Change search
Refine search result
1 - 38 of 38
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF, Keramer.
    Zirconia in applications with bone contact2016Conference paper (Other academic)
  • 2.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Lyckfeldt, Ola
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Johansson, Emil
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Visible-Light CurableCeramic Suspensions for Additive Manufacturing of Dense Ceramic Parts2016Conference paper (Other academic)
  • 3.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Shen, J.Z.
    Stockholm University.
    Defect Minimization in Prosthetic Ceramics2014In: Advanced Ceramics for Dentistry, Elsevier Inc. , 2014, p. 359-373Chapter in book (Refereed)
    Abstract [en]

    The mechanical reliability and aesthetic appearance of ceramic dental prostheses are strongly influenced by the presence of defects. When several processes are used during fabrication of ceramic dental prostheses, additional defects are unavoidably introduced in each process step; these are in addition to the ones that already exist in raw materials. To avoid the degeneration of material performance by the accumulated defect population, process optimization is needed to minimize the defects introduced. Standardized mechanical evaluations are usually performed on samples with carefully prepared surfaces in order to minimize the influence from the defects usually induced by fabrication processes. The results from such mechanical evaluation indicate the strength level that is achievable by the material with the given population of bulk defects. In order to avoid a reduction in the performance of the ceramic material by the additional defects normally induced by the fabrication process, it must be understood how these defects are introduced, and solutions must be found to reduce their size and frequency through modifications of the material and processes. The aim of this chapter is to elucidate the sources of defects that are common for ceramic dental prostheses and to determine how to minimize them. © 2014 Elsevier Inc. All rights reserved.

  • 4.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Shen, Z.
    Stockholm University.
    Effects of granule density on strength and granule related defects in zirconia2012In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, no 11, p. 2653-2659Article in journal (Refereed)
    Abstract [en]

    A suspension of zirconia powder (TZ3YSE) with a solids loading of 50. vol% was prepared by ball milling. Binders were added and some of the suspension was diluted to 40, 30 and 20. vol% before freeze granulation was performed. A spray dried material (TZ3YSEB) was used as a reference. The pore size distribution of the different granules was evaluated and from the microstructure it was shown that inhomogeneities were present in both the freeze granulated as well as in the spray dried granules. In addition, the density, microstructure as well as the strength of sintered materials prepared from the granules were studied. The results showed that a high green density or sintered density was not sufficient in order to achieve a high strength material. It was further shown that the strength was significantly influenced by the granule density and not by the inhomogeneities found in the granules. © 2012.

  • 5.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Tönnäng, Lenny
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    The effect of softmachining parameters on the mechanical strength of zirconia2015Conference paper (Other academic)
  • 6.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Venturini, Francesca
    ZHAW School of Engineering.
    Schönherr, Veit
    ZHAW School of Engineering .
    Rey, Julien
    ZHAW School of Engineering.
    Characterization oflight-gas interaction in strongly-scattering nanoporous materials and itsimplications for tunable diode laser absorption spectroscopy2016Conference paper (Other academic)
  • 7.
    Altmann, Brigitte
    et al.
    University of Freiburg, Germany.
    Karygianni, Lamprini
    University of Freiburg, Germany.
    Al-Ahmad, Ali
    University of Freiburg, Germany.
    Butz, Frank
    University of Freiburg, Germany.
    Bächle, Maria
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Fürderer, Tobias
    Courtois, Nicolas
    Palmero, Paola
    Politecnico di Torino, Italy.
    Follo, Marie
    University of Freiburg, Germany.
    Chevalier, Jérôme
    Université de Lyon, France.
    Steinberg, Thorsten
    University of Freiburg, Germany.
    Kohal, Ralf Joachim
    University of Freiburg, Germany.
    Assessment of Novel Long-Lasting Ceria-Stabilized Zirconia-Based Ceramics with Different Surface Topographies as Implant Materials2017In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 27, no 40, article id 1702512Article in journal (Refereed)
    Abstract [en]

    The development of long-lasting zirconia-based ceramics for implants, which are not prone to hydrothermal aging, is not satisfactorily solved. Therefore, this study is conceived as an overall evaluation screening of novel ceria-stabilized zirconia-alumina-aluminate composite ceramics (ZA8Sr8-Ce11) with different surface topographies for use in clinical applications. Ceria-stabilized zirconia is chosen as the matrix for the composite material, due to its lower susceptibility to aging than yttria-stabilized zirconia (3Y-TZP). This assessment is carried out on three preclinical investigation levels, indicating an overall biocompatibility of ceria-stabilized zirconia-based ceramics, both in vitro and in vivo. Long-term attachment and mineralized extracellular matrix (ECM) deposition of primary osteoblasts are the most distinct on porous ZA8Sr8-Ce11p surfaces, while ECM attachment on 3Y-TZP and ZA8Sr8-Ce11 with compact surface texture is poor. In this regard, the animal study confirms the porous ZA8Sr8-Ce11p to be the most favorable material, showing the highest bone-to-implant contact values and implant stability post implantation in comparison with control groups. Moreover, the microbiological evaluation reveals no favoritism of biofilm formation on the porous ZA8Sr8-Ce11p when compared to a smooth control surface. Hence, together with the in vitro in vivo assessment analogy, the promising clinical potential of this novel ZA8Sr8-Ce11 as an implant material is demonstrated. 

  • 8.
    Altmann, Brigitte
    et al.
    University Medical Center Freiburg, Germany.
    Rabel, Kerstin
    University Medical Center Freiburg, Germany.
    Kohal, Ralf J.
    University Medical Center Freiburg, Germany.
    Proksch, Susanne
    University Medical Center Freiburg, Germany.
    Tomakidi, Pascal
    University Medical Center Freiburg, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Bernsmann, Falk
    NTTF Coatings GmbH, Germany.
    Palmero, Paola
    Politecnico di Torino, Italy.
    Fürderer, Tobias
    MOESCHTER GROUP Holding GmbH, Germany.
    Steinberg, Thorsten
    University Medical Center Freiburg, Germany.
    Cellular transcriptional response to zirconia-based implant materials2017In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 33, no 2, p. 241-255Article in journal (Refereed)
    Abstract [en]

