542
1995
eng
522
74
article
0
--
--
--
The impact of diamond-like coatings on the strength of dental ceramics
Journal of Dental Research
Helga Hornberger
Peter M. Marquis
J. Franks
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
563
2001
eng
5
patent
0
--
--
--
Composite material and method for the preparation thereof
A composite material with a porous inorganic-nonmetallic matrix and a second material, characterized in that said porous inorganic-nonmetallic matrix has a bending strength of >=40 MPa as measured according to ISO 6 872; said second material is an organic material which at least partly fills the pores of said porous matrix; and said composite material has a modulus of elasticity, E, of >=25 GPa as measured according to ISO 10 477.
https://depatisnet.dpma.de/DepatisNet/depatisnet?action=bibdat&docid=US020090001623A1
Stefan Aechtner
Helga Hornberger
Emil Nagel
Norbert Thiel
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
562
2003
eng
8
patent
0
--
--
--
Method of making a ceramic restoration
Production of a dental reconstruction comprises: (a) forming a mold (12) from a model (10); (b) using (12) to make an isotropically heat-expandable replica from a ceramic precursor (14); (c) oxidizing (14) to produce an enlarged ceramic replica; (d) forming a silicone mold from this replica; (e) using (d) to make a second ceramic replica; and (f) sintering the second replica with volume reduction to form a replica identical to (10).
Verfahren zur Herstellung einer Zahnrestauration aus Keramik
https://depatisnet.dpma.de/DepatisNet/depatisnet?action=bibdat&docid=EP000001346702A1
Ulrich Muerrle
Helga Hornberger
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
539
1996
eng
44
49
2
69
article
0
--
--
--
Machining of silica glasses using excimer laser radiation
Glastechnische Berichte - Glass Science and Technology
Helga Hornberger
R. Weissmann
N. Lutz
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
534
2011
eng
1746
1755
29
176
article
0
--
--
--
Effect of fetal calf serum on the corrosion behaviour of magnesium alloys
The corrosion behaviour of WE43 magnesium alloys using the mini cell system was studied. Voltammetry and impedance spectroscopy were applied to study on the one hand the effect of microstructure of the working electrode and on the other hand the effect of proteins in the electrolyte. Two types of alloy samples were produced (i) by permanent mould casting and (ii) by gas atomization followed by extrusion. The results showed that the microstructure was strongly influenced by the production process. The extruded samples showed an improved homogeneity of phase distribution compared with cast samples as it was aimed for. Due to increased homogeneity it was expected to find higher corrosion resistance. However, the electrochemical results are contradictory and suggest an additional phase in the extruded microstructure. Using energy dispersive X-ray spectroscopy (EDX) the secondary magnesium rare earths (RE) phase of extruded samples showed differing composition than of cast samples as well as additional oxide phases. After the samples were electrochemically investigated in cell medium with and without fetal calf serum (FCS), an impact of FCS was detected in voltammetry due to the length of the polarisation curve. As the tip of the mini cell in contact with the working electrode is small, developing gases tend to spread on the working electrode and break the contact of liquid to the counter electrode; which results in disrupting the current flow. This effect was more pronounced when rising the voltage and was found reduced when using electrolytes with FCS. Impedance spectra were slightly deformed by FCS, seen as a kinetic effect but not as a basic differing corrosion reaction. The insight into the effects of FCS was provided by the mini cell system as this system enables to collect entire series of measurements. In contrast of two single measurements, those series reflected the slight difference caused by FCS. The focus of the electrochemical corrosion study was set on the first half hour of immersion.
