Yazar "Evis, Zafer" seçeneğine göre listele
Listeleniyor 1 - 6 / 6
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Çeşitli İyonlar Eklenmiş NanoHidroksiapatitler: Üretim Yöntemleri, İç Yapı, Mekanik ve Biyouyumluluk Özellikleri Yönlerinden İncelenmesi(Kırıkkale Üniversitesi, 2011) Evis, ZaferDue to the resemblance of grain sizes of nano hydroxyapatite to that of apatite minerals in bone, the researches on nano hydroxyapatite have become to gain great importance. In this study, general information were presented about the synthesis methods, biocompatibility, microstructural and mechanical characteristics of nano-crystalline hydroxyapatite. The characteristics of hydroxyapatite doped with various ions were generally examined, how and which ions contributed to hydroxyapatite was studied.Öğe Effect of storage time on mechanical properties of extended-pour irreversible hydrocolloid impression materials(MOSBY-ELSEVIER, 2020) Sahin, Volkan; Jodati, Hossein; Evis, ZaferStatement of problem. Recent commercial extended-pour irreversible hydrocolloid impression materials (EPIHIMs) claim to maintain dimensional stability up to 120 hours. However, data regarding their mechanical properties and performance after 120 hours of storage are lacking. Purpose. The purpose of this in vitro study was to test the elastic recovery, strain in compression, and tear strength properties of 5 commercially available EPIHIMs, immediately after preparation and after 120 hours of storage under specific storage conditions. Material and methods. A total of 150 specimens were prepared in accordance with the ISO 21563:2013 standard from 5 commercially available EPIHIMs (Blueprint Xcreme, Kromopan, Alginmax, Hydrogum 5, and Alginelle). The specimens were subjected to elastic recovery, strain in compression, and tear strength tests immediately after specimen preparation (n=5) and after 120 hours of storage inside clear plastic zipper bags held at 23 degrees C (n=5). Data were analyzed with a multivariate analysis of variance (MANOVA) test for brand and duration parameters. Normality of data was analyzed with the Shapiro-Wilk test. The Duncan test or Games-Howell test was used for multiple comparisons (alpha=.05). Results. Elastic recovery and strain in compression values of the EPIHIMs tested were affected by brand and duration parameters (P<.001). Tear strength values of the EPIHIMs tested were affected by brand (P<.001); however, they were not affected by duration (P>.05). Data distribution was normal except for Alginmax in terms of the elastic recovery values and Blueprint Xcreme in terms of the strain in compression values (P<.05). Significant interactions were present between brand and duration for the strain in compression and tear strength values of the EPIHIMs tested (P<.05). Statistically significant difference was not found among mean elastic recovery values of the tested EPIHIM brands (P<.001). Moreover, a statistically significant increase was present in elastic recovery values of the tested EPIHIMs after 120 hours of storage (P<.001). Statistically significant difference was not found among mean strain in compression values of the tested EPIHIM brands tested immediately after preparation (P>.05). However, 120 hours of storage led both to a statistically significant decrease in mean strain in compression values of the tested EPIHIMs (P<.001) except for Alginelle (P>.05) and a statistically significant difference among mean strain in compression values of the tested EPIHIM brands (P<.001). Storage time did not influence mean tear strength values of the EPIHIMs tested (P>.05). However, statistically significant differences were present among mean tear strength values of the tested EPIHIM brands tested immediately after preparation (P<.001) and after 120 hours of storage (P<.001). Conclusions. Despite variations in elastic recovery, strain in compression, and tear strength properties of the EPIHIMs tested, all the materials fulfilled the requirements to comply with the ISO 21563:2013 standard even after 120 hours of storage.Öğe Effect of Storage Time on Tear Strength of Extended-Pour Irreversible Hydrocolloid Impression Materials(2018) Şahin, Volkan; Jodati, Hossein; Evis, ZaferObjective: The aim of this in vitro study was to evaluatethe effect of prolonged storage times on the tear strength ofextended-pour irreversible hydrocolloid impression materials.Material-Method: Eighty four specimens were fabricatedfrom five commercial extended-pour irreversiblehydrocolloid impression materials (BluePrint Xcreme,Hydrogum 5, Kromopan, Alginmax and Alginelle) as wellas one experimental formula in accordance with the ISO21563:2013 standard effective for irreversible hydrocolloidimpression materials. Specimens were randomly divided intwo groups for each impression material (n=7) and subjectedto tear strength test immediately (base line) or after 120 hoursof storage. Tear strength values were obtained in N/mm anddata were analysed with two-way ANOVA (irreversiblehydrocolloid brand, storage time). Multiple comparisonswere