Andreas Koenig

Andreas Koenig
University of Leipzig · Department of Dental Prosthetics and Materials Science

Priv.-Doz. Dr. rer. nat. habil., Dipl.-Ing.
https://www.uniklinikum-leipzig.de/einrichtungen/zahn-prothetik/werkstoffkunde/über-uns

About

92
Publications
18,159
Reads
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376
Citations
Additional affiliations
June 2018 - March 2020
University Leipzig
Position
  • Laboratory Manager
Description
  • More informations at: https://www.uniklinikum-leipzig.de/einrichtungen/zahn-prothetik/unser-team
Education
March 2013 - May 2018
Institute of Mineralogy, Crystallography and Materials Science
Field of study
  • Alkali Activated Binder, Geopolymer, Micro X-ray tomography (µXCT)
June 2009 - February 2013
Institute of Mineralogy, Crystallography and Materials Science
Field of study
  • Acid Resistance, Concrete, Biogas Plants
September 2005 - May 2009
Leipzig Institute for Materials Research and Testing (MFPA Leipzig)
Field of study
  • High Performance Concretes

Publications

Publications (92)
Article
Objectives: When consumed in excess, acidic foods and beverages can cause dental erosions leading to irreversible loss of tooth substance. In many cases, prosthetic rehabilitation of the damaged teeth is mandatory. The aim of this in vitro study was to investigate, for the first time on this scale, the resistance of various commonly used self-adhes...
Article
Full-text available
In the study the influence of different dental technical tools on the surface temperature and phase composition of fixed dental prostheses (FDPs) made of yttria-partially stabilized zirconia polycrystals (3Y-/4Y-/5Y-PSZ) was investigated. FDPs were fabricated by using computer-aided manufacturing (CAM). The FDPs were treated with a contra-angle han...
Article
Full-text available
Acid resistance of CAD/CAM resin composites. Erosion-related tooth surface loss is closely related to acid exposure, such as contact with acidic beverages or disease-related reflux. As a result, dental restorations in affected patients are also exposed to acids, which indicates that the performance and longevity of a dental restoration is impacted...
Article
Full-text available
Eight late medieval to early modern red beads representative of a total of 41 from a cesspit of the “Fronerei auf dem Schrangen” in Lübeck, Germany, were investigated using micro X-ray computed tomography (3D-μXCT), X-ray microdiffraction (μ-XRD2), transmission electron microscopy (HRTEM) and Raman spectroscopy (RS). The microscopic properties of t...
Article
This study evaluated the pull-off force between titanium abutments and zirconia crowns that were bonded using four different cements and two abutment heights (AHs). In total, 24 titanium abutments (3-mm AH: n = 12; 5-mm AH: n = 12; taper: 7.5 degrees) and 24 zirconia crowns were designed, manufactured, cemented with one of four dental cements (one...
Article
Objective: The aim of this study was to compare the fracture behavior of cantilever fixed dental prostheses (FDPs) fabricated from 3Y-TZP, 4Y-TZP, or 5Y-TZP zirconia. Method and materials: Posterior cantilever FDPs (three groups, each n = 16) were digitally designed and milled. After sintering, eight specimens/group were stored in demineralized...
Article
Full-text available
New resin-based composites and resin-infiltrated ceramics are used to fabricate computer-aided design (CAD) and computer-aided manufacturing (CAM)-based restorations, although little information is available on the long-term performance of these materials. The aim of this investigation was to determine the effects of storage time (24 h, 90 days, 18...
Article
Acidification of implant microenvironment and inflammation due to degradation products of high molecular weight poly(α-hydroxy acids) like PLA and PLGA is a risk that can limit their use in regenerative medicine, tissue engineering and drug delivery. We developed macromers that consist of a three-armed core with varying degrees of ethoxylation, hyd...
Article
The aim of this in vitro study was to analyse the performance of CAD/CAM resin-based composites for the fabrication of long-term temporary fixed dental prostheses (FDP) and to compare it to other commercially available alternative materials regarding its long-term stability. Four CAD/CAM materials [Structur CAD (SC), VITA CAD-Temp (CT), Grandio dis...
Article
Full-text available
Background: The influence of typical manufacturing regimes for producing fixed dental prostheses (FDPs) from yttria partly-stabilized zirconia polycrystals (3Y/4Y/5Y-TZP) on the phase composition is quantified. Methods: Fixed dental prostheses (FDPs) were designed using a CAD process and machined from different Y-TZP blanks from two manufacturer...
Chapter
This work reports the results of an extensive experimental campaign aimed at investigating the Thermal Energy Storage (TES) behavior of PCM Recycled Brick Aggregate (RBA) mortars. Test specimens for TES measurements were produced following a new spherical-shaped technique, patented as “DKK test” by the Institute of Construction and Building Materia...