Materials Science and Engineering B
10.1016/j.mseb.2011.07.018
Helga Hornberger
Frank Witte
Norbert Hort
Wolf-Dieter Müller
eng
uncontrolled
Magnesium
eng
uncontrolled
Corrosion
eng
uncontrolled
Proteins
eng
uncontrolled
Impedance
eng
uncontrolled
Reproducibility
eng
uncontrolled
Polarization
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
564
2002
eng
8
patent
0
--
--
--
Fully ceramic tooth replacement with a frame made of cer-stabilised zircon-oxide
Vollkeramischer Zahnersatz mit einem Gerüst, das aus einem Gerüstmaterial aus einem Cer-stabilisierten Zirkonoxid (Ce-ZrO2) mit einem Anteil von bis zu 25 Gew% Aluminiumoxid (Al2O3) bezogen auf den Anteil an ZrO2 aufgebaut ist und einem Infiltrationsglasanteil im Gerüst von 0-40 Vol% bezogen auf das Volumen des Gerüsts sowie einer auf das Gerüstmaterial abgestimmten Verblendkeramik.Die Erfindung betrifft die Verwendung von cer-stabilisiertem ZrO2 zur Herstellung von Gerüstmaterialien, die als Restauration im Dentalbereich einsetzbar sind.
Vollkeramischer Zahnersatz mit einem Gerüst aus einem cer-stabilisierten Zirkonoxid
https://depatisnet.dpma.de/DepatisNet/depatisnet?action=bibdat&docid=WO002002047616A3
Helga Hornberger
Norbert Thiel
Markus Vollmann
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
536
2002
eng
44
49
1
88
article
0
--
--
--
The effect of multicolored machinable ceramics on the esthetics of all-ceramic crowns
Statement of problems: Computer-aided design/computer-assisted machining systems offer the possibility of fabricating restorations from one machinable ceramic block. Whether multishaded blocks improve esthetic results and are a viable alternative to individually stained ceramics has not been fully determined.
Purpose: The aim of this investigation was to examine the effect of multishaded blocks on the esthetic appearance of all-ceramic CEREC crowns and compare these crowns with single-shade and stained restorations.
Material and methods: Ten subjects were included in this study. For each subject, 6 different crowns were milled with the use of a CEREC machine. One crown was milled from each of the following machinable ceramic materials: CEREC Vitablocs Mark II in classic colors; Vitablocs Mark II in 3D-Master colors; Vitablocs Mark II in either classic or 3D-Master colors, with additional staining; Megadenta Bloxx multishaded; Mark II experimental multilayer; and an experimental multilayer leucite ceramic. Three independent examiners assessed the esthetic appearance of crowns fabricated to match each subject's anterior tooth shade. A scale of 1 to 6 was used to score the shade match and esthetic adaptation of each crown, with 1 representing excellent characteristics and 3.5 serving as the threshold for clinical acceptability. The examiners' scores were averaged, and the mean values were analyzed with the Wilcoxon signed rank test (P<or=.05).
Results: Only individually stained Mark II restorations achieved a mean score below the threshold of 3.5 for all 10 subjects. These restorations were significantly more esthetic (P<or=.05) than restorations fabricated from all other materials except the Mark II experimental multilayer ceramic. The second best results were obtained for crowns made from single-shaded Mark II 3D-Master blocks: 6 out of 10 restorations were scored below 3.5. Two of the layered materials (Mark II experimental and Bloxx) followed with 5 acceptable restorations out of 10.
Conclusion: Within the limitations of this study, the results provide no evidence that multicolored machinable ceramics improve the esthetics of all-ceramic crowns.
Journal of Prosthetic Dentistry
Sven Reich
Helga Hornberger
eng
uncontrolled
Aluminum Silicates
eng
uncontrolled
Ceramics
eng
uncontrolled
Dental Materials
eng
uncontrolled
Surface Properties
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Lebenswissenschaften und Ethik
Labor Biomaterialien
431
2014
eng
11456
11472
15
article
0
--
--
--
The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys
Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE) is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.
