used.Results:E. coli counts were higher in hand-mixed materials (P < 0.05); no other statistically significant differences were found between hand- and auto-mixed materials. According to the Kruskal-Wallis test, significant differences were found between the disinfection procedures (Z > 2.394).Conclusion:The methods used for mixing polyether impression material did not affect bacterial attachment to impression surfaces. In contrast, the disinfection procedure greatly affects decontamination of the impression surface.

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Eight coordination polymers (CPs), namely, [Co(m-phsuc)(m-obix)]n (1), {[Co2(m-phsuc)2(m-pbix)1.5]×2H2O}n (2), [Zn(m-phsuc)(m-obix)]n (3), {[Zn(m-phsuc)(m-mbix)]×H2O}n (4), {[Zn(m-phsuc)(m-pbix)]×H2O}n (5), {[Zn(m-phsuc)(m-pbix)]×1.5H2O×CH3OH}n (6), [Cd(m-phsuc)(m-obix)]n (7) and [Cd(m3-phsuc)(m-pbix)0.5]n (8) (phsucH2 = 2-phenylsuccinic acid, obix = 1,2-bis((imidazol-1-yl)methyl)benzene, mbix = 1,3-bis((imidazol-1-yl)methyl)benzene, pbix = 1,4-bis((imidazol-1-yl)methyl)benzene), were solvothermally synthesized and characterized by IR spectroscopy, elemental analysis, X-ray single-crystal diffraction, X-ray powder diffraction (PXRD), and thermal analyses. The structural analyses revealed that the compounds were 2D coordination polymers, in which metal ions were in tetrahedral coordination geometries in 1-6 and in octahedral coordination geometries in 2, 7 and 8. Compounds 1, 3, 4, 5, 7 and 8 displayed a 4-connected 2D wave sheets with the point symbol of {44.62}. Compound 2 was rare example exhibiting a 2D polyrotaxane structure. Compound 6 showed a 2D two-fold interpenetrating 3-connected hcb net with the point symbol of {63}. In the compounds, the neighboring 2D layers were further assembled by p×××p stacking and weak C–H×××p interactions into the 3D supramolecular framework. The effects of the bis(imidazole) linkers and metals ions on the framework assemblies have been discussed. In addition, thermal and photoluminescent properties of the compounds were investigated.

Son yüzyılda, teknolojik gelişmelere paralel olarak sanayileşmedeki hızlı artış, iş kazalarına da yansımaktadır. İş sağlığı ve güvenliği, insanlığın çalışma gereksinimi duymaya başlamasından beri kavramsal olarak karşımıza çıkmaktadır. İlkel toplumlardan günümüze iş bölümü yapılmakta ve yapılan işlerde standartlaşma ve çeşitlilik, işçi sağlığı ve güvenliğini zorunlu duruma getirmektedir. Peyzaj mimarlığı uygulama alanlarında yürütülen her proje birbirinden farklı iş gücü, teknik ve mekânlar içermekte ve bu farklılıklara bağlı olarak çalışanlar açısından farklı risk ve tehlikeler meydana getirmektedir. Bu çalışmada peyzaj mimarlığı alanında iş sağlığı ve güvenliği ile ilgili tanımları ortaya koyarak mevzuat ve uygulamaya yönelik gelişim aşamalarının Türkiye'de nasıl ilerlediği irdelenmektir. Bu amaçla peyzaj mimarlığı uygulama alanlarında şantiye personelinin iş sağlığı ve güvenliği konusuna bakışı ele alınmaktadır. Personelin kendi sorumluluklarını içeren mevzuatları ne kadar takip ettikleri ve ne kadar uygulamaya aktarabildikleri sorgulanmaktadır. Ayrıca, alan çalışmalarında iş sağlığı ve güvenliğinin uygulanabilirliği yönüyle dikkat edilmesi gereken konular irdelenmektedir. Bu kapsamda Ankara İlinde seçilen şantiye alanında gözlem yapılarak personel ve yöneticilerle görüşülmüştür. Peyzaj uygulama hizmetlerinde görev yapan personelin konuyla ilgili görüşleri alınarak kendi sorumluluklarını içeren mevzuatları ne kadar takip ettikleri ve ne kadar hayata geçirdikleri sorgulanmıştır. Peyzaj uygulama hizmetlerinde iş sağlığı ve güvenliğinin uygulanabilirliği yönünden dikkat edilmesi gerekenler bakımından çözüm önerileri geliştirilmiş ve çalışma sonucunda ortaya çıkan bilgiler ışığında geleceğe yönelik önerilerde bulunulmuştur.

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