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Li, D., Liu, Y., Zhong, Y., Liu, L., Adolfsson, E. & Shen, Z. (2019). Dense and strong ZrO2 ceramics fully densified in <15 min. Advances in Applied Ceramics: Structural, Functional and Bioceramics, 118(1-2), 23-29
Open this publication in new window or tab >>Dense and strong ZrO2 ceramics fully densified in <15 min
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2019 (English)In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 118, no 1-2, p. 23-29Article in journal (Refereed) Published
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. 

Keywords
Bioceramics, mechanical properties, microstructure, sintering by intense thermal radiation (SITR), spark plasma sintering, toughness, Vickers hardness, Bending strength, Heat radiation, Zirconia, Dental applications, Fine-grained microstructure, Fracture surfaces, Indentation toughness, Natural surface, Relative density, XRD analysis, Zirconia ceramic, Density (specific gravity)
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33764 (URN)10.1080/17436753.2018.1449580 (DOI)2-s2.0-85044923351 (Scopus ID)
Available from: 2018-05-04 Created: 2018-05-04 Last updated: 2019-06-17Bibliographically approved
Spies, B. C., Fross, A., Adolfsson, E., Bagegni, A., Doerken, S. & Kohal, R.-J. (2018). Stability and aging resistance of a zirconia oral implant using a carbon fiber-reinforced screw for implant-abutment connection. Dental Materials, 34(10), 1585-1595
Open this publication in new window or tab >>Stability and aging resistance of a zirconia oral implant using a carbon fiber-reinforced screw for implant-abutment connection
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2018 (English)In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 34, no 10, p. 1585-1595Article in journal (Refereed) Published
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.

Keywords
Ceramics, Crystallography, Dental implant, Scanning electron microscopy, Zirconia
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35141 (URN)10.1016/j.dental.2018.08.290 (DOI)30180975 (PubMedID)2-s2.0-85052797091 (Scopus ID)
Available from: 2018-09-11 Created: 2018-09-11 Last updated: 2019-06-17Bibliographically approved
Altmann, B., Karygianni, L., Al-Ahmad, A., Butz, F., Bächle, M., Adolfsson, E., . . . Kohal, R. J. (2017). Assessment of Novel Long-Lasting Ceria-Stabilized Zirconia-Based Ceramics with Different Surface Topographies as Implant Materials. Advanced Functional Materials, 27(40), Article ID 1702512.
Open this publication in new window or tab >>Assessment of Novel Long-Lasting Ceria-Stabilized Zirconia-Based Ceramics with Different Surface Topographies as Implant Materials
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2017 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 27, no 40, article id 1702512Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2017
Keywords
Alumina, Biocompatibility, Ceramic materials, Surface topography, Zirconia, Bacterial adhesion, Human osteoblast, Implant materials, Osseointegration, Zirconia based composites, Yttria stabilized zirconia
National Category
Medical Materials
Identifiers
urn:nbn:se:ri:diva-30368 (URN)10.1002/adfm.201702512 (DOI)2-s2.0-85026730768 (Scopus ID)
Available from: 2017-08-23 Created: 2017-08-23 Last updated: 2019-06-17Bibliographically approved
Altmann, B., Rabel, K., Kohal, R. J., Proksch, S., Tomakidi, P., Adolfsson, E., . . . Steinberg, T. (2017). Cellular transcriptional response to zirconia-based implant materials. Dental Materials, 33(2), 241-255
Open this publication in new window or tab >>Cellular transcriptional response to zirconia-based implant materials
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2017 (English)In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 33, no 2, p. 241-255Article in journal (Refereed) Published
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.

Keywords
Alveolar bone osteoblasts, Gingiva fibroblasts, Gene profiling, Zirconia composite, Dental implants
National Category
Materials Engineering Medical Engineering
Identifiers
urn:nbn:se:ri:diva-29892 (URN)10.1016/j.dental.2016.12.005 (DOI)2-s2.0-85009215296 (Scopus ID)
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2019-06-17Bibliographically approved
Venturini, F., Schönherr, V., Rey, J. M. & Adolfsson, E. (2017). Characterization of strongly scattering nanoporous materials as miniaturized multipass cell for tunable diode laser absorption spectroscopy. Applied Physics B: Lasers and Optics, 123(4), Article ID 136.
Open this publication in new window or tab >>Characterization of strongly scattering nanoporous materials as miniaturized multipass cell for tunable diode laser absorption spectroscopy
2017 (English)In: Applied Physics B: Lasers and Optics, ISSN 09462171, Vol. 123, no 4, article id 136Article in journal (Refereed) Published
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.