International Journal of Molecular Science
10.3390/ijms150711456
peer-reviewed
Wolf-Dieter Müller
Helga Hornberger
eng
uncontrolled
magnesium
eng
uncontrolled
magnesium alloys
eng
uncontrolled
magnesium hydride
eng
uncontrolled
corrosion
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
530
2019
eng
1
5
June
2
article
Elsevier
0
--
--
--
Degradation and bioactivity studies of Mg membranes for dental surgery
Bioresorbable materials are under investigation due to their promising properties for applications as implant material. This study is about the degradation and bioactivity behaviour of magnesium foils, which allegorize dental membranes. The degradation behaviour including pitting corrosion during immersion tests can be precisely observed using micro-computed tomography. Using the bioactivity test according to Kokubo, it is shown that magnesium has strong Ca-phosphate layer formation correlated with high degradation. Therefore, magnesium foils appear to hold a great potential for bone implant application.
Materials Letter X
10.1016/j.mlblux.2019.100007
peer-reviewed
Creative Commons - CC BY-ND - Namensnennung - Keine Bearbeitungen 4.0 International
Helga Hornberger
Birgit Striegl
M. Trahanofsky
F. Kneissl
Matthias Kronseder
eng
uncontrolled
Magnesium
eng
uncontrolled
Dental membrane
eng
uncontrolled
Bioactivity
eng
uncontrolled
Corrosion rate
Chirurgie und verwandte medizinische Fachrichtungen
Fakultät Maschinenbau
Regensburg Center of Biomedical Engineering - RCBE
Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Lebenswissenschaften und Ethik
Labor Biomaterialien
540
1995
eng
188
194
6
68
article
0
--
--
--
Mechanical properties and microstructure of In-Ceram
Glastechnische Berichte - Glass Science and Technology
a ceramic-glass composite for dental crowns
Helga Hornberger
Peter M. Marquis
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
531
2014
eng
100
108
9
37
article
0
--
--
--
Strengthening of dental adhesives via particle reinforcement
The bond between methacrylic polymer adhesives and dental restoratives is not perfect and may fail either in the short or in the long term. This study aims to evaluate the effects of particle incorporation in a self-etch model adhesive on mechanical and physical properties that are relevant during application and service. Filled adhesives containing 5, 10, 15 or 25 wt% glass fillers were compared to their unfilled counterpart in terms of water sorption and solubility; viscosity and dynamic viscosity during polymerization were recorded using rheological measurements and compared to FTIR analysis of the real-time degree of cure. Elastic modulus and ultimate tensile strength measurements were performed in uniaxial tension; the energy to fracture was used to calculate the fracture toughness of the adhesives. Finally, the experimental adhesives were applied on dentin substrate to test the bond strength using the microtensile test. Results showed that the incorporation of 5–10 wt% nanofiller to self-etching dental adhesives is efficient in accelerating the polymerization reaction and increasing the degree of cure without compromising the film viscosity for good wettability or water sorption and solubility. Fillers increased the elastic modulus, tensile strength and fracture toughness to a plateau between 5 and 15 wt% filler concentration, and despite the tendency to form agglomerations, active crack pinning/deflection toughening mechanisms have been observed. The bond strength between resin composite and dentin was also improved when adhesives with up to 10 wt% fillers were used, with no additional improvements with further packing. The use of fillers to reinforce dental adhesives may therefore be of great practical benefit by improving curing and mechanical properties.
Journal of the Mechanical Behavior of Biomedical Materials
10.1016/j.jmbbm.2014.05.007
peer-reviewed
Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG
Renan Belli
Stefan Kreppel
Anselm Petschelt
Helga Hornberger
Aldo R. Boccaccini
Ulrich Lohbauer
eng
uncontrolled
Nanoparticles
eng
uncontrolled
Bond strength
eng
uncontrolled
Elasticity
eng
uncontrolled
Adhesives
eng
uncontrolled
Dentin
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Lebenswissenschaften und Ethik
Labor Biomaterialien
430
2015
eng
51
57
630
article
0
--
--
--
Fatigue and surface structure of titanium after oxygen diffusion hardening
The characterization of oxygen diffusion zone in titanium and the effect of this zone on macroscopic properties are still of high interest for a base to predict and to enhance life time of titanium and titanium alloy components. The aim of this study was to contribute to the understanding of the impact of oxygen on fatigue properties of oxygen diffusion hardened Ti and Ti alloys. Oxygen diffusion hardening implies two process steps, first the oxidation of the surface and secondly the diffusion of oxygen into metal matrix. Due to the one-step treatment used in this study the oxidation step could take place easily avoiding scaling and grain boundary diffusion. In spite of this precaution, the fatigue properties in the present study were found to be decreased after the performed oxygen diffusion hardening. The reason for the reduction of mechanical properties were claimed to be oxide clusters on the surface acting as crack initiation sites. Comparison and discussion with literature revealed varying partially contradictory fatigue results. Therefore precise analysis of the fatigue failure is necessary as a base for further development of the oxygen diffusion hardening.
