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  • 1.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF, Keramer.
    Zirconia in applications with bone contact2016Konferansepaper (Annet vitenskapelig)
  • 2.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Lyckfeldt, Ola
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Johansson, Emil
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Visible-Light Curable Ceramic Suspensions for Additive Manufacturing of Dense Ceramic Parts2016Konferansepaper (Annet vitenskapelig)
  • 3.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Shen, James Zhijian
    Stockholm University, Sweden.
    Defect Minimization in Prosthetic Ceramics2014Inngår i: Advanced Ceramics for Dentistry, Elsevier Inc. , 2014, s. 359-373Kapittel i bok, del av antologi (Fagfellevurdert)
    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.

  • 4.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Shen, James Zhijian
    Stockholm University, Sweden.
    Effects of granule density on strength and granule related defects in zirconia2012Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, nr 11, s. 2653-2659Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 5.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Tönnäng, Lenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    The effect of softmachining parameters on the mechanical strength of zirconia2015Konferansepaper (Annet vitenskapelig)
  • 6.
    Adolfsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Venturini, Francesca
    ZHAW School of Engineering, Switzerland.
    Schönherr, Veit
    ZHAW School of Engineering, Switzerland .
    Rey, Julien
    ZHAW School of Engineering, Switzerland .
    Characterization oflight-gas interaction in strongly-scattering nanoporous materials and itsimplications for tunable diode laser absorption spectroscopy2016Inngår i: Applied Physics B: Lasers and Optics, 2016, Vol. 123, s. 123-136Konferansepaper (Annet vitenskapelig)
    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.

  • 7.
    Akbari, Saeed
    et al.
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Kostov, Konstantin Stoychev
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Brinkfeldt, Klas
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Lim, Jang-Kwon
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Andersson, Dag
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Bakowski, Mietek
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Wang, Qin
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Salter, Michael
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Ceramic Additive Manufacturing Potential for Power Electronics Packaging2022Inngår i: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 12, nr 11, s. 1857-1866Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Compared with silicon-based power devices, wide band gap (WBG) semiconductor devices operate at significantly higher power densities required in applications such as electric vehicles and more electric airplanes. This necessitates development of power electronics packages with enhanced thermal characteristics that fulfil the electrical insulation requirements. The present research investigates the feasibility of using ceramic additive manufacturing (AM), also known as three-dimensional (3D) printing, to address thermal and electrical requirements in packaging gallium nitride (GaN) based high-electron-mobility transistors (HEMTs). The goal is to exploit design freedom and manufacturing flexibility provided by ceramic AM to fabricate power device packages with a lower junction-to-ambient thermal resistance (<italic>R</italic>&#x03B8;JA). Ceramic AM also enables incorporation of intricate 3D features into the package structure in order to control the isolation distance between the package source and drain contact pads. Moreover, AM allows to fabricate different parts of the packaging assembly as a single structure to avoid high thermal resistance interfaces. For example, the ceramic package and the ceramic heatsink can be printed as a single part without any bonding layer. Thermal simulations under different thermal loading and cooling conditions show the improvement of thermal performance of the package fabricated by ceramic AM. If assisted by an efficient cooling strategy, the proposed package has the potential to reduce <italic>R</italic>&#x03B8;JA by up to 48%. The results of the preliminary efforts to fabricate the ceramic package by AM are presented, and the challenges that have to be overcome for further development of this manufacturing method are recognized and discussed. 

  • 8.
    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, Material och produktion, 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 Materials2017Inngår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 27, nr 40, artikkel-id 1702512Artikkel i tidsskrift (Fagfellevurdert)
    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. 

  • 9.
    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, Material och produktion, 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 materials2017Inngår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 33, nr 2, s. 241-255Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10.
    Anderud, Jonas
    et al.
    Malmö University, Sweden; Region Halland, Sweden.
    Abrahamsson, Peter
    Region Halland, Sweden.
    Jimbo, Ryo
    Malmö University, Sweden.
    Isaksson, Sten
    Region Halland, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Malmström, Johan
    Region Halland, Sweden.
    Naito, Yoshihito
    University of Tokushima, Japan.
    Wennerberg, Ann
    Malmö University, Sweden.
    Guided bone augmentation using ceramic space-maintaining devices: The impact of chemistry2015Inngår i: Clinical, Cosmetic and Investigational Dentistry, E-ISSN 1179-1357, Vol. 7, s. 45-53Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11.
    Anderud, Jonas
    et al.
    Malmö University, Sweden; Region Halland, Sweden.
    Jimbo, Ryo
    Malmö University, Sweden.
    Abrahamsson, Peter
    Region Halland, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Malmström, Johan
    Region Halland, Sweden.
    Wennerberg, Ann
    Malmö University, Sweden.
    The impact of surface roughness and permeability in hydroxyapatite bone regeneration membranes2015Inngår i: Clinical Oral Implants Research, ISSN 0905-7161, E-ISSN 1600-0501, Vol. 27, nr 8, s. 1047-1054Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12.
    Brinkfeldt, Klas
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Amen, Rafael
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Tegehall, Per-Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Johander, Per
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Andersson, Dag
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Thermo-mechanical simulations and measurements on high temperature interconnections2011Inngår i: 12th Int. Conf. on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2011, 2011, artikkel-id 5765772Konferansepaper (Fagfellevurdert)
    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.