Article
Full-text available
The effect of dental technical tools on the phase composition and roughness of 3/4/5 yttria-stabilized tetragonal zirconia polycrystalline (3y-/4y-/5y-TZP) for application in prosthetic dentistry was investigated. Additionally, the X-ray diffraction methods of Garvie-Nicholson and Rietveld were compared in a dental restoration context. Seven plates...
Article
Full-text available
The performance of dental resin-based composites (RBCs) heavily depends on the characteristic properties of the individual filler fraction. As specific information regarding the properties of the filler fraction is often missing, the current study aims to characterize the filler fractions of several contemporary computer-aided design/computer-aided...
Article
Full-text available
The aim of the study was to investigate the effect of X-rays used in micro X-ray computer tomography (µXCT) on the mechanical performance and microstructure of a variety of dental materials. Standardised bending beams (2 × 2 × 25 mm3) were forwarded to irradiation with an industrial tomograph. Using three-dimensional datasets, the porosity of the m...
Article
Full-text available
The performance of artificial nerve guidance conduits (NGC) in peripheral nerve regeneration can be improved by providing structures with multiple small channels instead of a single wide lumen. 3D-printing is a strategy to access such multi-channeled structures in a defined and reproducible way. This study explores extrusion-based 3D-printing of tw...
Article
Dank der kontinuierlichen Weiterentwicklung im Bereich der zahnärztlichen Materialien stehen uns heute verschiedenste zahnfarbene Werkstoffe zur Verfügung, die dem Wunsch nach ästhetischen und biokompatiblen festsitzenden zahnärztlichen Versorgungen in besonderem Maße gerecht werden. Mit dem vorliegenden Artikel sollen die verschiedenen, sich gegen...
Article
Full-text available
In this study, we integrated different calcium sources into sol-gel hybrid glass scaffolds with the aim of producing implants with long-lasting calcium release while maintaining mechanical strength of the implant. Calcium(II)-release was used to introduce bioactivity to the material and eventually support implant integration into a bone tissue defe...
Article
Objectives: An abnormal development of teeth can result in malformed teeth. Indirect resin composites that can be fabricated with the computer-aided design/computer-aided manufacturing (CAD/ CAM) technique are available for the fabrication of permanent restorations. This case report presents the esthetical and functional rehabilitation of a 10-year...
Article
Los composites indirectos pueden procesarse mediante tecnología CAD/CAM como materiales de color dental para restauraciones definitivas. Consisten en duroplasto, cuerpos de relleno inorgánicos, silano y aditivos. Se polimerizan industrialmente a gran presión y bajo temperaturas elevadas. Se comercializan tanto en forma de discos como de bloques, qu...
Data
A section of an orthodontric bracket was photographed using macro photography (Olympus OM-D EM1 II, lens tube adapter, NIKON CF Plan 20x) with focus variation. Three different plot profiles were created using the resulting depth map. Validation of the data was performed with conventional focus-stacking microscopy (VK-X1000, KEYENCE) and a subsequen...
Data
A high-resolution image of each bracket was created using focus stacking (upper row). Based on the resulting depth map, the surface could be created by a suitable 3D visualization (middle row). Using a conventional microscope, the same areas were analyzed by focus stacking for optical comparison.
Article
Objectives: The goal of this study was to show the potential of the inexpensive macro photography technique for application in various fields of contemporary dental materials science. The method was used for studying surface characteristics for fractographic evaluation, topography analysis, and for the measurement of optical properties such as tra...
Article
Full-text available
Objectives The aim of this study was to analyse the impact of different clinical conditioning approaches and an ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based experimental primer for intraoral luting of buccal tubes on silica-based ceramic surfaces. Materials and methods A total of 60 leucite-reinforced glass ceramic molar cro...
Article
Air void parameters in cementitious materials are usually identified and analysed manually using image techniques such as incident light microscopy (ILM). The investigative procedure requires considerable effort, and the analysis results can vary between operators. This article presents an approach to the analysis of air void parameters (air void d...
Article
Full-text available
This paper investigates the development of the alkalinity and its impact on carbon steel reinforcement embedded in alkali-activated fly ashes (AAFA) and alkali-activated fly ashes with ten percentage mass (wt%) of blast furnace slag (AAFAS)-based materials (geopolymer-GP). The pH analysis of eluates indicates a remarkable decrease of alkalinity in...
Conference Paper
This work reports the results of an extensive experimental campaign aimed at investigating the Thermal Energy Storage (TES) behavior of PCM Recycled Brick Aggregate (RBA) mortars. Test specimens for TES measurements were produced following a new spherical-shaped technique, patented as "DKK test" by the Institute of Construction and Building Materia...