    Objective To adequately address clinically important issues such as osseointegration and soft tissue integration, we screened for the direct biological cell response by culturing human osteoblasts and gingival fibroblasts on novel zirconia-based dental implant biomaterials and subjecting them to transcriptional analysis. Methods Biomaterials used for osteoblasts involved micro-roughened surfaces made of a new type of ceria-stabilized zirconia composite with two different topographies, zirconium dioxide, and yttria-stabilized zirconia (control). For fibroblasts smooth ceria- and yttria-stabilized zirconia surface were used. The expression of 90 issue-relevant genes was determined on mRNA transcription level by real-time PCR Array technology after growth periods of 1 and 7 days. Results Generally, modulation of gene transcription exhibited a dual dependence, first by time and second by the biomaterial, whereas biomaterial-triggered changes were predominantly caused by the biomaterials’ chemistry rather than surface topography. Per se, modulated genes assigned to regenerative tissue processes such as fracture healing and wound healing and in detail included colony stimulating factors (CSF2 and CSF3), growth factors, which regulate bone matrix properties (e.g. BMP3 and TGFB1), osteogenic BMPs (BMP2/4/6/7) and transcription factors (RUNX2 and SP7), matrix collagens and osteocalcin, laminins as well as integrin ß1 and MMP-2. Significance With respect to the biomaterials under study, the screening showed that a new zirconia-based composite stabilized with ceria may be promising to provide clinically desired periodontal tissue integration. Moreover, by detecting biomarkers modulated in a time- and/or biomaterial-dependent manner, we identified candidate genes for the targeted analysis of cell-implant bioresponse during biomaterial research and development.

  • 9. Anderud, J
    et al.
    Abrahamsson, P
    Jimbo, R
    Isaksson, S
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Malmström, J
    Naito, Y
    Wennerberg, A
    Guided bone augmentation using ceramic space-maintaining devices: The impact of chemistry2015In: Clinical, Cosmetic and Investigational Dentistry, ISSN 11791357, Vol. 7, p. 45-53Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to evaluate histologically, whether vertical bone augmentation can be achieved using a hollow ceramic space maintaining device in a rabbit calvaria model. Furthermore, the chemistry of microporous hydroxyapatite and zirconia were tested to determine which of these two ceramics are most suitable for guided bone generation. 24 hollow domes in two different ceramic materials were placed subperiosteal on rabbit skull bone. The rabbits were sacrificed after 12 weeks and the histology results were analyzed regarding bone-to-material contact and volume of newly formed bone. The results suggest that the effect of the microporous structure of hydroxyapatite seems to facilitate for the bone cells to adhere to the material and that zirconia enhance a slightly larger volume of newly formed bone. In conclusion, the results of the current study demonstrated that ceramic space maintaining devices permits new bone formation and osteoconduction within the dome. © 2015 Anderud et al.

  • 10.
    Anderud, J.
    et al.
    University Malmö.
    Jimbo, R.
    University Malmö.
    Abrahamsson, P.
    Region Halland.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Malmström, J.
    Region Halland.
    Wennerberg, A.
    Malmö University.
    The impact of surface roughness and permeability in hydroxyapatite bone regeneration membranes2015In: Clinical Oral Implants Research, ISSN 0905-7161, E-ISSN 1600-0501Article in journal (Refereed)
    Abstract [en]

    Background: One of the crucial aspects in guided bone regeneration is the space maintenance. This is normally created by a membrane, which should primarily be accepted by the surrounding tissues without causing any adverse reactions. The impact of surface topography, biological acceptance as well as permeability of these membranes has been carefully discussed in the literature. Purpose: The purpose of this study was to evaluate histologically the bone forming properties inside of hollow hydroxyapatite space-maintaining devices with different inner surfaces and different permeabilities in an animal calvaria model in vivo. Materials and methods: A total of 36 hollow domes with three different designs made of hydroxyapatite were surgically attached to the skulls of rabbits. Group 1 had a moderately rough inner surface. Group 2 had a smooth inner surface. Group 3 had the same properties as Group 1 but had macroscopic holes on the top. The domes were left to heal for 12 weeks and were then processed for undecalcified ground sectioning. Histological evaluations were performed using a light microscope and scanning electron microscopy. The bone-implant contact (BIC) percentage along the device was calculated. Results: The median percentage of BIC was higher for Group 1 compared with Group 2 (P = 0.004). Group 1 produced a larger median BIC compared with Group 3 (P < 0.0001). Conclusions: Within the limits of this preclinical study, these findings suggest that a moderately rough inner surface of a ceramic membrane along with a non-permeable device produces more bone than a smooth inner surface. © 2015 John Wiley & Sons A/S.

  • 11.
    Brinkfeldt, Klas
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Amen, Rafael
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Tegehall, Per-Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Johander, Per
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Andersson, Dag
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Thermo-mechanical simulations and measurements on high temperature interconnections2011In: 12th Int. Conf. on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2011, 2011, article id 5765772Conference paper (Refereed)
    Abstract [en]

    In order to place sensors or electronics in very high temperature environments, new materials and methods for interconnection are required. A comparative study between different electrical interconnection methods for very high operation temperatures (500 °C - 800 °C) is presented. Thermo-mechanical simulations and characterization of samples of the interconnection types during high temperature exposure are presented. The results of the thermo-mechanical simulations showed that stresses are low in a connection system based on liquid interconnection. This system, however, proved to be difficult to realize due to problems with oxides and sealing of the metallic liquid. Modeling of an interconnection based purely on mechanical pressure without any solder or metallic bond showed high stress. This was also confirmed during high temperature exposure where the connection failed. High stress was also predicted for an interconnection based on nano-Ag paste. The high temperature tests, however, showed promising results at 800 °C for over 100 hours. © 2011 IEEE.

  • 12.
    Brinkfeldt, Klas
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Formánek, J.
    Czech Technical University.
    Laposa, A.
    Czech Technical University.
    Jakovenko, J.
    Czech Technical University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Johander, Per
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Simulations of a high temperature pressure sensor packaging and interconnection2012In: EuroSimE 2012: 13th International Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, 2012Conference paper (Refereed)
    Abstract [en]

    Modeling and thermal cycling of a high temperature pressure sensor packaging is presented. The packaging is based on the green-state milling of alumina to the desired geometry and conduits for the electrical conductors, followed by sintering of the ceramics with the electrical conductors inside. The electrical interconnections are based on silver. For short term operation, the package can be exposed to temperatures close to the melting temperature of silver (961°C). It has shown operational in temperature cycling above 600°C for more than 1800 hours. Modeling of the package show that the stress in the electrical interconnections are close to the yield stress of silver at 20°C. The stress free temperature in the modeling was set to 850°C. Temperature induced stress and strains in the packaging and a fatigue simulation are performed. The package is generic and can be converted to fit most geometries and high temperature applications. © 2012 IEEE.