Materials Science & Engineering A
10.1016/j.msea.2015.02.006
Helga Hornberger
Clemens Randow
Claudia Fleck
eng
uncontrolled
Titanium alloys
eng
uncontrolled
Oxygen diffusion
eng
uncontrolled
Surface hardening
eng
uncontrolled
Fatigue
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
535
2007
eng
1428
1437
11
23
article
0
--
--
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A proposal for the classification of dental alloys according to their resistance to corrosion
Objectives
The purpose of this study was to establish a method to compare and classify dental alloys in relation to their resistance to corrosion.
Methods
Alloy samples and pure metal samples were prepared and tested in chemical and electrochemical corrosion according to ISO 10271. For electrochemical test, the rest potential versus time and a potentiodynamic scan were recorded. After chemical corrosion test, the ions released were analyzed by ICP (induced coupled plasma) spectroscopy.
Results
High gold alloys had a similar polarization curve than gold. The same effect was observed for Pd–base alloys, their curves were similar to the one of palladium. The ions released during chemical corrosion were non-precious metallic ions. Thereby Ni–Cr alloys were found to release the most ions. Au–Pt alloys showed the highest release of ions compared with other precious alloys but low compared with Ni–Cr. Electrochemical corrosion was more aggressive than chemical corrosion and every type of elements was etched, the higher the precious metal content, the higher the resistance to corrosion of the alloy.
Discussion
Using the recorded data, a classification system for electrochemical corrosion was developed and discussed to judge the results. Hereby were gold and zinc used as reference materials. The applied classification system defines five classes and it is proposed that alloys of class V are not acceptable. For chemical corrosion resistance, three classes were distinguished according to the quantity of metallic ions released and it is proposed that class III (100–1000 μg/cm2 week) is not acceptable. Palladium and Pd–base alloys showed a higher electrochemical and chemical corrosion resistance than gold.
Dental Materials
10.1016/j.dental.2006.11.030
Claire Manaranche
Helga Hornberger
eng
uncontrolled
Dental alloys
eng
uncontrolled
Precious alloys
eng
uncontrolled
Corrosion test
eng
uncontrolled
Resistance to corrosion
eng
uncontrolled
Classification
eng
uncontrolled
Ion release
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Lebenswissenschaften und Ethik
Labor Biomaterialien
532
2012
eng
2442
2455
7
8
article
0
--
--
--
Biomedical coatings on magnesium alloys
This review comprehensively covers research carried out in the field of degradable coatings on Mg and Mg alloys for biomedical applications. Several coating methods are discussed, which can be divided, based on the specific processing techniques used, into conversion and deposition coatings. The literature review revealed that in most cases coatings increase the corrosion resistance of Mg and Mg alloys. The critical factors determining coating performance, such as corrosion rate, surface chemistry, adhesion and coating morphology, are identified and discussed. The analysis of the literature showed that many studies have focused on calcium phosphate coatings produced either using conversion or deposition methods which were developed for orthopaedic applications. However, the control of phases and the formation of cracks still appear unsatisfactory. More research and development is needed in the case of biodegradable organic based coatings to generate reproducible and relevant data. In addition to biocompatibility, the mechanical properties of the coatings are also relevant, and the development of appropriate methods to study the corrosion process in detail and in the long term remains an important area of research.