Article
A new discrimination method for the bioapatite materials bone, antler and ivory was developed using X-ray diffractometry and comprises non-invasive measurements in order to take valuable objects into account. Our approach deals with the analysis of peak intensity ratios resulting from several measurements on each object. For instance, the intensity...
Article
Full-text available
Objectives Modern dentistry is increasingly focusing on digital procedures, including CAD/CAM technologies. New materials have to resist in a demanding environment that includes secondary caries occurrence. The current study hypothesized that the microbiological behavior of different RBCs for CAD/CAM applications is better than that of their counte...
Article
Full-text available
This paper reports a numerical approach for modelling the thermal behavior and heat accumulation/liberation of sustainable cementitious composites made with Recycled Brick Aggregates (RBAs) employed as carriers for Phase-Change Materials (PCMs). In the framework of the further development of the fixed grid modelling method, classically employed for...
Article
Indirekte Komposite lassen sich als zahnfarbene, definitive Restaurationsmaterialien mittels CAD/CAM verarbeiten. Sie bestehen aus Duroplasten, anorganischen Füllkörpern, Silan sowie Additiven und werden industriell bei großem Druck und hohenTemperaturen polymerisiert. Erhältlich sind sie sowohl in Ronden- als auch in Blockform und in verschiedenen...
Conference Paper
Full-text available
The use of concrete as construction and building material has enormously increased in the last decades. Innovations in the concrete industry are asking for answers in terms of reusing construction demolishing waste, energy saving concepts and cost-effective solutions for CO2 reductions. Therefore, the concrete industry has committed itself towards...
Article
This paper provides preliminary results of a research study on the fatigue behavior of Ultra-High-Performance Concrete (UHPC). Results of an experimental campaign, performed at the Department of Concrete Structures and Structural Engineering of the TU-Kaiserslautern, are firstly proposed. The heterogeneous meso-structure and material degradation of...
Article
The aim of the current study was to relate an artificial aging protocol for the analysis of dental materials to their clinical performance. 20 fixed interim restorations (crowns and fixed denture prostheses (FDPs)) fabricated from two commercially available resin-based composites (RBCs) and a previous clinical trial served as templates for the fabr...
Article
A slight decrease of the compressive strength and a higher porosity could be observed with fibers. Only StF in Geopolymer-and PPF in AAS-concretes increased the flexural tensile strength. StF reinforced OPC-and AAFA-concretes showed a post-softening behavior. Imperfections on the fiber surface were visualized by mXCT. A post-hardening behavior was...
Article
A dealuminated Y-zeolite with a n Si /n Al ratio of 130 is treated in pure water and aqueous solutions of NaCl at different pH values between 3 and 7 at 100 °C for up to 3 weeks. The change of specific micropore volume, the specific external surface, and the mesopore size distribution are monitored by N 2 -adsorption (77 K). The decrease of micropo...
Conference Paper
Full-text available
ie Mikro-Röntgen-Computertomographie (µ-XCT) eignet sich im Bereich der zementgebundenen Werkstoffe zur ortsaufgelösten Analyse von einzelnen, sich hinsichtlich ihrer Dichte vom restlichen Gefüge unterscheidenden Bestandteilen wie z.B. Poren, Fasern und Risse. Die zerstörungsfreie Wirkungsweise ermöglicht darüber hinaus Mehrfachmessungen identische...
Article
The aim of this work is to study the effect of phase composition and microstructure of cordierite-based co-clinkers on the electrical properties and coefficient of thermal expansion of cordierite briquettes. To achieve this aim talc and kaolinite samples were collected from quarries in the Egyptian desert. The samples are characterized using XRD, X...
Conference Paper
In the large Late Iron Age and Early Roman Iron Age urnfields of the Lower Elbe region, there are often objects found outside the urn. Especially with those examples where the objects were deposited in the immediate vicinity of the vessel, it is apparently beyond doubt that they represented grave goods. The question is if this also applies to objec...
Article
Full-text available
Background In joint revision surgery, bone cement extraction remains a major challenge which even today has not seen a satisfactory solution yet. We studied in an experimental setting the impact of heat sources on the mechanical properties and microstructure of bone cement and determined the glass transition temperature (TG) of bone cement. As a re...
Article
Full-text available
The interest in concretes based on alkali-activated binders (AABs) is increasing significantly along with the continued research into and development of these novel construction materials from lab scale to practical application. The paper summarizes current knowledge about concretes based on AABs to address the following questions: What are structu...