  • 13.
    Dehestani, M.
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Phase stability and mechanical properties of zirconia and zirconia composites2013In: International Journal of Applied Ceramic Technology, ISSN 1546542X, Vol. 10, no 1, p. 129-141Article in journal (Refereed)
    Abstract [en]

    Monolithic zirconia materials (3Y-TZP, 10Ce-TZP, and 12Ce-TZP) and their composites with 30 vol% alumina were produced. Low-temperature aging degradation (LTAD) and mechanical properties of materials were investigated. For assessment of phase stability in the materials, aging experiments were performed in water at 90°C for 32, 64, and 128 days. The aging phenomenon was characterized and monitored using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Four-point bending was used to determine the flexural strength of materials before and after aging treatment in water at 90°C for 2, 4, and 6 months. The aging experiments resulted in different phase transformation rates for the materials studied. The 12Ce-TZP containing materials showed the highest resistance to low-temperature aging and 3Y-TZP containing materials showed the highest bending strength. When compared, no change in flexural strength was observed between the materials not exposed to aging and the aged materials. © 2012 The American Ceramic Society.

  • 14.
    Dehestani, Mahdi
    et al.
    Purdue University, USA.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Stanciu, Lia A.
    Purdue University, USA.
    Mechanical properties and corrosion behavior of powder metallurgy iron-hydroxyapatite composites for biodegradable implant applications2016In: Materials and Design, ISSN 0264-1275, Vol. 109, p. 556-569Article in journal (Refereed)
    Abstract [en]

    Nine Fe–HA composites were fabricated via powder metallurgy method by varying the amount (2.5, 5, 10 wt%) and particle size (&lt; 1 Όm, 1–10 Όm, 100–200 Όm) of hydroxyapatite (HA) as a bioactive phase in the iron (Fe) matrix. X-ray diffraction did not detect any phase changes in HA after the sintering process. Uniaxial tensile tests measured the strengths of the composites. Polarization and immersion tests estimated the corrosion rates (CR). Yield strength, tensile strength, and ductility of the composites decreased with increasing HA content and decreasing HA particle size, whereas their corrosion rates increased. The strongest composite was Fe–2.5 wt% HA (100–200 Όm) with σy = 81.7 MPa, σu = 130.1 MPa, fracture strain of 4.87%, and CR = 0.23 mmpy. The weakest composite was Fe–10 wt% HA (&lt; 1 Όm) which did not exhibit plastic deformation, fractured at σu = 16.1 MPa with 0.11% strain, and showed the highest CR of 1.07 mmpy. This study demonstrates how the relative particle size between Fe and HA determines the mechanical and corrosion properties of Fe–HA composites, thereby aiding in enhancing future resorbable implant designs. The model can also be used when designing other bioactive composites (i.e. Ti–HA, Mg–HA) via powder metallurgy.

  • 15.
    Dehestani, Mahdi
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Ilver, L.
    Chalmers University of Technology.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Enhancing the bioactivity of zirconia and zirconia composites by surface modification2012In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 100 B, no 3, p. 832-840Article in journal (Refereed)
    Abstract [en]

    Among bioceramics, zirconia (ZrO 2) and alumina (Al 2O 3) possess exceptional mechanical properties suitable for load-bearing and wear-resistant applications but the poor bioactivity of these materials is the major concern when bonding and integration to the living bone are desired. This article investigates two different approaches and their underlying mechanisms to improve the bioactivity of zirconia (3Y-TZP) and a zirconia composite with alumina (10Ce-TZP/Al 2O 3). Chemical treatment approach applied on 3Y-TZP where the substrates were soaked in 5M H 3PO 4 to create chemically functional groups on the surface for inducing apatite nucleation. X-ray photoelectron spectroscopy (XPS) was used to detect chemical changes and X-ray diffraction (XRD) to monitor phase changes on the surface before and after acid treatment. Alternate soaking approach applied on 10Ce-TZP/Al 2O 3 consisted of soaking the composite substrates in CaCl 2 and Na 2HPO 4 solutions alternately to make a precursor for apatite formation. The bioactivity was evaluated by apatite-forming ability of surface-treated materials in simulated body fluid (SBF). Both methods resulted in the formation of hydroxyapatite on the surface of materials; however, alternate soaking approach showed to be a simpler, faster, and more effective method than the chemical treatment approach for enhancing the bioactivity of zirconia materials. © 2012 WILEY PERIODICALS, INC.

  • 16.
    Dehestani, Mahdi
    et al.
    Purdue University, USA.
    Zemlyanov, Dmitry Yu
    Purdue University, USA.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Stanciu, Lia A.
    Purdue University, USA.
    Improving bioactivity of inert bioceramics by a novel Mg-incorporated solution treatment2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 425, p. 564-575Article in journal (Refereed)
    Abstract [en]

    Zirconia/alumina ceramics possess outstanding mechanical properties for dental and orthopedic applications, but due to their poor surface bioactivities they exhibit a weak bone-bonding ability. This work proposes an effective 30-min solution treatment which could successfully induce formation of bone-like apatite on the surface of 3Y-TZP and a ternary composite composed of yttria-stabilized zirconia, ceria-stabilized zirconia, and alumina (35 vol% 3Y-TZP + 35 vol% 12Ce-TZP + 30 vol% Al2O3) after 3 weeks immersion in simulated body fluid (SBF). XRD was used for phase identification in the ceramic materials. The influence of solution treatment on the surface chemistry and its role on apatite formation were investigated via SEM, EDS and XPS. In vitro apatite-forming ability for the solution-treated and untreated samples of the composite and individual substrates of 3Y-TZP, 12Ce-TZP, and Al2O3 was evaluated by immersion in SBF. Apatite crystals were formed only on 3Y-TZP and composite substrates, implying that it is mainly the 3Y-TZP constituent that contributes to the bioactivity of the composite. Further, it was found from the XPS analysis that the zirconia material with higher phase stability (12Ce-TZP) produced less Zr–OH functional groups on its surface after solution treatment which accounts for its weaker bioactivity compared to 3Y-TZP. 

