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The synergistic role of hierarchical macro- and mesoporous implant surface and microscopic view of enhanced osseointegration
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The trend for designing of a titanium implant explored using different chemical compositions and crystallinity materials until people realized that the implant surface character was another important factor affecting the rate and extent of osseointegartion. Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5μm. An additional mesoporous titania top layer was created that followed the contour of the macropores and having 100–200 nm thickness and a pore diameter of 10 nm. Thus, a coherent laminar titania surface layer was obtained producing a hierarchical macro- and mesoporous surface. The interfacial bonding between the surface layers and the titanium matrix was characterized by a scratch test that confirmed a stable and strong bonding of the laminar titania surface layers upon titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy (SEM). A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, when compared with the titania surface with solo porosity scale topography.

For the in vivo results of the evaluation of osseointegration, an argon ion beam polishing technique was applied to prepare the cross sections of implants feasible for the high resolution SEM investigation. The interfacial microstructure between newly formed bone and implants with four modified surfaces including the new hierarchical macro- and mesoporous implant surface retrieved after in vivo tests were characterized. By this approach it has become possible to directly observe early bone formation, the increase of bone density, and the evolution of bone structure. The two bone growth mechanisms, distant osteogenesis and contact osteogenesis, can also be distinguished. These direct observations give, at microscopic level, a better view of osseointegration and explain the functional mechanisms of various implant surfaces for osseointegration.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry, Stockholm University , 2015. , 61 p.
Keyword [en]
Porosity, cell adhesion, cell proliferation, surface topography, implant, bone-implant interface, argon ion beam polishing, osteogenesis, osseointegration
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-120584ISBN: 978-91-7649-267-3 (print)OAI: oai:DiVA.org:su-120584DiVA: diva2:853621
Public defence
2015-10-22, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.

Available from: 2015-09-30 Created: 2015-09-14 Last updated: 2015-09-15Bibliographically approved
List of papers
1. Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization
Open this publication in new window or tab >>Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization
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2015 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 47, 376-383 p.Article in journal (Refereed) Published
Abstract [en]

Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 gm. An additional mesoporous titania top layer following the contour of the macropores, of 100-200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography.

Keyword
Porosity, Titanium oxide, Cell adhesion, Cell proliferation, Surface topography
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-112844 (URN)10.1016/j.msec.2014.11.021 (DOI)000347581600045 ()
Available from: 2015-01-16 Created: 2015-01-16 Last updated: 2017-12-05Bibliographically approved
2. Microscopic view of osseointegration and functional mechanisms of implant surfaces
Open this publication in new window or tab >>Microscopic view of osseointegration and functional mechanisms of implant surfaces
2015 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 56, 380-385 p.Article in journal (Refereed) Published
Abstract [en]

Argon ion beam polishing technique was applied to prepare the cross sections of implants feasible for high resolution scanning electron microscope investigation. The interfacial microstructure between newly formed bone and implants with three modified surfaces retrieved after in vivo test using three different animal models was characterized. By this approach it has become possible to directly observe early bone formation, the increase of bone density, and the evolution of bone structure. The two bone growth mechanisms, distant osteogenesis and contact osteogenesis, can also be distinguished. These direct observations give, at microscopic level, a better view of osseointegration and expound the functional mechanisms of various implant surfaces for osseointegration.

Keyword
Implant, Bone–implant interface, Osseointegration, Argon ion beam polishing, Osteogenesis
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-120279 (URN)10.1016/j.msec.2015.06.053 (DOI)000359873900046 ()
Available from: 2015-09-04 Created: 2015-09-04 Last updated: 2017-12-04Bibliographically approved
3. Biomineralization stimulated peri-titanium implants prepared by selective laser melting
Open this publication in new window or tab >>Biomineralization stimulated peri-titanium implants prepared by selective laser melting
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(English)In: Journal of Materiomics, ISSN 2352-8478Article in journal (Refereed) In press
Abstract [en]

Titanium implants prepared by selective laser melting (SLM), a method of additive manufacturing, were subjected to implantation in beagle dogs for two and four weeks. Argon ion beam-polished cross sections of the implants after in vivo tests were characterized by scanning electron microscope (SEM) to evaluate the bone–implant interface and the early peri-implant biomineralization with sufficiently improved resolution. Two bone mineralization mechanisms were disclosed. As early as two weeks after implantation, a layer of new bone was found to form directly on the implant surface and bone in-growth was also observed. Osseointegration was found to establish partly at the tip of the implants. After healing for four weeks it was found that osseointegration was established around the entire tip of the implants, whereas only partly at the third thread region of the implants. The experimental evidences observed reveal that an inherent highly porous surface of the titanium implants generated by selective laser melting is favorable for new bone apposition.

Keyword
Biomineralization, Selective laser melting (SLM), Bone–implant interface, Osseointegration
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-120277 (URN)10.1016/j.jmat.2015.07.008 (DOI)
Available from: 2015-09-04 Created: 2015-09-04 Last updated: 2015-09-14Bibliographically approved
4. Quartz crystal microbalance titanium sensor with mesoporous pores
Open this publication in new window or tab >>Quartz crystal microbalance titanium sensor with mesoporous pores
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The quartz crystal microbalance (QCM) is an effective tool for the surface study in real time. But mesoporous coating materials usually is thin layer and stick to the substrates, and its properties cannot be studied by conventional methods as other mesoporous materials. A new QCM sensor with mesoporous pores is expected. The new mesoporous QCM sensor has mesoporous titania coating with 200 nm thickness only on the active electrode side by the method with masking counter electrode side during dip-coating. The new mesoporous QCM sensor works well in Q-Sense E1 equipment.

National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-120541 (URN)
Available from: 2015-09-11 Created: 2015-09-11 Last updated: 2016-02-17Bibliographically approved

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