  • 13.
    Brinkfeldt, Klas
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Formánek, J.
    Czech Technical University.
    Laposa, A.
    Czech Technical University.
    Jakovenko, J.
    Czech Technical University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Johander, Per
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Simulations of a high temperature pressure sensor packaging and interconnection2012Inngår i: EuroSimE 2012: 13th International Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, 2012Konferansepaper (Fagfellevurdert)
    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.

  • 14.
    Burkhardt, Felix
    et al.
    University of Freiburg, Germany.
    Harlass, Markus
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Vach, Kirstin
    University of Freiburg, Germany.
    Spies, Benedikt
    University of Freiburg, Germany.
    Kohal, Ralf-Joachim
    University of Freiburg, Germany.
    A novel zirconia-based composite presents an aging resistant material for narrow-diameter ceramic implants2021Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 14, nr 9, artikkel-id 2151Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel ceria-stabilized zirconia-alumina-aluminate composite (Ce-TZP-comp) that is not prone to aging presents a potential alternative to yttrium-stabilized zirconia for ceramic oral implants. The objective of this study was to evaluate the long-term stability of a one-piece narrow-diameter implant made of Ce-TZP-comp. Implant prototypes with a narrow (3.4 mm) and regular (4.0 mm) diameter were embedded according to ISO 14801, and subgroups (n = 8) were subsequently exposed to dynamic loading (107 cycles, 98N) and/or hydrothermal treatment (aging, 85◦C). Loading/aging was only applied as a combined protocol for the 4.0 mm diameter implants. One subgroup of each diameter remained untreated. One sample was cross-sectioned from each subgroup and evaluated with a scanning electron microscope for phase-transformation of the lattice. Finally, the remaining samples were loaded to fracture. A multivariate linear regression model was applied for statistical analyses (significance at p &lt; 0.05). All samples withstood the different loading/aging protocols and no transformation propagation was observed. The narrow diameter implants showed the lowest fracture load after combined loading/aging (628 ± 56 N; p &lt; 0.01), whereas all other subgroups exhibited no significantly reduced fracture resistance (between 762 ± 62 and 806 ± 73 N; p &lt; 0.05). Therefore, fracture load values of Ce-TZP-comp implants suggest a reliable intraoral clinical application in the anterior jaw regions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • 15.
    Burkhardt, Felix
    et al.
    University of Freiburg, Germany; Lennart Riemer Zahnarztpraxis Franzem, Germany.
    Spies, Benedikt
    University of Freiburg, Germany; Lennart Riemer Zahnarztpraxis Franzem, Germany.
    Riemer, Lennart
    University of Freiburg, Germany; Lennart Riemer Zahnarztpraxis Franzem, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Doerken, Sam
    University of Freiburg, Germany.
    Kohal, Ralf J.
    University of Freiburg, Germany; Lennart Riemer Zahnarztpraxis Franzem, Germany.
    Fracture resistance and crystal phase transformation of a one- and a two-piece zirconia implant with and without simultaneous loading and aging—An in vitro study2021Inngår i: Clinical Oral Implants Research, ISSN 0905-7161, E-ISSN 1600-0501, Vol. 32, nr 11, s. 1288-1298Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: To evaluate the influence of artificial aging on the transformation propagation and fracture resistance of zirconia implants. Methods: One-piece (with integrated implant abutment, 1P; regular diameter [4.1mm]; n = 16) and two-piece (with separate implant abutment, 2P; wide diameter [5 mm]; n = 16) zirconia implants were embedded according to ISO 14801. A two-piece titanium–zirconium implant (Ti-Zr; 4.1 mm diameter) served as a control (n = 16). One subgroup (n = 8) of each system was simultaneously dynamically loaded (107 cycles; 98N) and hydrothermally aged (85°C, 58 days), while the other subgroup (n = 8) remained untreated. Finally, specimens were statically loaded to fracture. Potential crystal phase transformation was examined at cross sections using scanning electron microscopy (SEM). A multivariate linear regression model was applied for statistical analyses. Results: The fracture resistance of 1P (1,117 [SD = 38] N; loaded/aged: 1,009 [60] N), 2P (850 [36] N; loaded/aged: 799 [84] N), and Ti-Zr implants (1,338 [205] N; loaded/aged: 1,319 [247] N) was not affected significantly by loading/aging (p =.171). However, when comparing the systems, they revealed significant differences independent of loading/aging (p ≤.001). Regarding the crystal structure, a transformation zone was observed in SEM images of 1P only after aging, while 2P showed a transformation zone even before aging. After hydrothermal treatment, an increase of this monoclinic layer was observed in both systems. Conclusions: The Ti-Zr control implant showed higher fracture resistance compared to both zirconia implants. Loading/aging had no significant impact on the fracture resistance of both zirconia implants. The wide-body 2P zirconia implant was weaker than the regular body 1P implant. © 2021 The Authors. 