  • 17.
    Fornabaio, Marta
    et al.
    Politecnico di Torino, Italy; EPFL École Polytechnique Fédérale de Lausanne, Switzerland.
    Reveron, Helen
    INSA Lyon, France.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Montanaro, Laura
    Politecnico di Torino, Italy.
    Chevalier, Jérôme
    INSA Lyon, France.
    Palmero, Paola
    Politecnico di Torino, Italy.
    Design and development of dental ceramics: Examples of current innovations and future concepts2017In: Advances in Ceramic Biomaterials: Materials, Devices and Challenges / [ed] Palmero, P., Cambier, F., De Barra, E., Elsevier Inc. , 2017, 1, p. 355-389Chapter in book (Other academic)
  • 18.
    Fäldt, J.
    et al.
    Nobel Biocare AB.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Future use of ceramics in dentistry2008In: A Global Road Map for Ceramic Materials and Technologies: Forecasting the Future of Ceramics, International Ceramic Federation - 2nd International Congress on Ceramics, ICC 2008, Final Programme, 2008Conference paper (Refereed)
    Abstract [en]

    The use of dental ceramics has an important social aspect, as a lot of people are in great need of new teeth but the cost is often high. The development of the Procera® system by Nobel Biocare was a solution to this where the production of prefabricated crowns were centralized to reduce the cost of the products. The production processes are continuously developed to improve the reliability of both the materials used as well as for those materials that will be introduced in the near future. For all these new materials an increased knowledge is needed and a large effort is made to predict the behaviour concerning both the in vivo behaviour and the long-term stability. Other challenges are related to the aesthetics, where it would be desired if a suitable combination of colour, translucency and lustre could be selected without affecting other important properties and to improve the interactions between the material and the biology.

  • 19. Grandfield, K.
    et al.
    Palmquist, A.
    Ericson, F.
    Malmström, J.
    Emanuelsson, L.
    Slotte, C.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Botton, G. A.
    Thomsen, P.
    Engqvist, H.
    Bone Response to Free-Form Fabricated Hydroxyapatite and Zirconia Scaffolds: A Transmission Electron Microscopy Study in the Human Maxilla2012In: Clinical Implant Dentistry and Related Research, ISSN 15230899, Vol. 14, no 3, p. 461-469Article in journal (Refereed)
    Abstract [en]

    Background: Understanding the interfacial reactions to synthetic bone regenerative scaffolds in vivo is fundamental for improving osseointegration and osteogenesis. Using transmission electron microscopy, it is possible to study the biological response of hydroxyapatite (HA) and zirconia (ZrO2) scaffolds at the nanometer scale. Purpose: In this study, the bone-bonding abilities of HA and ZrO2 scaffolds produced by free-form fabrication were evaluated in the human maxilla at 3 months and 7 months. Materials and Methods: HA and ZrO2 scaffolds (ø: 3mm) were implanted in the human maxilla, removed with surrounding bone, embedded in resin, and sectioned. A novel focused ion beam (FIB) sample preparation technique enabled the production of thin lamellae for study by scanning transmission electron microscopy. Results: Interface regions were investigated using high-angle annular dark-field imaging and energy-dispersive X-ray spectroscopy analysis. Interfacial apatite layers of 80nm and 50nm thickness were noted in the 3- and 7-month HA samples, respectively, and bone growth was discovered in micropores up to 10μm into the samples. Conclusions: The absence of an interfacial layer in the ZrO2 samples suggest the formation of a direct contact with bone, while HA, which bonds through an apatite layer, shows indications of resorption with increasing implantation time. This study demonstrates the potential of HA and ZrO2 scaffolds for use as bone regenerative materials.

  • 20.
    Johansson, Emil
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Lidström, Oscar
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Lyckfeldt, Ola
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Jan, Johansson
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Influence of Resin Composition on the Defect Formation in Alumina Manufactured by Stereolithography2017In: Materials, ISSN ISSN 1996-1944, Vol. 10, no 2, article id 138Article in journal (Refereed)
    Abstract [en]

    Stereolithography (SL) is a technique allowing additive manufacturing of complex ceramic parts by selective photopolymerization of a photocurable suspension containing photocurable monomer, photoinitiator, and a ceramic powder. The manufactured three-dimensional object is cleaned and converted into a dense ceramic part by thermal debinding of the polymer network and subsequent sintering. The debinding is the most critical and time-consuming step, and often the source of cracks. In this study, photocurable alumina suspensions have been developed, and the influence of resin composition on defect formation has been investigated. The suspensions were characterized in terms of rheology and curing behaviour, and cross-sections of sintered specimens manufactured by SL were evaluated by SEM. It was found that the addition of a non-reactive component to the photocurable resin reduced polymerization shrinkage and altered the thermal decomposition of the polymer matrix, which led to a reduction in both delamination and intra-laminar cracks. Using a non-reactive component that decomposed rather than evaporated led to less residual porosity.

  • 21.
    Johansson, L.-A.
    et al.
    University of Gothenburg.
    Isaksson, S.
    Malmö University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Lindh, C.
    Malmö University.
    Sennerby, L.
    University of Gothenburg.
    Bone Regeneration Using a Hollow Hydroxyapatite Space-Maintaining Device for Maxillary Sinus Floor Augmentation - A Clinical Pilot Study2012In: Clinical Implant Dentistry and Related Research, ISSN 1523-0899, E-ISSN 1708-8208, Vol. 14, no 4, p. 575-584Article in journal (Refereed)
    Abstract [en]

    Background: The mere lifting of the maxillary sinus membrane by implants protruding into the sinus cavity allows the establishment of a void space for blood clot and new bone formation. Purpose: To evaluate bone formation by using a spherical, hollow, and perforated hydroxyapatite space-maintaining device (HSMD) in a two-stage sinus lift procedure where residual alveolar bone height was ≤2mm. Material and Methods: Spherical, hollow, and perforated HSMDs with a diameter of 12mm were manufactured for this pilot study. Three patients with a residual bone height of 1-2mm, as verified clinically and radiographically, and in need of a sinus augmentation procedure prior to implant installation were selected for the study. The HSMD and bone formation was evaluated by cone beam computerized tomography (CBCT) 6months after augmentation procedure. Implants were installed 6 to 9 months after augmentation. The implant sites were prepared by a trephine drill to obtain a specimen of HSMD and bone for histological evaluation. After implant installation, the condition of the sinus membrane adjacent to the HSMD was evaluated endoscopically. After an additional 8weeks, fixed partial prostheses were fabricated. Results: Bone formation verified by CBCT was found around and inside the device in all three patients after 6months. Despite the fact that residual bone before augmentation was ≤2mm, 12-mm-long implants with diameter of 4.8mm could be inserted with preservation of an intact and healthy sinus membrane verified endoscopically. Bone formation inside HSMDs was noted histologically in two out of three HSMDs. Implants were stable and without any marginal bone loss after 1year of prosthetic loading. Conclusion: A spherical, hollow, and perforated HSMD used in sinus lift procedures can produce a void space for blood clot and new bone formation and subsequent implant installation. © 2010 Wiley Periodicals, Inc.

