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    Cytotoxicity evaluation of removable partial denture alloys were obtained from different laboratories
    (Cumhuriyet University Faculty of Dentistry, 2011) Sahin, Onur; Dogan, Derya Özdemir; Polat, Zübeyde Akin
    Objectives: The aim of this study was assess cytotoxicty of removable partial denture alloys which were obtained from different laboratories. Methods: 1 mm diameter, 1.5 mm thickness disc-shaped metal specimens which were applied sandblasting and sandblasting+polising process were obtained from four different laboratories activing in Sivas. Specimens were performed in sterile with ethylene oxide gas and then placed on to the L929 fibroblast cell culture. According to the 2009 ISO 10993-5 protochols, cytotoxicity were determined by means of agar overley test. Results: According to the lysis of the cells, specimens which were obtained from four laboratories, three of them were not cytotoxic while one of them was slightly cytotoxic. Moreover all groups in our study which applied sandblasting and sandblasting + polising process, were no significant difference in cytotoxicty. Conclusions: Laboratories use recasted metal alloys not only for economic reasons but also because of nesicence. The importance is emerging that technicians must be informed about the relationship between recasting process and biological risk and also size of the biological risk.
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    The effects of therapeutic x-ray doses on mechanical, chemical and physical properties of poly methyl methacrylate
    (INFORMA HEALTHCARE, 2013) Dogan, Derya Ozdemir; Ozguven, Yildiray; Karakus, Gulderen; Sahin, Onur; Polat, Nilufer Tulin; Yucel, Birsen; Dogan, Mansur
    Aim. The aim of this study was to investigate the effect of radiation doses very close to the human dose for oral cancers on mechanical, chemical and physical properties for poly methyl-methacrylate (PMMA). Methods. PMMA samples were divided into four different groups: no irradiated group, 25-Gy irradiated group, 50-Gy irradiated group and 75-Gy irradiated group. Each group contained nine samples. After 24 h, a three-point loading test was applied to each PMMA groups. The transverse strength and the elastic modulus were calculated using the test results. The results were analyzed statistically by using one-way analysis of variance. The structural characterizations of the PMMA samples were carried out by a Fourier Transform Infrared (FTIR) spectrophotometer to evaluate the chemical structure differences. Results. The transverse strength values of 25-Gy, 50-Gy and 75-Gy radiation groups were significantly higher than that of the no radiation group (p < 0.05). There was no significant difference among the elastic modulus values of the study groups (p > 0.05). The FTIR findings demonstrated that the irradiation process did not change the chemical structure of the PMMA polymeric materials. Conclusion. The therapeutic radiation doses increase the mechanical properties of the PMMA; however, the chemical and structural properties have no effect. When the findings of this study are taken into account, it can be said that patients can wear dentures during the radiotherapy.
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    Investigation of flexural strength and cytotoxicity of acrylic resin copolymers by using different polymerization methods
    (KOREAN ACAD PROSTHODONTICS, 2015) Sahin, Onur; Ozdemir, Ali Kemal; Turgut, Mehmet; Boztug, Ali; Sumer, Zeynep
    PURPOSE. The aim of this study was to appraise the some mechanical properties of polymethyl methacrylate based denture base resin polymerized by copolymerization mechanism, and to investigate the cytotoxic effect of these copolymer resins. MATERIALS AND METHODS. 2-hydroxyethyl methacrylate (HEMA) and isobutyl methacrylate (IBMA) were added to monomers of conventional heat polymerized and injection-molded poly methyl methacrylate (PMMA) resin contents of 2%, 3%, and 5% by volume and polymerization was carried out. Three-point bending test was performed to detect flexural strength and the elasticity modulus of the resins. To determine the statistical differences between the study groups, the Kruskall-Wallis test was performed. Then pairwise comparisons were performed between significant groups by Mann-Whitney U test. Agar-overlay test was performed to determine cytotoxic effect of copolymer resins. Chemical analysis was determined by FTIR spectrum. RESULTS. Synthesis of the copolymer was approved by FTIR spectroscopy. Within the conventional heat-polymerized group maximum transverse strength had been seen in the HEMA 2% concentration; however, when the concentration ratio increased, the strength decreased. In the injection-molded group, maximum transverse strength had been seen in the IBMA 2% concentration; also as the concentration ratio increased, the strength decreased. Only IBMA showed no cytotoxic effect at low concentrations when both two polymerization methods applied while HEMA showed cytotoxic effect in the injection-molded resins. CONCLUSION. Within the limitations of this study, it may be concluded that IBMA and HEMA may be used in low concentration and at high temperature to obtain non-cytotoxic and durable copolymer structure.
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    ONN donor half-salen ligands and their dioxomolybdenum(VI) complexes: Synthesis, crystal structure, experimental-theoretical characterizations and molecular docking studies
    (Elsevier, 2025) Portakal, Eylem Dilmen; Kaya, Savas; Berisha, Avni; Kaya, Yeliz; Sahin, Onur; Ercag, Ayse
    The half-salen ligand (L1) synthesized from 3,4-diaminobenzophenone with 2-hydroxy-1-naphthaldehyde and the new half-salen ligand (L2) synthesized from 4-(diethylamino)salicylaldehyde were used in the preparation of dioxomolybdenum(VI) complexes (C1 and C2). The characterization of the synthesized compounds was carried out by elemental analysis, IR, 1H NMR, UV-Vis and conductivity measurements. The molecular structure of the C2 complex was elucidated by X-ray crystallography. Spectroscopic data show that the half-salen ligands behave as dibasic tridentate ligands and coordinate via phenolic oxygen, azomethine nitrogen and primary amine nitrogen. Both the primary amine group and the hydroxyl group bonded to the molybdenyl center by losing one proton. The complexes, [MoO 2 (L1-L2)(Solv)], are nonelectrolyte and octahedral in structure. The sixth coordination is completed by a solvent molecule (C1: water and C2: ethanol). In addition, the chemical reactivities of the ligands and complexes were analyzed and compared with each other via reactivity descriptors and electronic structure principles of Conceptual Density Functional Theory (CDFT). The interactions with EGFR Kinase domain complexed with tak-285 (PDB ID: 3POZ of L1, L2, C1 and C2 were checked via Molecular Docking analysis. In the light of the relations found between CDFT descriptors and docking scores, it was noted that the most reactive chemical system C1 which has with lowest chemical and highest electrophilicity index interacts more powerful with selected protein.