  • 16.
    Dehestani, Mahdi
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF. Novo Nordisk A/S, Denmark.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Phase stability and mechanical properties of zirconia and zirconia composites2013Inngår i: International Journal of Applied Ceramic Technology, ISSN 1546542X, Vol. 10, nr 1, s. 129-141Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 17.
    Dehestani, Mahdi
    et al.
    Purdue University, US.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Stanciu, Lia A.
    Purdue University, US.
    Mechanical properties and corrosion behavior of powder metallurgy iron-hydroxyapatite composites for biodegradable implant applications2016Inngår i: Materials and Design, ISSN 0264-1275, Vol. 109, s. 556-569Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 18.
    Dehestani, Mahdi
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Ilver, L.
    Chalmers University of Technology.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Enhancing the bioactivity of zirconia and zirconia composites by surface modification2012Inngår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 100 B, nr 3, s. 832-840Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 19.
    Dehestani, Mahdi
    et al.
    Purdue University, USA.
    Zemlyanov, Dmitry Yu
    Purdue University, USA.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Stanciu, Lia A.
    Purdue University, USA.
    Improving bioactivity of inert bioceramics by a novel Mg-incorporated solution treatment2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 425, s. 564-575Artikkel i tidsskrift (Fagfellevurdert)
    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. 

  • 20.
    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, Material och produktion, 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 concepts2017Inngår i: Advances in Ceramic Biomaterials: Materials, Devices and Challenges / [ed] Palmero, P., Cambier, F., De Barra, E., Elsevier Inc. , 2017, 1, s. 355-389Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 21.
    Fäldt, J.
    et al.
    Nobel Biocare AB.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Future use of ceramics in dentistry2008Inngår i: 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, 2008Konferansepaper (Fagfellevurdert)
    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.

  • 22. Grandfield, K.
    et al.
    Palmquist, A.
    Ericson, F.
    Malmström, J.
    Emanuelsson, L.
    Slotte, C.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, 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 Maxilla2012Inngår i: Clinical Implant Dentistry and Related Research, ISSN 15230899, Vol. 14, nr 3, s. 461-469Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 23.
    Guo, Zengwei
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Tam, Pui
    Chalmers University of Technology, Sweden.
    Nanostructured micro particles as a low-cost and sustainable catalyst in the recycling of PET fiber waste by the glycolysis method2021Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 126, s. 559-566Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Magnetic Mg-Al-O@Fe3O4 micro particles were synthesized by coating nanosized Mg-Al double oxides onto Fe3O4 micro particles. The formed hierarchical structure gave Mg-Al-O@Fe3O4 micro particles a high active surface area, which enabled these micro particles to work efficiently as a catalyst in the glycolysis of poly(ethylene terephthalate) (PET). The bis(hydroxyethyl) terephthalate (BHET) yield reached above 80 mol% in the presence of 0.5 wt% of Mg-Al-O@Fe3O4 micro catalyst in the reaction system within 90 min at 240 °C. After the reaction, Mg-Al-O@Fe3O4 micro catalyst was easily retrieved by a magnetic decantation and can be repetitively used for two times with a high catalytic efficiency. After that, the deactivated Mg-Al-O@Fe3O4 micro catalyst can be regenerated by heat treatment. The regenerated Mg-Al-O@Fe3O4 micro catalyst displays a comparable catalytic performance as that of the virgin catalyst. In addition, the Mg-Al double oxides and Fe3O4 micro particles are low-cost and environmentally benign. Therefore, the Mg-Al-O@Fe3O4 micro catalyst may contribute to an economically and environmentally improved large-scale circular recycling of PET fiber waste. © 2021 The Author(s)

  • 24.
    Guo, Zingwei
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Eriksson, Mikael
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    de la Motte, Hanna
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Circular recycling of polyester textile waste using a sustainable catalyst2021Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 283, artikkel-id 124579Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A tremendous amount of polyester textile waste is discarded every year, which has caused a serious problem for the environment. In this study, the feasibility of circular recycling of polyester textile waste is investigated through a glycolysis process in the presence of environmentally friendly Mg–Al double oxides pellets as catalyst. Even though the catalytic performance of Mg–Al double oxides pellets is slightly lower than their granules at 240 °C, pellets were used as they benefit from a good recyclability. The pellet catalysts could be cycled three times without losing structural integrity or catalytic activity in the glycolysis of (poly(ethylene terephthalate)(PET)). However, to restore the catalytic activity after three cycles, the catalyst was regenerated through a heat treatment after the glycolysis reaction. After that the catalyst showed a comparable catalytic activity as that of virgin catalyst. In the glycolysis process, the monomer bis(hydroxyethyl) terephthalate (BHET) is generated and recovered. The molar yield of BHET was in the reaction over 80 mol%. From the recovered BHET, regenerated PET (r-PET) with an intrinsic viscosity (IV) of 0.67 was synthesized. The r-PET showed a very good spinnability in the melt spinning test. The quality of the obtained r-PET fibers was comparable to virgin PET fibers. 