  • 22.
    Karygianni, L.
    et al.
    University of Freiburg.
    Jähnig, A.
    University of Freiburg.
    Schienle, S.
    University of Freiburg.
    Bernsmann, F.
    NTTF Coatings GmbH.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Kohal, R.J.
    University of Freiburg.
    Chevalier, J.
    University of Lyon.
    Hellwig, E.
    University of Freiburg.
    Al-Ahmad, A.
    University of Freiburg.
    Initial bacterial adhesion on different yttria-stabilized tetragonal zirconia implant surfaces in vitro2013In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 6, no 12, p. 5659-5674Article in journal (Refereed)
    Abstract [en]

    Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2h: 3mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO2) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential. © 2013 by the authors.

  • 23.
    Li, Duan
    et al.
    Stockholm University, Sweden; National University of Defence, China.
    Liu, Yongsheng
    Stockholm University, Sweden.
    Zhong, Yuan
    Stockholm University, Sweden.
    Liu, Leifeng
    Stockholm University, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Shen, Zhijian
    Stockholm University, Sweden.
    Dense and strong ZrO2 ceramics fully densified in <15 min2018In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761Article in journal (Refereed)
    Abstract [en]

    Crack-free zirconia ceramics were consolidated via sintering by intense thermal radiation (SITR) approach at 1600–1700°C for 3–5 min. The resulted ceramic bulks can achieve a relative density up to 99.6% with a grain size of 300–1200 nm. Their bending strength, Vickers hardness and indentation toughness values are up to 1244 ± 139 MPa, 13.3 ± 0.3 GPa and 5.5 ± 0.1 MPa m1/2, respectively. Quantitative Raman and XRD analysis show the presence of minor m phase on the natural surface (&lt;7%), fracture surface (&lt;10%) and indentation areas (&lt;15%). It reveals that the SITR method is efficient for rapidly manufacturing zirconia ceramics with desired density, fine grained microstructure and good mechanical properties that are strongly demanded in dental applications. 

  • 24.
    Malmström, Johan
    et al.
    Maxillofacial Unit Halmstad, Sweden.
    Anderud, Jonas
    Maxillofacial Unit Halmstad, Sweden.
    Abrahamsson, Peter
    Maxillofacial Unit Halmstad, Sweden.
    Wälivaara, Dan Åke
    Maxillofacial Unit Halmstad, Sweden.
    Isaksson, Sten G
    Maxillofacial Unit Halmstad, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Guided bone regeneration using individualized ceramic sheets2016In: International Journal of Oral and Maxillofacial Surgery, ISSN 0901-5027, E-ISSN 1399-0020, ISSN 0901-5027, Vol. 45, no 10, p. 1246-1252Article in journal (Refereed)
    Abstract [en]

    Guided bone regeneration (GBR) describes the use of membranes to regenerate bony defects. A membrane for GBR needs to be biocompatible, cell-occlusive, non-toxic, and mouldable, and possess space-maintaining properties including stability. The purpose of this pilot study was to describe a new method of GBR using individualized ceramic sheets to perfect bone regeneration prior to implant placement; bone regeneration was assessed using traditional histology and three-dimensional (3D) volumetric changes in the bone and soft tissue. Three patients were included. After full-thickness flap reflection, the individualized ceramic sheets were fixed. The sites were left to heal for 7 months. All patients were evaluated preoperatively and at 7 months postoperative using cone beam computed tomography and 3D optical equipment. Samples of the regenerated bone and soft tissue were collected and analyzed. The bone regenerated in the entire interior volume of all sheets. Bone biopsies revealed newly formed trabecular bone with a lamellar structure. Soft tissue biopsies showed connective tissue with no signs of an inflammatory response. This was considered to be newly formed periosteum. Thus ceramic individualized sheets can be used to regenerate large volumes of bone in both vertical and horizontal directions independent of the bone defect and with good biological acceptance of the material. © 2016 International Association of Oral and Maxillofacial Surgeons

  • 25.
    Nakamura, K.
    et al.
    Tohoku University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Milleding, P.
    Göteborg University.
    Kanno, T.
    Tohoku University Graduate School of Dentistry.
    Örtengren, U.
    Göteborg University.
    Influence of grain size and veneer firing process on the flexural strength of zirconia ceramics2012In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 120, no 3, p. 249-254Article in journal (Refereed)
    Abstract [en]

    The aim of the present investigation was to study the influence of grain size on the strength of yttria-stabilized zirconia upon exposure to an additional heat treatment, mimicking the veneering process. The green bodies of zirconia discs prepared by cold isostatic pressing were sintered at 1,425, 1,500, or 1,575°C to customize the grain size. The disc-shaped specimens were highly polished and then processed with or without additional heat treatments (five times at 850-930°C). Ten specimens from each treatment group were subjected to a biaxial flexural strength test according to the ISO 6872 standard. The grain size of the specimens was analyzed by the mean linear intercept technique using scanning electron microscopy. It was demonstrated that the mechanical strength of zirconia ceramics was not reduced by the veneer firing processes when polished specimens were used, but the strength was found to decrease with increasing grain size. The raw materials and the sintering process used should be selected appropriately to avoid grain coarsening because it was found that the strength was influenced by large grains. © 2012 Eur J Oral Sci.