Acta Biomaterialia
a review
10.1016/j.actbio.2012.04.012
peer-reviewed
Helga Hornberger
Sannakaisa Virtanen
Aldo R. Boccaccini
eng
uncontrolled
Magnesium alloyn
eng
uncontrolled
Biodegradable materials
eng
uncontrolled
Coatings
eng
uncontrolled
Conversion
eng
uncontrolled
Deposition
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
533
2012
eng
302
304
1
66
article
0
--
--
--
Characterization of electrophoretic chitosan coatings on stainless steel
Electrophoretic chitosan deposits on stainless steel AISI 316 L were produced and characterized. The coating quality (thickness, defectiveness, corrosion protection ability) was seen to depend on the electric field used for EPD. Corrosion studies in concentrated simulated body fluid (SBF5) demonstrated that the surface characteristics of AISI 316 L can be positively influenced by the chitosan coating.
Materials Letters
10.1016/j.matlet.2011.08.088
peer-reviewed
F. Gebhardt
Sigrid Seuss
Metehan C. Turhan
Helga Hornberger
Sannakaisa Virtanen
Aldo R. Boccaccini
eng
uncontrolled
Chitosan
eng
uncontrolled
Electrophoretic deposition
eng
uncontrolled
Biomaterials
eng
uncontrolled
Electrochemistry
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
541
1995
eng
559
562
article
0
--
--
--
Microstructure of a high strength alumina-glass composite combined with a diamond like carbon coating
We investigate the mechanical and microstructural properties of a diamond-like carbon coating (DLC) which is deposited by plasma enhanced chemical vapor deposition (PECVD) onto an alumina/aluminosilicate glass composite used for biomedical applications. Ball-on-ring tests yield a fracture strength that is essentially influenced by the surface topology/roughness. The surface topology of the coating is investigated by atomic force microscopy (AFM). Tribology tests and nanoindentation represent the wear resistance and hardness; these are properties that are mainly influenced by the microstructural properties of the DLC coating. This microstructure is investigated by transmission electron microscopy (TEM) and analyzed by parallel electron energy loss spectroscopy (PEELS). For the general applicability of the coated composite, the interfacial adhesion of the DLC coating on the comparably rough substrate (roughness amplitudes and wavelengths are in the micrometer range) is important. Therefore, we focus on TEM investigations that show the interface to be free of gaps and pores that we, together with a characteristic microstructure adjacent to the interface, relate to the excellent adhesion. The interlayer consists of a high density of SiC grains, part of them directly bound to the substrate, and part of them bound to other SiC grains. This interlayer is followed by an essentially different region of the coating as concerns the microstructure; this region consists of nanocrystalline diamond particles embedded in an amorphous carbon matrix. It is this heterogeneous microstructure to which we attribute (i) the good adhesion based upon the interface stabilizing SiC grains, and (ii) the high hardness and wear resistance based upon the diamond nanocrystals in the coating.
Electron Microscopy and Analysis
10.1557/JMR.1996.0244
Institute of Physics Conference Series ; 147
Helga Hornberger
Peter M. Marquis
Silke H. Christiansen
M. Albrecht
Horst P. Strunk
J. Franks
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
537
1996
eng
1934
1942
8
11
article
0
--
--
--
Mechanical properties and microstructural analysis of a diamond-like carbon coating on an alumina/glass composite
We investigate the mechanical and microstructural properties of a diamond-like carbon coating (DLC) which is deposited by plasma enhanced chemical vapor deposition (PECVD) onto an alumina/aluminosilicate glass composite used for biomedical applications. Ball-on-ring tests yield a fracture strength that is essentially influenced by the surface topology/roughness. The surface topology of the coating is investigated by atomic force microscopy (AFM). Tribology tests and nanoindentation represent the wear resistance and hardness; these are properties that are mainly influenced by the microstructural properties of the DLC coating. This microstructure is investigated by transmission electron microscopy (TEM) and analyzed by parallel electron energy loss spectroscopy (PEELS). For the general applicability of the coated composite, the interfacial adhesion of the DLC coating on the comparably rough substrate (roughness amplitudes and wavelengths are in the micrometer range) is important. Therefore, we focus on TEM investigations that show the interface to be free of gaps and pores that we, together with a characteristic microstructure adjacent to the interface, relate to the excellent adhesion. The interlayer consists of a high density of SiC grains, part of them directly bound to the substrate, and part of them bound to other SiC grains. This interlayer is followed by an essentially different region of the coating as concerns the microstructure; this region consists of nanocrystalline diamond particles embedded in an amorphous carbon matrix. It is this heterogeneous microstructure to which we attribute (i) the good adhesion based upon the interface stabilizing SiC grains, and (ii) the high hardness and wear resistance based upon the diamond nanocrystals in the coating.