  • 25.
    Johansson, Emil
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Lidström, Oscar
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Lyckfeldt, Ola
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Jan, Johansson
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Influence of Resin Composition on the Defect Formation in Alumina Manufactured by Stereolithography2017Inngår i: Materials, E-ISSN 1996-1944, Vol. 10, nr 2, artikkel-id 138Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    materials-10-00138.pdf
  • 26.
    Johansson, Lars Åke
    et al.
    University of Gothenburg, Sweden.
    Isaksson, Sten G.
    Malmö University, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Lindh, Christina
    Malmö University, Sweden.
    Sennerby, Lars
    University of Gothenburg, Sweden.
    Bone Regeneration Using a Hollow Hydroxyapatite Space-Maintaining Device for Maxillary Sinus Floor Augmentation - A Clinical Pilot Study2012Inngår i: Clinical Implant Dentistry and Related Research, ISSN 1523-0899, E-ISSN 1708-8208, Vol. 14, nr 4, s. 575-584Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 27.
    Karygianni, Lamprini
    et al.
    University of Freiburg, Germany.
    Jähnig, Andrea
    University of Freiburg, Germany.
    Schienle, Stefanie
    University of Freiburg, Germany.
    Bernsmann, Falk
    NTTF Coatings GmbH, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Kohal, Ralf Joachim
    University of Freiburg, Germany.
    Chevalier, Jerome
    University of Lyon, France.
    Hellwig, Elmar
    University of Freiburg, Germany.
    Al-Ahmad, Ali
    University of Freiburg, Germany.
    Initial bacterial adhesion on different yttria-stabilized tetragonal zirconia implant surfaces in vitro2013Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 6, nr 12, s. 5659-5674Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 28.
    Kohal, Ralf-Joachim
    et al.
    University of Freiburg, Germany.
    Schikofski, Tim
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Vach, Kirstin
    University of Freiburg, Germany.
    Patzelt, Sebastian Berthold Maximilian
    University of Freiburg, Germany; Private Dental Clinic Zimmern ob Rottweil, Germany.
    Nold, Julian
    University of Freiburg, Germany.
    Wemken, Gregor
    University of Freiburg, Germany.
    Fracture Resistance of a Two-Piece Zirconia Implant System after Artificial Loading and/or Hydrothermal Aging—An In Vitro Investigation2023Inngår i: Journal of Functional Biomaterials, ISSN 2079-4983, E-ISSN 2079-4983, Vol. 14, nr 12, artikkel-id 567Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the present study was to assess the fracture resistance of a two-piece alumina-toughened zirconia implant system with a carbon-reinforced PEEK abutment screw. Methods: Thirty-two implants with screw-retained zirconia abutments were divided into four groups of eight samples each. Group 0 (control group) was neither loaded nor aged in a chewing simulator; group H was hydrothermally aged; group L was loaded with 98 N; and group HL was subjected to both hydrothermal aging and loading in a chewing simulator. One sample of each group was evaluated for t-m phase transformation, and the others were loaded until fracture. A one-way ANOVA was applied to evaluate differences between the groups. Results: No implant fracture occurred during the artificial chewing simulation. Furthermore, there were no statistically significant differences (p > 0.05) between the groups in terms of fracture resistance (group 0: 783 ± 43 N; group H: 742 ± 43 N; group L: 757 ± 86 N; group HL: 740 ± 43 N) and bending moment (group 0: 433 ± 26 Ncm; group H: 413 ± 23 Ncm; group L: 422 ± 49 Ncm; group HL: 408 ± 27 Ncm). Conclusions: Within the limitations of the present investigation, it can be concluded that artificial loading and hydrothermal aging do not reduce the fracture resistance of the investigated implant system. 