  • 26.
    Nakamura, K.
    et al.
    University of Gothenburg.
    Harada, A.
    Tohoku University Graduate School of Dentistry.
    Ono, M.
    Japan Fine Ceramics Co..
    Shibasaki, H.
    Japan Fine Ceramics Co..
    Kanno, T.
    Tohoku University Graduate School of Dentistry.
    Niwano, Y.
    Tohoku University Graduate School of Dentistry.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Milleding, P.
    University of Gothenburg.
    Örtengren, U.
    University of Gothenburg.
    Effect of low-temperature degradation on the mechanical and microstructural properties of tooth-colored 3Y-TZP ceramics2016In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 53, p. 301-311Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to evaluate the effects of low-temperature degradation (LTD) induced by autoclaving on the mechanical and microstructural properties of tooth-colored 3mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP). In total, 162 disc-shaped 3Y-TZP specimens were prepared. Two-thirds of the specimens were shaded by either the infiltration or powder mixing methods while the remaining specimens were used without coloring. The specimens were autoclaved at 134°C for 0, 10, and 100h to induce LTD (n=18 for each group). Chemical compositions were analyzed with X-ray fluorescence spectroscopy. Biaxial flexural strength was measured using a piston-on-three-ball test. The surface fraction and penetration depth of the monoclinic phase were examined using X-ray diffraction and scanning electron microscopy, respectively. The tooth-colored 3Y-TZP specimens contained Fe2O3 and Er2O3 (infiltration technique), and Fe2O3 (powder mixing method) at concentrations of<0.5wt%. The tooth-colored 3Y-TZP had higher strength than the non-colored material after 100h of autoclaving. In terms of surface fraction and penetration depth, the generation of monoclinic phase was significantly lower in the tooth-colored 3Y-TZP than in the non-colored material. The tooth-colored 3Y-TZP possessed equivalent biaxial flexural strength to that of the non-colored material and higher resistance to LTD regardless of the coloring technique (infiltration technique or powder mixing method) when the coloring pigments were contained at concentrations used in the present study. © 2015 Elsevier Ltd.

  • 27.
    Reveron, Helen
    et al.
    Université de Lyon-INSA de Lyon, France.
    Fornabaio, Marta
    Politecnico di Torino, Italy.
    Palmero, Paolo
    Politecnico di Torino, Italy.
    Fürderer, Tobias
    DOCERAM, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF, Keramer.
    Lughi, Vanni
    University of Trieste,Italy.
    Bonifacio, Alois
    University of Trieste, Italy.
    Sergo, Valter
    University of Trieste, Italy.
    Montanaro, Laura
    Politecnico di Torino, Italy.
    Chevalier, Jerome
    Université de Lyon-INSA de Lyon, France.
    Towards long lasting zirconia-based composites for dental implants: Transformation induced plasticity and its consequence on ceramic reliability2017In: Acta Biomaterialia, ISSN 17427061, Vol. 48, p. 423-432Article in journal (Refereed)
    Abstract [en]

    Zirconia-based composites were developed through an innovative processing route able to tune compositional and microstructural features very precisely. Fully-dense ceria-stabilized zirconia ceramics (84 vol% Ce-TZP) containing equiaxed alumina (8 vol%Al2O3) and elongated strontium hexa-aluminate (8 vol% SrAl12O19) second phases were obtained by conventional sintering. This work deals with the effect of the zirconia stabilization degree (CeO2 in the range 10.0–11.5 mol%) on the transformability and mechanical properties of Ce-TZP-Al2O3-SrAl12O19 materials. Vickers hardness, biaxial flexural strength and Single-edge V-notched beam tests revealed a strong influence of ceria content on the mechanical properties. Composites with 11.0 mol% CeO2 or above exhibited the classical behaviour of brittle ceramics, with no apparent plasticity and very low strain to failure. On the contrary, composites with 10.5 mol% CeO2 or less showed large transformation-induced plasticity and almost no dispersion in strength data. Materials with 10.5 mol% of ceria showed the highest values in terms of biaxial bending strength (up to 1.1 GPa) and fracture toughness (>10 MPa√m). In these ceramics, as zirconia transformation precedes failure, the Weibull modulus was exceptionally high and reached a value of 60, which is in the range typically reported for metals. The results achieved demonstrate the high potential of using these new strong, tough and stable zirconia-based composites in structural biomedical applications. Statement of Significance Yttria-stabilized (Y-TZP) zirconia ceramics are increasingly used for developing metal-free restorations and dental implants. Despite their success related to their excellent mechanical resistance, Y-TZP can undergo Low Temperature Degradation which could be responsible for restoration damage or even worst the failure of the implant. Current research is focusing on strategies to improve the LTD resistance of Y-TZP or to develop alternative composites with better stability in vivo. In this work the mechanical characterization of a new type of very-stable zirconia-based composites is presented. These materials are composed of ceria-stabilized zirconia (84 vol%Ce-TZP) containing two second phases (α-alumina and strontium hexa-aluminate) and exhibit exceptional strength, toughness and ductility, which may allow the processing of dental implants with a perfect reliability and longer lifetime.

  • 28. Schienle, Stefanie
    et al.
    Al-Ahmad, Ali
    Kohal, Ralf Joachim
    Bernsmann, Falk
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Montanaro, Laura
    Palmero, Paola
    Fürderer, Tobias
    Chevalier, Jérôme
    Hellwig, Elmar
    Karygianni, Lamprini
    Microbial adhesion on novel yttria-stabilized tetragonal zirconia (Y-TZP) implant surfaces with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coatings2016In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, p. 1719-1732Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES:

    Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concomitant infection. The rationale of this study was to assess the initial adhesion on novel implant surfaces of Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans upon incubation.

    MATERIALS AND METHODS:

    The tested samples were 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) samples with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coating (A) and 3Y-TZP samples coated with ceria-stabilized zirconia-based (Ce-TZP) composite and a-C:H:N (B). Uncoated 3Y-TZP samples (C) and bovine enamel slabs (BES) served as controls. Once the surface was characterized, the adherent microorganisms were quantified by estimating the colony-forming units (CFUs). Microbial vitality was assessed by live/dead staining, and microbial-biomaterial surface topography was visualized by scanning electron microscopy (SEM).

    RESULTS:

    Overall, A and B presented the lowest CFU values for all microorganisms, while C sheltered significantly less E. faecalis, P. aeruginosa, and C. albicans than BES. Compared to the controls, B demonstrated the lowest vitality values for E. coli (54.12 %) and C. albicans (67.99 %). Interestingly, A (29.24 %) exhibited higher eradication rates for S. aureus than B (13.95 %).

    CONCLUSIONS:

    Within the limitations of this study, a-C:H:N-coated 3Y-TZP surfaces tended to harbor less initially adherent microorganisms and selectively interfered with their vitality.

    CLINICAL RELEVANCE:

    This could enable further investigation of the new multi-functional zirconia surfaces to confirm their favorable antimicrobial properties in vivo.