Journal of Materials Research
10.1557/JMR.1996.0244
Silke H. Christiansen
M. Albrecht
Horst P. Strunk
Helga Hornberger
Peter M. Marquis
J. Franks
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
538
1996
eng
855
858
4
11
article
0
--
--
--
Microstructure of a high strength alumina glass composite
The morphology and microstructure of an Al2O3 glass composite (trade name In-Ceram, Vita Zahnfabrik) were studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite was produced by infiltration of a lanthanum-based glass throughout a porous Al2O3 body. This alumina body was formed by three classes of particles differing in size and shape: faceted particles typically ≤4 μm in diameter, platelets of average diameter 8 μm, 1.5 μm thickness, and small spheres 0.4 μm in diameter. The outstanding strength properties of the composite (600 MPa, ball-on-ring test) are a result of the high wetting capability of the glass phase on the Al2O3 surface. In addition, plastic strain relaxation in the faceted particles by dislocation formation compensates partially for residual stresses and impedes crack formation at the glass/Al2O3 interface.
Journal of Materials Research
10.1557/JMR.1996.0104
Helga Hornberger
Peter M. Marquis
Silke H. Christiansen
Horst P. Strunk
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
5250
2003
eng
34
36
SUPPL. 1
5
article
Univ. of Wales
Aberystwyth, Wales
0
--
--
--
A proposal for the classification of precious dental alloys according to their resistance to corrosion based on the iso 10271 standard
A lot of dental alloys are available on the market. Among these alloys, there are the conventional alloys, the so called casting alloys used without ceramics, the bonding alloys used with high fusing ceramics and the universal alloys used without or with low fusing ceramics. It is im portant to know the physical and mechanical properties of these materials but also their biocompatibility and their resistance to corrosion. Dental alloys are generally placed in the mouth for many years, they must not induce adverse biological reactions such as gingival swelling and erythema, mucosal pain and lichenoid reactions. Although these troubles are often caused not by the materials itself (1, 2), they can be induced by the metallic ions released during their corrosion. In order to decrease the risks to the health, it is necessary to study the corrosion of the dental alloys. Currently, the ISO 10271 Standard (3), describes 3 different corrosion tests: a static immersion test (chemical corrosion), an electrochemic al test and a tarnish test. However, there are no indications yet about the possible interpretation of test results. In this paper, we propose a method to compare and classify the dental alloys in relation to their chemical and electrochemical corrosion results. METHODS: The material tested are pure metals such as gold, palladium, silver, copper and zinc as well as dental alloys which are commercially sold (see Table 1). 54 different materials have been tested. A minimum of four samples of each material were tested by electrochemic al corrosio n and a minimum of three in chemical test. The samples were cast and prepared as indicated by the manufacturer and by the ISO 10271. For the electrochemical test, the samples are in the form of disks 11 mm in diameter. They are tested with a potentiostat/galvanostat Voltalab Model 21. For the chemical test, the samples are rectangular with the dimensions 35X10X1.7 mm. The solution used and the operating conditions are described in the ISO 10271. The concentration of metallic ions released is measured by Induced Coupled Plasma
European Cells and Materials
https://www.researchgate.net/publication/242728857_A_proposal_for_the_classification_of_precious_dental_alloys_according_to_their_resistance_to_corrosion_based_on_the_ISO_10271_standard
2022-08-20T07:06:56+00:00
sword
importuser
Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG
Claire Manaranche
Helga Hornberger
Fakultät Maschinenbau
Externe Publikationen
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Labor Biomaterialien
6123
2023
eng
1
21
10
article
MDPI
0
--
--
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In Vitro Analysis of Human Cartilage Infiltrated by Hydrogels and Hydrogel-Encapsulated Chondrocytes