  • 29.
    Kohal, R-J
    et al.
    University of Freiburg, Germany.
    von Schierholz, C
    University of Freiburg, Germany.
    Nold, J
    University of Freiburg, Germany.
    Spies, BC
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Vach, K
    University of Freiburg, Germany.
    Burkhardt, F
    University of Freiburg, Germany.
    Influence of loading and aging on the fracture strength of an injection-molded two-piece zirconia implant restored with a zirconia abutment2023Inngår i: Clinical Oral Implants Research, ISSN 0905-7161, E-ISSN 1600-0501, Vol. 34, nr 2, s. 105-115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: To investigate the fracture strength and potential phase transformation of an injection-molded two-piece zirconia implant restored with a zirconia abutment after loading and/or aging. Methods: Thirty-two two-piece zirconia implants (4.0 mm diameter) restored with zirconia abutments were embedded according to ISO 14801 and divided into four groups (n = 8/group): Three groups were either exclusively hydrothermally treated (group HT; 85°C), dynamically loaded (group DL; 107 cycles; 98 N), or subjected to both treatments simultaneously (group DL/HT). One group remained untreated (group 0). A sample from each group was cross-sectioned and examined by scanning electron microscopy for possible crystal phase transformation. The remaining samples were then loaded to fracture in a static loading test. A one-way ANOVA was used for statistical analyses. Results: During dynamic loading, three implants of group DL and six implants of group DL/HT fractured at a load of 98 N. The fracture strength of group DL/HT (108 ± 141 Ncm) was significantly reduced compared to the other groups (group 0: 342 ± 36 Ncm; HT: 363 ± 49 Ncm; DL: 264 ± 198 Ncm) (p &lt;.05). Fractures from group 0 and HT occurred at both implant and abutment level, whereas implants from group DL and DL/HT fractured only at implant level. A shallow monoclinic transformation zone of approximately 2 μm was observed following hydrothermal treatment. Conclusions: Within the limitations of this study, it can be concluded that dynamic loading and the combination of loading and aging reduced the fracture strength of the implant abutment combination. Hydrothermal treatment caused a shallow transformation zone which had no influence on the fracture strength. © 2022 The Authors. 

  • 30.
    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, Material och produktion, IVF.
    Shen, Zhijian
    Stockholm University, Sweden.
    Dense and strong ZrO2 ceramics fully densified in <15 min2019Inngår i: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 118, nr 1-2, s. 23-29Artikkel i tidsskrift (Fagfellevurdert)
    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. 

    Fulltekst (pdf)
    fulltext
  • 31.
    Liens, Alethea
    et al.
    Université de Lyon, France; ANTHOGYR, France.
    Reveron, Helen
    Université de Lyon, France.
    Douillard, Thierry
    Université de Lyon, France.
    Blanchard, Nicholas
    Université de Lyon, France.
    Lughi, Vanni
    University of Trieste, Italy.
    Sergo, Valter
    University of Trieste, Italy; University of Macau, China.
    Laquai, Rene
    BAM Bundesanstalt für Materialforschung und -Prüfung, Germany.
    Müller, Bernd
    BAM Bundesanstalt für Materialforschung und -Prüfung, Germany.
    Bruno, Giovanni
    BAM Bundesanstalt für Materialforschung und -Prüfung, Germany.
    Schomer, Sven
    MOESCHTER GROUP Holding GmbH, Germany.
    Fürderer, Tobias
    MOESCHTER GROUP Holding GmbH, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Courtois, Nicolas
    ANTHOGYR, France.
    Swain, Michael
    University of Sydney, Australia; Don State Technical University, Russia.
    Chevalier, Jerome
    Université de Lyon, France.
    Phase transformation induces plasticity with negligible damage in ceria-stabilized zirconia-based ceramics2020Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 183, s. 261-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ceramics and their composites are in general brittle materials because they are predominantly made up of ionic and covalent bonds that avoid dislocation motion at room temperature. However, a remarkable ductile behavior has been observed on newly developed 11 mol.% ceria-stabilized zirconia (11Ce-TZP) composite containing fine alumina (8 vol.% Al2O3) and elongated strontium hexa-aluminate (8 vol.% SrAl12O19) grains. The as-synthesized composite also has shown full resistance to Low Temperature Degradation (LTD), relatively high strength and exceptionally high Weibull modulus, allowing its use in a broader range of biomedical applications. In this study, to deepen the understanding of plastic deformation in Ce-TZP based composites that could soon be used for manufacturing dental implants, different mechanical tests were applied on the material, followed by complete microstructural characterization. Distinct from pure Ce-TZP material or other zirconia-based ceramics developed in the past, the material here studied can be permanently strained without affecting the Young modulus, indicating that the ductile response of tested samples cannot be associated to damage occurrence. This ductility is related to the stress-induced tetragonal to monoclinic (t-m) zirconia phase transformation, analogue to Transformation-Induced Plasticity (TRIP) steels, where retained austenite is transformed to martensite. The aim of this study is to corroborate if the observed plasticity can be associated exclusively to the zirconia t-m phase transformation, or also to microcraking induced by the transformation. The t-m transformed-zones produced after bending and biaxial tests were examined by X-ray refraction and SEM/TEM coupled with Raman. The results revealed that the observed elastic-plastic behavior occurs without extensive microcracking, confirming a purely elastic-plastic behavior driven by the phase transformation (absence of damage).

