Browsing by Author "Koc, Serap Gungor"

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Investigation of Surface Structure and Biocompatibility of Chitosan-Coated Zirconia and Alumina Dental Abutments
(Wiley, 2018) Kalyoncuoglu, Ulku Tugba; Yilmaz, Bengi; Koc, Serap Gungor; Evis, Zafer; Arpaci, Pembegul Uyar; Kansu, Gulay
Background: For long-term success of dental implants, it is essential to maintain the health of the surrounding soft tissue barrier, which protects the bone-implant interface from the microorganisms. Although implants based on titanium and its alloys still dominate the dental implant market, alumina (Al2O3) and zirconia (ZrO2) implant systems are widely used in the area. However, they provide smooth and bioinert surfaces in the transmucosal region, which poorly integrate with the surrounding tissues. Objective: The main aim of this research was to investigate the surface characteristics and biocompatibility of chitosan-coated alumina and zirconia surfaces. Materials and Methods: The substrates were coated via solution casting technique. Additionally, an aging process with a thermocycle apparatus was applied on the coated materials to mimic the oral environment. To define the morphology and chemical composition of the surfaces of untreated, chitosan-coated, and chitosan-coated-aged samples, scanning electron microscopy and energy dispersive X-ray spectrometry were used. The phases and bonds characterized by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The human gingival fibroblast cells were used to evaluate cytocompatibility by a 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium salt assay. Results: It was observed that both substrates were successfully coated with chitosan and the aging process did not significantly affect the integrity of the coating. The attachment and proliferation of human gingival fibroblast cells were shown to be good on both kinds of chitosan-coated surfaces. Conclusion: Coating zirconia and alumina surfaces with chitosan is an efficient surface modification for increasing biocompatibility and bioactivity of these materials in vitro.
Synthesis and Characterization of Strontium and Chlorine Co-Doped Tricalcium Phosphate
(Elsevier, 2019) Koc, Serap Gungor
The strontium (Sr2+) and chlorine (Cl-) substituted tricalcium phosphate (TCP) were synthesized via aqueous precipitation method. To understand the effect of the Sr2+ and Cl- doping on mechanical properties of tricalcium phosphate (TCP) ceramics, dense TCP compacts of different compositions were prepared and sintered at 1100 degrees C for 1 h. X-ray diffraction of sintered samples revealed that dopants turn into beta-TCP to HA phase transformation during sintering. The binary combination and amount of co-dopants significantly affect the microstructure. The microhardness of the samples increased with increasing of the Sr2+ and Cl- ion concentrations. Cl- ion addition, 2.5-10 mol% affect micro hardness results negatively. A comparison between samples were carried out and differences were considered statistically significant at p < 0.05 (standard deviation: 1.2296 GPa). (C) 2019 Elsevier B.V. All rights reserved.
Synthesis of Biphasic Calcium Phosphate (Bcp) Coatings on Β-Type Titanium Alloys Reinforced With Rutile-Tio2 Compounds: Adhesion Resistance and In-Vitro Corrosion
(Springer, 2018) Dikici, Burak; Niinomi, Mitsuo; Topuz, Mehmet; Koc, Serap Gungor; Nakai, Masaaki
In this study, beta( )type Ti-29Nb-13Ta-4.6Zr alloys coated with biphasic calcium phosphate (BCP) reinforced with rutile-TiO2 compounds by sol-gel technique to evaluate its possible usage in biomaterial science. Calcium nitrate tetrahydrate (Ca(NO3)(2)center dot 4H(2)O), di-ammonium hydrogen phosphate (NH4)(2)HPO4), ammonium hydroxide (NH4OH), and titanium (IV) propoxide (Ti(OC3H7)(4)) (Merck, Germany) were used as precursors for producing the BCP-only and BCP/TiO2 composite coatings. Synthesis and coating procedure, surface morphology, adhesion strength, and corrosion results of the coated samples have been investigated in details. XRD technique has been used in order to characterization of BCP phases. The morphological observations of coatings were determined by using a scanning electron microscopy (SEM). In-vitro corrosion behaviors of the coatings have been determined with polarization method in Ringer's electrolyte at body temperature. It was found that the BCP/TiO2 coating synthesized on TNTZ alloy has higher scratch resistance than BCP-only coating due to its containing rutile-TiO2 compounds. In addition, it can be said that the BCP/TiO2 coated sample was less susceptibility to corrosion than the BCP-only coatings and uncoated TNTZ sample in simulated body fluid. [GRAPHICS] .