  • 29.
    Shen, Zhijian
    et al.
    Stockholm University, Sweden.
    Liu, Leifeng
    Stockholm University, Sweden.
    Xu, Xiqing
    Stockholm University, Sweden.
    Zhao, Jing
    Stockholm University, Sweden.
    Eriksson, Mirva
    Stockholm University, Sweden.
    Zhong, Yuan
    Stockholm University, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Liu, Yihong
    Peking University School and Hospital of Stomatology, China.
    Kocjan, Andraz
    Jozef Stefan Institute, Slovenia.
    Fractography of self-glazed zirconia with improved reliability2017In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, ISSN 09552219, Vol. 37, no 14, p. 4339-4345Article in journal (Refereed)
    Abstract [en]

    The fractography of a new grade of zirconia ceramics, known as self-glazed zirconia, was investigated. The as-sintered intact top surface was made with superior smoothness that mimicked the optical appearances of the natural teeth enamel. The beneath surface opposite to this was made hierarchically rough with microscopic pits of the size up to 60. μm together with grain-level roughness of about 2. μm. The three-point bending test of the samples made with the hierarchically rough surface being tensile one demonstrated an average bending strength of 1120. ±. 70. MPa and a Weibull modulus of as high as 18 ascribed to the improved structural homogeneity. Surface topography was found the main origins of crack initiation leading to fracture. The observed unusually predominant transgranular fracture mode of submicron-sized grains disclosed a possible toughening mechanism of disassembling of mesocrystalline grains that differs significantly from the commonly quoted phase transformation toughening of this category of ceramics.

  • 30.
    Spies, B. C.
    et al.
    University of Freiburg, Germany.
    Maass, M. E.
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Sergo, V.
    University of Trieste, Italy.
    Kiemle, T.
    University of Tuebingen, Germany.
    Berthold, C.
    University of Tuebingen, Germany.
    Gurian, E.
    University of Trieste, Italy.
    Fornasaro, S.
    University of Trieste, Italy.
    Vach, K.
    University of Freiburg, Germany.
    Kohal, R. -J
    University of Freiburg, Germany.
    Long-term stability of an injection-molded zirconia bone-level implant: A testing protocol considering aging kinetics and dynamic fatigue2017In: Dental Materials, ISSN 01095641, Vol. 33, no 8, p. 954-965Article in journal (Refereed)
    Abstract [en]

    Objective Separately addressing the fatigue resistance (ISO 14801, evaluation of final product) and aging behavior (ISO 13356, standardized sample) of oral implants made from yttria-stabilized zirconia proved to be insufficient in verifying their long-term stability, since (1) implant processing is known to significantly influence transformation kinetics and (2) aging, up from a certain level, is liable to decrease fatigue resistance. Therefore, the aim of this investigation was to apply a new testing protocol considering environmental conditions adequately inducing aging during dynamic fatigue. Methods Zirconia implants were dynamically loaded (107 cycles), hydrothermally aged (85°, 60 days) or subjected to both treatments simultaneously. Subsequent, monoclinic intensity ratios (Xm) were obtained by locally resolved X-ray microdiffraction (μ-XRD2). Transformation propagation was monitored at cross-sections by μ-Raman spectroscopy and scanning electron microscopy (SEM). Finally, implants were statically loaded to fracture. Linear regression models (fracture load) and mixed models (Xm) were used for statistical analyses. Results All treatments resulted in increased fracture load (p ≤ 0.005), indicating the formation of transformation induced compressive stresses around surface defects during all treatment modalities. However, only hydrothermal and combinational treatment were found to increase Xm (p < 0.001). No change in Xm was observed for solely dynamically loaded samples (p ≥ 0.524). Depending on the variable observed, a monoclinic layer thickness of 1–2 μm (SEM) or 6–8 μm (Raman spectroscopy) was measured at surfaces exposed to water during treatments. Significance Hydrothermal aging was successfully induced during dynamic fatigue. Therefore, the presented setup might serve as reference protocol for ensuring pre-clinically long-term reliability of zirconia oral implants.

  • 31.
    Spies, Benedikt C
    et al.
    University of Freiburg, Germany; Humboldt-Universität zu Berlin, Germany.
    Fross, Alexander
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Bagegni, Aimen
    University of Freiburg, Germany.
    Doerken, Sam
    University of Freiburg, Germany.
    Kohal, Ralf-Joachim
    University of Freiburg, Germany.
    Stability and aging resistance of a zirconia oral implant using a carbon fiber-reinforced screw for implant-abutment connection2018In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 34, no 10, p. 1585-1595Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To investigate the long-term stability of a metal-free zirconia two-piece implant assembled with a carbon fiber-reinforced (CRF) screw by means of transformation propagation, potential changes in surface roughness, the gap size of the implant-abutment connection, and fracture load values.

    METHODS: In a combined procedure, two-piece implants made from alumina-toughened zirconia were dynamically loaded (107 cycles) and hydrothermally aged (85°, 60days). Implants made from titanium (Ti) and a titanium-zirconium (TiZr) alloy with a titanium abutment screw served as control. Transformation propagation (ATZ) and gap size of the IAC were monitored at cross-sections by scanning electron microscopy (SEM). Furthermore, changes in surface roughness of ATZ implants were measured. Finally, implants were statically loaded to fracture. Linear regression models and pairwise comparisons were used for statistical analyses.

    RESULTS: Independent of the implant bulk material, dynamic loading/hydrothermal aging did not decrease fracture resistance (p=0.704). All test and control implants fractured at mean loads >1100N. Gap size of the IAC remained stable (<5μm) or decreased. None of the CFR screws fractured during static or dynamic loading. Monoclinic layer thickness of ATZ implants increased by 2-3μm at surfaces exposed to water, including internal surfaces of the IAC. No changes in surface roughness were observed.

    SIGNIFICANCE: Combined hydrothermal aging and dynamic loading did not affect the above-mentioned parameters of the evaluated two-piece ATZ implant. Mean fracture loads >1100N suggest a reliable clinical application.

  • 32.
    Svensson, T.
    et al.
    European Laboratory for Non-linear Spectroscopy (LENS).
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Burresi, M.
    European Laboratory for Non-linear Spectroscopy (LENS).
    Savo, R.
    European Laboratory for Non-linear Spectroscopy (LENS).
    Xu, C.T.
    Lund University.
    Wiersma, D.S.
    European Laboratory for Non-linear Spectroscopy (LENS).
    Svanberg, S.
    Lund University.
    Pore size assessment based on wall collision broadening of spectral lines of confined gas: Experiments on strongly scattering nanoporous ceramics with fine-tuned pore sizes2013In: Applied Physics B: Lasers and Optics, 2013, Vol. 110, no 2, p. 147-154Conference paper (Refereed)
    Abstract [en]

    Wall collision broadening of absorption lines of gases confined in porous media is a recently opened domain of high-resolution spectroscopy. Here, we present an experimental investigation of its application for pore size assessment. We report on the manufacturing of nanoporous zirconia ceramics with well-defined pore sizes fine-tuned from 50 to 150 nm. The resulting pore structure is characterized using mercury intrusion porosimetry, and the optical properties of these strongly scattering materials are measured using femtosecond photon time-of-flight spectroscopy (transport mean free paths found to be tuned from 2.3 to 1.2 μm as the pore size increase). Wall collision line broadening is studied by performing near-infrared (760 nm) high-resolution diode laser spectroscopy of confined oxygen molecules. A simple method for quantitative estimation of the pore size is outlined and shown to produce results in agreement with mercury intrusion porosimetry. At the same time, the need for improved understanding of wall collision broadening is emphasized. © 2012 Springer-Verlag.