Osteoarthritis (OA) is a degenerative joint disease causing loss of articular cartilage and structural damage in all joint tissues. Given the limited regenerative capacity of articular cartilage, methods to support the native structural properties of articular cartilage are highly anticipated. The aim of this study was to infiltrate zwitterionic monomer solutions into human OA-cartilage explants to replace lost proteoglycans. The study included polymerization and deposition of methacryloyloxyethyl-phosphorylcholine- and a novel sulfobetaine-methacrylate-based monomer solution within ex vivo human OA-cartilage explants and the encapsulation of isolated chondrocytes within hydrogels and the corresponding effects on chondrocyte viability. The results demonstrated that zwitterionic cartilage–hydrogel networks are formed by infiltration. In general, cytotoxic effects of the monomer solutions were observed, as was a time-dependent infiltration behavior into the tissue accompanied by increasing cell death and penetration depth. The successful deposition of zwitterionic hydrogels within OA cartilage identifies the infiltration method as a potential future therapeutic option for the repair/replacement of OA-cartilage extracellular suprastructure. Due to the toxic effects of the monomer solutions, the focus should be on sealing the OA-cartilage surface, instead of complete infiltration. An alternative treatment option for focal cartilage defects could be the usage of monomer solutions, especially the novel generated sulfobetaine-methacrylate-based monomer solution, as bionic for cell-based 3D bioprintable hydrogels.
Bioengineering
10.3390/bioengineering10070767
urn:nbn:de:bvb:898-opus4-61235
Corresponding author: Helga Hornberger
@articlearticle, author = Köck, Hannah and Striegl, Birgit and Kraus, Annalena and Zborilova, Magdalena and Christiansen, Silke and Schäfer, Nicole and Grässel, Susanne and Hornberger, H., year = 2023, month = 06, pages = 767, title = In Vitro Analysis of Human Cartilage Infiltrated by Hydrogels and Hydrogel-Encapsulated Chondrocytes, volume = 10, journal = Bioengineering, doi = 10.3390/bioengineering10070767
md5:259fefd1488ba80f897befdbf68256b4
2023-06-30T15:13:21+00:00
/tmp/phpviUmRr
bibtex
649ef1117e8476.40764068
Helga Hornberger
peer-reviewed
Creative Commons - CC BY - Namensnennung 4.0 International
Hannah Köck
Birgit Striegl
Annalena Kraus
Magdalena Zborilova
Silke H. Christiansen
Nicole Schäfer
Susanne Grässel
Helga Hornberger
eng
uncontrolled
osteoarthritis
eng
uncontrolled
human articular cartilage
eng
uncontrolled
chondrocytes
eng
uncontrolled
hydrogels
eng
uncontrolled
zwitterionic monomers
eng
uncontrolled
infiltration
Fakultät Maschinenbau
Regensburg Center of Biomedical Engineering - RCBE
Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Lebenswissenschaften und Ethik
Corresponding author der OTH Regensburg
Publikationsfonds der OTH Regensburg
Labor Biomaterialien
Ostbayerische Technische Hochschule Regensburg
https://opus4.kobv.de/opus4-oth-regensburg/files/6123/Hornberger_bioengineering-10-00767.pdf
2449
2022
eng
8
19
1
73
article
Wiley
0
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Bioactivity and corrosion behavior of magnesium barrier membranes
In the current research, magnesium and its alloys have been intensively studied as resorbable implant materials. Magnesium materials combine their good mechanical properties with bioactivity, which make them interesting for guided bone regeneration and for the application as barrier membranes. In this study, the in vitro degradation behavior of thin magnesium films was investigated in cell medium and simulated body fluid. Three methods were applied to evaluate corrosion rates: measurements of (i) the gaseous volume evolved during immersion, (ii) volume change after immersion, and (iii) polarization curves. In this comparison, measurements of H2 development in Dulbecco's modified Eagle's medium showed to be the most appropriate method, exhibiting a corrosion rate of 0.5 mm·year−1. Observed oxide and carbon contamination have a high impact on controlled degradation, suggesting that surface treatment of thin foils is necessary. The bioactivity test showed positive results; more detailed tests in this area are of interest.