  • 32.
    Liu, Yan
    et al.
    Simtec Soft Sweden AB, Sweden.
    Adolfsson, Erik
    RISE Research Institutes of Sweden.
    Christoffersson, Örjan
    TurnTime Technologies AB, Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser. TurnTime Technologies AB, Sweden.
    Yan, Zhenghua
    Simtec Soft Sweden AB, Sweden.
    Simulation and Additive Manufacturing of Complexly Designed Aircraft Component2023Inngår i: Euro PM2023 Proceedings, European Powder Metallurgy Association (EPMA) , 2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An innovative component used for the cargo handling systems of Boeing 737 aircraft is developed to improve loaders’ working conditions and protect cargo spaces, passenger luggage, and goods from damage. Since the design of the component makes it difficult to manufacture using conventional techniques, metal Binder Jetting, an Additive Manufacturing technique both faster and more cost-effective compared to the conventional laser/electron beam techniques, is used. However, there is a risk of thermally induced distortion in connection with the post-processing, specifically the sintering step. To address this, a 3D computational fluid dynamics simulation model is developed and simulations are made to identify where and when unwanted distortions may occur during the sintering process. In the simulation, the sintering process follows about 15 hours full sintering cycle with all the heating, holding and cooling stages. The simulations are compared with experiments to validate the numerical results. 

  • 33.
    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, Material och produktion, IVF.
    Guided bone regeneration using individualized ceramic sheets2016Inngår i: International Journal of Oral and Maxillofacial Surgery, ISSN 0901-5027, E-ISSN 1399-0020, Vol. 45, nr 10, s. 1246-1252Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 34.
    Nakamura, K.
    et al.
    Tohoku University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, 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 ceramics2012Inngår i: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 120, nr 3, s. 249-254Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 35.
    Nakamura, K.
    et al.
    University of Gothenburg, Sweden; Tohoku University, Japan.
    Harada, A.
    Tohoku University, Japan.
    Ono, M.
    Japan Fine Ceramics Co. Ltd, Japan.
    Shibasaki, H.
    Japan Fine Ceramics Co. Ltd, Japan.
    Kanno, T.
    Tohoku University, Japan.
    Niwano, Y.
    Tohoku University, Japan.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Milleding, P.
    University of Gothenburg, Sweden.
    Örtengren, U.
    University of Gothenburg, Sweden; UiT The Arctic University of Norway, Norway.
    Effect of low-temperature degradation on the mechanical and microstructural properties of tooth-colored 3Y-TZP ceramics2016Inngår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 53, s. 301-311Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 36.
    Preiss, L.
    et al.
    Univ Lyon, France.
    Chopard-Lallier, A. -L
    Anthogyr SAS, France.
    Reveron, H.
    Univ Lyon, France.
    Bruyère-Garnier, K.
    Univ Lyon, France.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Kohal, R. -J
    University of Freiburg, Germany.
    Chevalier, J.
    Univ Lyon, France.
    Courtois, N.
    Anthogyr SAS, France.
    Bone healing, tissue effects and biomechanical fixation of ‘smooth’ ceramic-coated zirconia-based dental implants: An in vivo study in sheep2024Inngår i: Open Ceramics, ISSN 2666-5395, Vol. 17, artikkel-id 100528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, the effect of coating a zirconia-based ceramic oral implant with a material of the same composition to build a relatively smooth surface with three different porosity features was evaluated in vivo, at 4 and 8 weeks after implantation in sheep femoral condyles. The results showed that at 4 weeks, the three coated zirconia-based implants with smoother surface topographies behaved similarly and promoted faster bone healing compared to the results obtained in the same zirconia- or titanium-based implants, but with rougher sandblasted and acid-etched surfaces. In addition, higher pull-out strengths were estimated in the coated-ceramic sample compared to titanium sandblasted and etched one. The present work showed that zirconia coatings with smoother surfaces than those conventionally used in the market improved the early phase of bone healing, paving the way for shorter treatment times and improved patient outcomes. 

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  • 37.
    Rabel, Kerstin
    et al.
    University of Freiburg, Germany.
    Kohal, Ralf Joachim
    University of Freiburg, Germany.
    Steinberg, Thorsten
    University of Freiburg, Germany.
    Rolauffs, Bernd
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Altmann, Brigitte
    University of Freiburg, Germany.
    Human osteoblast and fibroblast response to oral implant biomaterials functionalized with non-thermal oxygen plasma2021Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 11, nr 1, artikkel-id 17302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plasma-treatment of oral implant biomaterials prior to clinical insertion is envisaged as a potential surface modification method for enhanced implant healing. To investigate a putative effect of plasma-functionalized implant biomaterials on oral tissue cells, this investigation examined the response of alveolar bone osteoblasts and gingival fibroblasts to clinically established zirconia- and titanium-based implant surfaces for bone and soft tissue integration. The biomaterials were either functionalized with oxygen-plasma in a plasma-cleaner or left untreated as controls, and were characterized in terms of topography and wettability. For the biological evaluation, the cell adhesion, morphogenesis, metabolic activity and proliferation were examined, since these parameters are closely interconnected during cell-biomaterial interaction. The results revealed that plasma-functionalization increased implant surface wettability. The magnitude of this effect thereby depended on surface topography parameters and initial wettability of the biomaterials. Concerning the cell response, plasma-functionalization of smooth surfaces affected initial fibroblast morphogenesis, whereas osteoblast morphology on rough surfaces was mainly influenced by topography. The plasma- and topography-induced differential cell morphologies were however not strong enough to trigger a change in proliferation behaviour. Hence, the results indicate that oxygen plasma-functionalization represents a possible cytocompatible implant surface modification method which can be applied for tailoring implant surface wettability. © 2021, The Author(s).