  • 33.
    Svensson, T.
    et al.
    Lund University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Lewander, M.
    Lund University.
    Xu, C.T.
    Lund University.
    Svanberg, S.
    Lund University.
    Disordered, strongly scattering porous materials as miniature multipass gas cells2011In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, no 14Article in journal (Refereed)
    Abstract [en]

    We investigate the interaction of light and gas in strongly scattering nano- and macroporous media. Manufacturing and structural characterization of ZrO2, Al2O3 and TiO2 ceramics with different pore sizes, measurements of optical properties using photon time-of-flight spectroscopy, and high-resolution laser spectroscopy of O 2 at 760 nm are reported. We show that extreme light scattering can be utilized to realize miniature spectroscopic gas cells. Path length enhancement factors up to 750 are reached (5.4 m path through gas for light transmitted through a 7 mm ZrO2 with 49% porosity and 115 nm pores). © 2011 American Physical Society.

  • 34.
    Svensson, T.
    et al.
    University of Florence.
    Vynck, K.
    University of Florence.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Farina, A.
    Istituto di Fotonica e Nanotecnologie (IFN-CNR).
    Pifferi, A.
    Istituto di Fotonica e Nanotecnologie (IFN-CNR).
    Wiersma, D.S.
    University of Florence.
    Light diffusion in quenched disorder: Role of step correlations2014In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 89, no 2Article in journal (Refereed)
    Abstract [en]

    We present a theoretical and experimental study of light transport in disordered media with strongly heterogeneous distribution of scatterers formed via nonscattering regions. Step correlations induced by quenched disorder are found to prevent diffusivity from diverging with increasing heterogeneity scale, contrary to expectations from annealed models. Spectral diffusivity is measured for a porous ceramic where nanopores act as scatterers and macropores render their distribution heterogeneous. Results agree well with Monte Carlo simulations and a proposed analytical model. © 2014 American Physical Society.

  • 35.
    Tönnäng, Lenny
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Malmström, J.
    Oral and Maxillofacial Unit Halmstad.
    Abrahamsson, P.
    Oral and Maxillofacial Unit Halmstad.
    3D printed versus machined zirconia for dental applications2015Conference paper (Other academic)
  • 36.
    Venturini, F.
    et al.
    Zurich University of Applied Sciences, Switzerland.
    Schonherr, V.
    Zurich University of Applied Sciences, Switzerland.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Ultracompact oxygen sensor using nanoporous materials as strongly scattering multipass cell for tunable diode laser absorption spectroscopy2017In: Optics InfoBase Conference Papers, 2017Conference paper (Refereed)
    Abstract [en]

    In this work, a variety of disordered strongly-scattering nanoporous ceramic materials was systematically investigated to study the influence of the material and processing parameters on their performance. To use these materials as miniature multipass cell it is necessary to achieve the highest possible optical absorption path length (OPL). On the other hand, an increased mean OPL is associated with an increased scattering. This negatively impacts on the signal obtained from the photodiode due to the increase in the solid angle of the transmitted light and to the consequently lower collected light intensity. For practical purposes, therefore, the choice of the optimal material should be a compromise between these two aspects. The material with most promising properties proved to be ZrO2 with porosity from 50% to 55%. With samples of 6 mm thickness it is possible to realize mean OPL above 6 m.

  • 37.
    Venturini, F
    et al.
    Zurich University of Applied Sciences, Switzerland.
    Schönherr, V
    Zurich University of Applied Sciences, Switzerland.
    Rey, J. M.
    Zurich University of Applied Sciences, Switzerland.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF, Keramer.
    Characterization of strongly scattering nanoporous materials as miniaturized multipass cell for tunable diode laser absorption spectroscopy2017In: Applied Physics B: Lasers and Optics, ISSN 09462171, Vol. 123, no 4, article id 136Article in journal (Refereed)
    Abstract [en]

    Through the confinement of gas in nanoporous materials, it is possible to significantly increase the path length for light–gas interaction. This enables the observation of much stronger absorption features for the confined gas molecules. In this work, we systematically characterized a variety of disordered strongly scattering ZrO2 and Al2O3 nanoporous ceramic materials to exploit the potential of gas in scattering media absorption spectroscopy. As a result, we identified a material with an unprecedented performance in terms of optical path length enhancement. In ZrO2 with thicknesses above 6 mm, the path enhancement exceeds 1000. The results obtained with near-infrared absorption spectroscopy on oxygen were validated by time-of-flight measurements at 700 nm, thus demonstrating their robustness. Finally, we report quantitative oxygen concentration measurement using nanoporous materials as miniaturized random-scattering multipass cell with an extremely simple and low-cost setup.

  • 38.
    Xu, C.T.
    et al.
    Lund University.
    Lewander, M.
    Lund University.
    Andersson-Engels, S.
    Lund University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Svensson, T.
    Lund University.
    Svanberg, S.
    Lund University.
    Wall-collision line broadening of molecular oxygen within nanoporous materials2011In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 84, no 4Article in journal (Refereed)
    Abstract [en]

    Wall-collision broadening of near-infrared absorption lines of molecular oxygen confined in nanoporous zirconia is studied by employing high-resolution diode-laser spectroscopy. The broadening is studied for pores of different sizes under a range of pressures, providing new insights on how wall collisions and intermolecular collisions influence the total spectroscopic line profile. The pressure series show that wall-collision broadening is relatively more prominent under reduced pressures, enabling sensitive means to probe pore sizes of porous materials. In addition, we show that the total wall-collision-broadened profile strongly deviates from a Voigt profile and that wall-collision broadening exhibits an additive-like behavior to the pressure and Doppler broadening. © 2011 American Physical Society.

1 - 38 of 38
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.5