Materials and Corrosion
10.1002/maco.202112385
urn:nbn:de:bvb:898-opus4-24499
Corresponding author: Helga Hornberger
2022-01-21T08:21:02+00:00
sword
importuser
peer-reviewed
Helga Hornberger
Creative Commons - CC BY-NC-SA - Namensnennung - Nicht kommerziell - Weitergabe unter gleichen Bedingungen 4.0 International
Helga Hornberger
Hannah Kissel
Birgit Striegl
Matthias Kronseder
Florian Vollnhals
Silke H. Christiansen
Fakultät Maschinenbau
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Hybrid Open Access - OA-Veröffentlichung in einer Subskriptionszeitschrift/-medium
Corresponding author der OTH Regensburg
DEAL Wiley
Labor Biomaterialien
Ostbayerische Technische Hochschule Regensburg
https://opus4.kobv.de/opus4-oth-regensburg/files/2449/Hornberger_Materials_Corrosion_2021.pdf
6825
2023
eng
Journal Pre-proof
article
Elsevier
0
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Corrosion behaviour of electropolished magnesium materials
Although magnesium and its alloys are promising candidates as biodegradable implant materials, the tendency for localized corrosion mechanism in physiological environment limit their biomedical application. Electropolishing is an attractive strategy for improving the corrosion behaviour of metals, but it is still largely unexplored in magnesium materials. In this study, the characterization of electropolished surfaces of AM50 and pure magnesium was performed, focussing on their in vitro degradation behaviour in cell medium. Corrosion rates were evaluated using potentiodynamic polarisation. The surface morphology before and after the onset of corrosion was investigated by scanning electron microscopy and confocal laser scanning microscopy. The presented electropolishing process led to improved surface performances, observable by significantly lower corrosion rates (0.08 mm·year-1 in Dulbecco's modified Eagle's medium), lower arithmetical mean height (0.05 µm), lower water contact angle (25-35°) and lower micro hardness (35-50 HV 0.1) compared to mechanically and chemically treated surfaces. MgO/Mg(OH)2 could be detected on electropolished surfaces. The localized corrosion mode could be reduced, but not entirely prevented. Electropolishing shows great potential as post-treatment of magnesium-based components, but detailed tests of the long-term corrosion behaviour are an important area of future research.
Materials Today Communications
10.1016/j.mtcomm.2023.107983
urn:nbn:de:bvb:898-opus4-68254
Corresponding author: Helga Hornberger
2024-01-02T15:51:32+00:00
sword
importuser
Creative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International
Jessica Kloiber
Ulrich Schultheiß
Lamborghini Sotelo
George Sarau
Silke Christiansen
Sarkis Gavras
Norbert Hort
Helga Hornberger
eng
uncontrolled
biomedical application
eng
uncontrolled
corrosion behaviour
eng
uncontrolled
electropolishing
eng
uncontrolled
magnesium alloy
eng
uncontrolled
pure magnesium
eng
uncontrolled
surface characterization
Fakultät Maschinenbau
Hornberger, Helga (Prof. Dr.) - Labor Biomaterialien
Produktion und Systeme
Hybrid Open Access - OA-Veröffentlichung in einer Subskriptionszeitschrift/-medium
Corresponding author der OTH Regensburg
Publikationsfonds der OTH Regensburg
Labor Biomaterialien
Ostbayerische Technische Hochschule Regensburg
https://opus4.kobv.de/opus4-oth-regensburg/files/6825/Hornberger_Materials_today_2023.pdf