  • 38.
    Rabel, Kerstin
    et al.
    University of Freiburg, Germany.
    Kohal, ralf
    University of Freiburg, Germany.
    Steinberg, Thorsten
    University of Freiburg, Germany.
    Tomakidi, Pascal
    University of Freiburg, Germany.
    Rolauffs, Bernd
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Palmero, Paola
    Politecnico Di Torino, Italy.
    Fürderer, Tobias
    MOESCHTER GROUP Holding GmbH, Germany.
    Altmann, Brigitte
    University of Freiburg, Germany; .
    Controlling osteoblast morphology and proliferation via surface micro-topographies of implant biomaterials2020Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 10, nr 1, artikkel-id 12810Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current research on surface modifications has yielded advanced implant biomaterials. Various implant surface modifications have been shown to be promising in improving bone target cell response, but more comprehensive studies whether certain implant surface modifications can directly target cell behavioural features such as morphogenesis and proliferation are needed. Here, we studied the response of primary alveolar bone cells on various implant surface modifications in terms of osteoblast morphology and proliferation in vitro. Analyses of surface modifications led to surface-related test parameters including the topographical parameters micro-roughness, texture aspect and surface enlargement as well as the physicochemical parameter surface wettability. We compared osteoblast morphology and proliferation towards the above-mentioned parameters and found that texture aspect and surface enlargement but not surface roughness or wettability exhibited significant impact on osteoblast morphology and proliferation. Detailed analysis revealed osteoblast proliferation as a function of cell morphology, substantiated by an osteoblast size- and morphology-dependent increase in mitotic activity. These findings show that implant surface topography controls cell behavioural morphology and subsequently cell proliferation, thereby opening the road for cell instructive biomaterials. © 2020, The Author(s).

  • 39.
    Rabel, Kerstin
    et al.
    University of Freiburg, Germany.
    Nath, Amélie Joséphine
    University of Freiburg, Germany.
    Nold, Julian
    University of Freiburg, Germany.
    Spies, Benedikt C.
    University of Freiburg, Germany.
    Wesemann, Christian
    University of Freiburg, Germany.
    Altmann, Brigitte
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Witkowski, Siegbert
    University of Freiburg, Germany.
    Tomakidi, Pascal
    University of Freiburg, Germany.
    Steinberg, Thorsten
    University of Freiburg, Germany.
    Analysis of soft tissue integration-supportive cell functions in gingival fibroblasts cultured on 3D printed biomaterials for oral implant-supported prostheses2024Inngår i: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To date, it is unknown whether 3D printed fixed oral implant-supported prostheses can achieve comparable soft tissue integration (STI) to clinically established subtractively manufactured counterparts. STI is mediated among others by gingival fibroblasts (GFs) and is modulated by biomaterial surface characteristics. Therefore, the aim of the present work was to investigate the GF response of a 3D printed methacrylate photopolymer and a hybrid ceramic-filled methacrylate photopolymer for fixed implant-supported prostheses in the sense of supporting an STI. Subtractively manufactured samples made from methacrylate polymer and hybrid ceramic were evaluated for comparison and samples from yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), comprising well documented biocompatibility, served as control. Surface topography was analyzed by scanning electron microscopy and interferometry, elemental composition by energy-dispersive x-ray spectroscopy, and wettability by contact angle measurement. The response of GFs obtained from five donors was examined in terms of membrane integrity, adhesion, morphogenesis, metabolic activity, and proliferation behavior by a lactate-dehydrogenase assay, fluorescent staining, a resazurin-based assay, and DNA quantification. The results revealed all surfaces were smooth and hydrophilic. GF adhesion, metabolic activity and proliferation were impaired by 3D printed biomaterials compared to subtractively manufactured comparison surfaces and the 3Y-TZP control, whereas membrane integrity was comparable. Within the limits of the present investigation, it was concluded that subtractively manufactured surfaces are superior compared to 3D printed surfaces to support STI. For the development of biologically optimized 3D printable biomaterials, consecutive studies will focus on the improvement of cytocompatibility and the synthesis of STI-relevant extracellular matrix constituents.