performed with Tukey’s test (p=0.05).Results: The tear strength of the extended-pour irreversiblehydrocolloid impression materials were affected by brand(p<0.0001) and brand-storage time interaction (p=0.005).Storage time did not influence the tear strengths of theextended-pour irreversible hydrocolloid impression materialstested except Alginmax whose mean tear strengths increasedafter 120 hours of storage (p<0.05). At base line measurementsBlueprint Xcreme provided the highest mean tear strengthvalues (1.08±0.19 N/mm) whereas Alginelle provided thelowest mean tear strength values (0.51±0.3 N/mm). Hydrogum5 provided the highest tear strength values after 120 hours ofstorage (1.15± 0.12 N/mm) whereas Alginelle provided thelowest mean tear strength values (0.55±0.04 N/mm).Conclusions: All commercial extended-pour irreversiblehydrocolloid impression materials tested maintained their tearstrengths after 120 hours of storage.Öğe Effects of the doping concentration of boron on physicochemical, mechanical, and biological properties of hydroxyapatite(Elsevier Sci Ltd, 2022) Jodati, Hossein; Tezcaner, Aysen; Alshemary, Ammar Z.; Sahin, Volkan; Evis, ZaferIon doping is an approach to modify properties of materials, like hydroxyapatite (HA), that contributes to designing biomaterials with desired characteristics applicable in bone defect treatments. Recently, boron (B) has been noticed in biomaterial fields due to its beneficial effects on formation, growth, and quality of bone. In this study, B-doped HA nanoparticles with different molar concentrations of B (0.05, 0.1, 0.25, and 0.5) were synthesized through microwave-assisted wet precipitation. The effects of B content on various properties of HA were evaluated. The results demonstrated that the size of HA particles reduced from 106 nm to 89-85 nm in B doped materials. Meanwhile, the crystallinity degree of B doped HA (BHA) samples was between 89.90% and 93.77%, compared to 95.19% of HA. Diametral tensile strength of samples was measured in the ranges of 2.51 and 3.61 with no significant difference among groups. The micro-hardness of HA was 0.88 GPa, whilst doped ones had hardness values of 0.5 GPa-0.68 GPa. Biodegradability of samples increased from less than 1% to approximately 4% after 28 days, while B-doping did not make any change in the degradation rate. Doping dosages were appropriate in terms of bioactivity and cell viability, and B doping caused higher bioactivity and cell proliferation. All changed properties were dose-dependent and more effective in doped groups with a higher amount of B. Despite proliferative effect, <= 260 mu g/l and 770 mu g/l of B release in two groups with the highest dopant concentrations did not positively influence the osteogenic activity of cells. Our results demonstrated that doping concentrations that resulted in B release & LE;260 mu g/l seem more appropriate dosage, especially for bone tissue engineering and substitute applications due to promoted bioactivity and proliferation, as well as no obstructive effects on mechanical properties and osteogenic activities of HA.Öğe Silver and fluoride doped hydroxyapatites: Investigation by microstructure, mechanical and antibacterial properties(Elsevier Sci Ltd, 2013) Turkoz, Mustafa; Atilla, Aykan Onur; Evis, ZaferHydroxyapatite co-doped with Ag+ and F- ions was synthesized by the precipitation method and sintered at 1100 degrees C for 1 h. Samples were characterized by density, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy to investigate their microstructure, phase formation and bonding characteristics. Moreover, samples were also characterized by microhardness and antibacterial tests. Small amount of dopings resulted in high densities and fine grain microstructures. In most of the samples, hydroxyapatite was the main phase with a minor amount of beta-TCP. Presence of fluoride and small amount of TCP was verified with all characteristic FTIR bands of hydroxyapatite for most of the samples. Compared to the pure hydroxyapatites, much higher microhardness values were measured in samples co-doped with Ag+ and F- ions. Antibacterial activity of the materials related to Escherichia coli was also observed in hydroxyapatite samples with high amount of Ag+ ions. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Öğe Zirkonya İlave Edilmiş Hidroksiapatitlerin Yoğunluk ve İç Yapı İncelemeleri(Kırıkkale Üniversitesi, 2010) Evis, ZaferZirkonya ilave edilmiş hidroksiapatitler çöktürme yöntemi ile üretilmiş ve 1100ºC ve 1300ºC’lerde 1 saat havada sinterlenmişlerdir. Zirkonya ilave edilmiş hidroksiapatitlerde 3- kalsiyum fosfat gibi ikincil fazlar oluşmuştur. Ayrıca, zirkonya eklenmiş hidroksiapatitlerin kafes parametrelerindeki farklılıkların sebebi, hegzagonal kristal yapısına ilave edilmiş olan bazı Zr4+ iyonlarıdır. Saf hidroksiapatitin teorik yoğunluğuna ulaşması için sinterleme sıcaklığı olarak 1100 ºC yeterli olurken, zirkonya ilave edilmiş hidroksiapatitlerde, yoğun malzeme üretimi için 1100 ºC’den yüksek sinterleme sıcaklıkları gerektiği belirlenmiştir.