Keywords
Absorption spectroscopy, Ceramic materials, Characterization, Infrared devices, Light absorption, Nanopores, Plasma interactions, Porous materials, Zirconium alloys
National Category
Ceramics
Identifiers
urn:nbn:se:ri:diva-29422 (URN)10.1007/s00340-017-6705-z (DOI)2-s2.0-85017324132 (Scopus ID)
Available from: 2017-05-03 Created: 2017-05-03 Last updated: 2019-06-17Bibliographically approved
Fornabaio, M., Reveron, H., Adolfsson, E., Montanaro, L., Chevalier, J. & Palmero, P. (2017). Design and development of dental ceramics: Examples of current innovations and future concepts (1ed.). In: Palmero, P., Cambier, F., De Barra, E. (Ed.), Advances in Ceramic Biomaterials: Materials, Devices and Challenges (pp. 355-389). Elsevier Inc.
Open this publication in new window or tab >>Design and development of dental ceramics: Examples of current innovations and future concepts
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2017 (English)In: Advances in Ceramic Biomaterials: Materials, Devices and Challenges / [ed] Palmero, P., Cambier, F., De Barra, E., Elsevier Inc. , 2017, 1, p. 355-389Chapter in book (Other academic)
Place, publisher, year, edition, pages
Elsevier Inc., 2017 Edition: 1
National Category
Ceramics
Identifiers
urn:nbn:se:ri:diva-33839 (URN)10.1016/B978-0-08-100881-2.00025-7 (DOI)2-s2.0-85044113649 (Scopus ID)9780081008829 (ISBN)9780081008812 (ISBN)
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2019-06-17Bibliographically approved
Shen, Z., Liu, L., Xu, X., Zhao, J., Eriksson, M., Zhong, Y., . . . Kocjan, A. (2017). Fractography of self-glazed zirconia with improved reliability. Journal of the European Ceramic Society, 37(14), 4339-4345
Open this publication in new window or tab >>Fractography of self-glazed zirconia with improved reliability
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2017 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, ISSN 09552219, Vol. 37, no 14, p. 4339-4345Article in journal (Refereed) Published
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.

Keywords
Defects, Dental restorations, Fractography, Nanoceramics, Self-glazed zirconia
National Category
Ceramics
Identifiers
urn:nbn:se:ri:diva-29404 (URN)10.1016/j.jeurceramsoc.2017.03.008 (DOI)2-s2.0-85015772890 (Scopus ID)
Available from: 2017-04-26 Created: 2017-04-26 Last updated: 2019-06-17Bibliographically approved
Dehestani, M., Zemlyanov, D. Y., Adolfsson, E. & Stanciu, L. A. (2017). Improving bioactivity of inert bioceramics by a novel Mg-incorporated solution treatment. Applied Surface Science, 425, 564-575
Open this publication in new window or tab >>Improving bioactivity of inert bioceramics by a novel Mg-incorporated solution treatment
2017 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 425, p. 564-575Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
Elsevier B.V., 2017
Keywords
Alumina, Apatite, Bioactivity, Bioceramics, Bone, Ceramic materials, Chemical bonds, Hydroxyapatite, Phosphate minerals, Photodegradation, Surface chemistry, Temperature, X ray photoelectron spectroscopy, Zirconia, Composite substrate, Low temperature aging, Orthopedic applications, Phase identification, Simulated body fluids, Solution treatments, Stabilized zirconia, Surface bioactivity, Yttria stabilized zirconia
National Category
Medical Materials Ceramics
Identifiers
urn:nbn:se:ri:diva-31238 (URN)10.1016/j.apsusc.2017.07.009 (DOI)2-s2.0-85027861365 (Scopus ID)
Available from: 2017-09-15 Created: 2017-09-15 Last updated: 2019-06-17Bibliographically approved
Johansson, E., Lidström, O., Lyckfeldt, O., Adolfsson, E. & Jan, J. (2017). Influence of Resin Composition on the Defect Formation in Alumina Manufactured by Stereolithography. Materials, 10(2), Article ID 138.
Open this publication in new window or tab >>Influence of Resin Composition on the Defect Formation in Alumina Manufactured by Stereolithography
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2017 (English)In: Materials, ISSN ISSN 1996-1944, Vol. 10, no 2, article id 138Article in journal (Refereed) Published
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.

Keywords
ceramics, stereolithography, DLP, thermal debinding, photopolymerization
National Category
Ceramics
Identifiers
urn:nbn:se:ri:diva-28199 (URN)10.3390/ma10020138 (DOI)2-s2.0-85013789184 (Scopus ID)
Available from: 2017-03-09 Created: 2017-03-09 Last updated: 2019-06-17Bibliographically approved
Spies, B. C., Maass, M. E., Adolfsson, E., Sergo, V., Kiemle, T., Berthold, C., . . . Kohal, R.-J. -. (2017). Long-term stability of an injection-molded zirconia bone-level implant: A testing protocol considering aging kinetics and dynamic fatigue. Dental Materials, 33(8), 954-965
Open this publication in new window or tab >>Long-term stability of an injection-molded zirconia bone-level implant: A testing protocol considering aging kinetics and dynamic fatigue
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2017 (English)In: Dental Materials, ISSN 01095641, Vol. 33, no 8, p. 954-965Article in journal (Refereed) Published
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.

Keywords
Ceramics, Crystallography, Dental implant, Raman spectroscopy, Scanning electron microscopy, X-ray diffraction, Zirconia
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-30168 (URN)10.1016/j.dental.2017.06.002 (DOI)2-s2.0-85020867061 (Scopus ID)
Available from: 2017-08-01 Created: 2017-08-01 Last updated: 2019-06-17Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-4860-8763

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