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  • 40.
    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, Material och produktion, 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 reliability2017Inngår i: Acta Biomaterialia, ISSN 17427061, Vol. 48, s. 423-432Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 41.
    Schienle, Stefanie
    et al.
    Albert Ludwigs University, Germany.
    Al-Ahmad, Ali
    Albert Ludwigs University, Germany.
    Kohal, Ralf Joachim
    University of Freiburg, Germany.
    Bernsmann, Falk
    NTTF Coatings GmbH, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Montanaro, Laura
    Polytechnic University of Turin, Italy.
    Palmero, Paola
    Polytechnic University of Turin, Italy.
    Fürderer, Tobias
    DOCERAM Medical Ceramics GmbH, Germany.
    Chevalier, Jérôme
    University of Lyon, France.
    Hellwig, Elmar
    Albert Ludwigs University, Germany.
    Karygianni, Lamprini
    Albert Ludwigs University, Germany.
    Microbial adhesion on novel yttria-stabilized tetragonal zirconia (Y-TZP) implant surfaces with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coatings2016Inngår i: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 20, nr 7, s. 1719-1732Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 42.
    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, Material och produktion, IVF.
    Liu, Yihong
    Peking University School and Hospital of Stomatology, China.
    Kocjan, Andraz
    Jozef Stefan Institute, Slovenia.
    Fractography of self-glazed zirconia with improved reliability2017Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, ISSN 09552219, Vol. 37, nr 14, s. 4339-4345Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 43.
    Spies, B. C.
    et al.
    University of Freiburg, Germany.
    Maass, M. E.
    University of Freiburg, Germany.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, 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 fatigue2017Inngår i: Dental Materials, ISSN 01095641, Vol. 33, nr 8, s. 954-965Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 44.
    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, Material och produktion, 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 connection2018Inngår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 34, nr 10, s. 1585-1595Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 45.
    Svensson, T.
    et al.
    Lund University.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Lewander, M.
    Lund University.
    Xu, C.T.
    Lund University.
    Svanberg, S.
    Lund University.
    Disordered, strongly scattering porous materials as miniature multipass gas cells2011Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, nr 14Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 46.
    Svensson, Tomas
    et al.
    European Laboratory for Non-linear Spectroscopy (LENS), Italy; Lund University, Sweden.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Burresi, Matteo
    European Laboratory for Non-linear Spectroscopy (LENS), Italy.
    Savo, Romolo
    European Laboratory for Non-linear Spectroscopy (LENS), Italy.
    Xu, Can T.
    Lund University, Sweden.
    Wiersma, Diederik S.
    European Laboratory for Non-linear Spectroscopy (LENS), Italy.
    Svanberg, Sune
    Lund University, Sweden.
    Pore size assessment based on wall collision broadening of spectral lines of confined gas: Experiments on strongly scattering nanoporous ceramics with fine-tuned pore sizes2013Inngår i: Applied Physics B: Lasers and Optics, 2013, Vol. 110, nr 2, s. 147-154Konferansepaper (Fagfellevurdert)
    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. 

  • 47.
    Svensson, Tomas
    et al.
    University of Florence, Italy.
    Vynck, Kevin
    University of Florence, Italy; CNRS ESPCI ParisTech, France.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Farina, Andrea
    Istituto di Fotonica e Nanotecnologie (IFN-CNR), Italy.
    Pifferi, Antonio
    Istituto di Fotonica e Nanotecnologie (IFN-CNR), Italy; Politecnico di Milano, Italy.
    Wiersma, Diederik S.
    University of Florence, Italy; Istituto Nazionale di Ottica (CNR-INO), Italy.
    Light diffusion in quenched disorder: Role of step correlations2014Inngår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 89, nr 2, artikkel-id 022141Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 48.
    Tönnäng, Lenny
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Adolfsson, Erik
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Malmström, J.
    Oral and Maxillofacial Unit Halmstad.
    Abrahamsson, P.
    Oral and Maxillofacial Unit Halmstad.
    3D printed versus machined zirconia for dental applications2015Konferansepaper (Annet vitenskapelig)
  • 49.
    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, Material och produktion, IVF.
    Ultracompact oxygen sensor using nanoporous materials as strongly scattering multipass cell for tunable diode laser absorption spectroscopy2017Inngår i: Optics InfoBase Conference Papers, 2017Konferansepaper (Fagfellevurdert)
    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.

  • 50.
    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, Material och produktion, IVF, Keramer.
    Characterization of strongly scattering nanoporous materials as miniaturized multipass cell for tunable diode laser absorption spectroscopy2017Inngår i: Applied Physics B: Lasers and Optics, ISSN 09462171, Vol. 123, nr 4, artikkel-id 136Artikkel i tidsskrift (Fagfellevurdert)
    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.

12 1 - 50 of 53
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