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    Effect of different sintering conditions on microstructural characterisation of Co-Cr metal laser powder
    (Inderscience Publishers, 2020) Pekkan, Gürel; Taşçı, Eda; Pekkan, Keriman; Ispalarlı, Murat
    Co-Cr alloys have been used for many years in dentistry. In recent years, the fabrication of prosthetic restorations from Co-Cr alloys by metal laser sintering method has become widespread. This method is a combination of powder metallurgy and three-dimensional printing technologies. The surface microstructure of the material and the different phases formed on the surface of the material after sintering and heat treatment are extremely important since these metal substructures are layered with dental porcelain in fixed prosthetic dentistry. In this study, characterisation of Co-Cr alloy samples produced by direct metal laser sintering (DMLS) method and sintering under various atmospheric conditions were performed with X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray diffractometer (EDX). It was observed that sintering with different methods under various atmospheric conditions affected the XRD phase intensities. The sintering in the argon gas atmosphere yielded a more significant phase separation that facilitates the identification of different phases in XRD patterns. Copyright © 2020 Inderscience Enterprises Ltd.
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    Effect of sintering regimes and thickness on optical properties of zirconia ceramics for dental applications
    (Blackwell Publishing Ltd, 2021) Pekkan, Keriman
    In dentistry, monolithic zirconia restorations have been preferred over all-ceramic restorations in recent years. Translucency is an aesthetic demand in dental restorations, and it can be identified with translucency parameter (TP). Zirconia thickness, Y2O3 content, and sintering conditions are important parameters that influence the translucency of the restorations. It is crucial to investigate monolithic zirconia ceramics under different sintering regimes and reveal the critical parameters for dental restorations. The aim of this study was to determine the optical and microstructural behaviors of monolithic zirconia ceramics containing different amounts of yttria depending on various sintering regimes and thicknesses. Therefore, a conventional zirconia CopranZri (CZI) and two monolithic zirconia materials, CopraSupreme (CSP), CopraSmile (CSM) were used. Slow, normal, speed, and translucency sintering regimes with thicknesses of 0.7, 1.0, 1.3 mm were selected. TP of the specimens was calculated, and statistical analyses were performed by using one-way ANOVA and Tukey-Kramer post hoc tests. Characterization of the specimens was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) techniques. The results showed that the effect of different sintering programs is more critical for CSP and CSM in terms of translucency variations and translucency program led to the most grain growth. © 2021 The American Ceramic Society
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    Factors affecting the translucency of monolithic zirconia ceramics: A review from materials science perspective
    (Japanese Society for Dental Materials and Devices, 2020) Pekkan, Gürel; Pekkan, Keriman; Çukurluöz Bayındır, Banu; Özcan, Mutlu; Karasu, Bekir
    The use of monolithic [yttria (Y2O3)-stabilized tetragonal zirconia (ZrO2) polycrystalline] (Y-TZP) ceramics to restore teeth is expanding in dentistry. However, there are still some problems about color matching and the translucency of these ceramics. The employment of Y-TZP ceramics in aesthetically critical regions is questionable due to the insufficient translucency and opacity of the restorations. The objective of this review was to assess the factors affecting the translucency of monolithic Y-TZP ceramics for a better understanding the relevant parameters in restorations. The translucency of polycrystalline ceramics is a complex phenomenon. Apprehending the translucency regarding ceramics requires their knowledge of physical, chemical and microstructural characteristics with the light interactions among them. © 2020, Japanese Society for Dental Materials and Devices. All rights reserved.