Article
This paper summarizes the results of investigations into the material resistance of mortars and concretes based on alkali-activated binders (AABs) under organic acid attack (acetic, propionic, lactic acid with pH ≈ 3). The development of the residual strength, degradation depth and mass loss over time were recorded after six, twelve and 18 weeks of...
Conference Paper
Full-text available
Der durch organische Säuren verursachte Schädigungsgrad in Mörteln sowie Betonen korreliert mit dem Ca-Anteil des eingesetzten Bindemittels. Der Austausch von Portlandzement durch Flugasche hatte eine Absenkung des Portlandit-Anteils und eine reduzierte Schädigungstiefe sowie einen geringeren Festigkeitsverlust zur Folge. Mit alkalisch-aktiviertem...
Conference Paper
Alkalisch-aktivierte Bindemittel und Geopolymer-Bindemittel rücken immer mehr in den Fokus der Betonindustrie. Der Beitrag liefert eine allgemeine Zusammenfassung der aktuell verfügbaren Literatur sowie der eigenen Erfahrungen und adressiert dabei folgende Fragestellungen: Was sind alkalisch-aktivierte Bindemittel und Geopolymer-Bindemittel? Wie un...
Conference Paper
Full-text available
Bauwerke des Hoch-, Industrie- und Ingenieurbaus sind während ihrer Nutzungsdauer verschiedenen Belastungsbedingungen ausgesetzt. Neben den dauerhaften bzw. häufig wiederkehrenden Einwirkungen kann es auch zu außergewöhnlichen Beanspruchungen kommen, wozu beispielsweise auch der Brandfall zählt. Das Verhalten von Beton im Brandfall ist prinzipiell...
Article
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A coral bead chain from the Hanseatic City Greifswald (Mecklenburg-Vorpommern, Germa-ny) from around 1300 was archaeometrically examined by non-destructive or minimally invasive methods. Thereby, this artefact was established as a genuine red coral from the Medi¬terranean Sea, and therefore corresponding trade routes towards central Europe can be s...
Article
Full-text available
Concretes in biogas plants (BGP) are subjected to chemical damage through acids which are formed by microbiological processes. Four-year-old grass silage clamp and different concretes samples were analysed. The tests allow statements on the plant-specific damage potential and the performance of the concretes used. Acetic and lactic acids were produ...
Article
Full-text available
The aim of this work is to optimize the industrial applications of granite and kaolinite rock tailings in ceramics industry. Three rock tailings are selected to be characterized and equally mixed for testing. The samples are characterized using XRD, XRF, polarizing light microscope, cathodoluminescence, X-ray micro-computed tomography (3d-µCT) and...
Conference Paper
Full-text available
The use of ternary cements, is one of the strategies investigated to improve sustainability in construction. However, in construction sites, concrete and mortars with ternary cements and high dosages of admixtures show a high variability in rheological properties, especially with temperature changes. Supplementary materials have an effect in the hy...
Poster
Full-text available
Due to the transition of linear to stroked ornamented ware from Eythra (near Leipzig, central Germany), we studied sherds asking if those ornamental signatures are correlated with provenance and firing technology. The results are based on chemical analyses by XRF, texture and pores by computer tomography and optical microscopy as well as by phase a...
Article
Full-text available
Nicht nur unter technischen, sondern zunehmend unter Aspekten der Wirtschaftlichkeit und Nachhaltigkeit wird die Erforschung von alternativen Bindemitteln und Zementersatzstoffen mit ausgeprägten reaktiven Eigenschaften verstärkt vorangetrieben. Hierbei spielen neben bereits seit längerem bekannte Betonzusatzstoffe wie z.B. Flugasche, Silikastaub u...
Article
The aim of this work is to track neogenic minerals and microstructures in degraded aluminosilicate refractories. Six samples are used to represent the low, moderate and high alumina bricks and low-cement castables as working linings. In addition, a steelmaking converter slag is used as the attacking agent/medium. The samples are characterized using...
Conference Paper
Full-text available
Based on the knowledge of the deterioration mechanisms of different acid solutions the performance of UHPC – amongst others – in different acid environments was comparatively tested. The interconnection between the acid solutions and UHPC was examined by pH-value measurements, light microscopy (LM), scanning electron microscopy with energy dispersi...
Poster
Full-text available
Conclusion • Young‘s modulus of AAFA is low compared to cementitious binders with similar compressive strength and decreases over time (decrease in density probably leads to increase porosity). • Stress strain behavior of AAFA is dominated by linear behavior up to fracture, resulting in rapid failure. • For the provision of generalised design recom...
Article
Full-text available
Research into alternative binders and cement substitutes with distinctively reactive properties is being pursued not only from a technical but increasingly also from an economic and sustai