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Mölndal, Sweden

Halldin A.,Malmo University | Ander M.,Chalmers University of Technology | Jacobsson M.,Malmo University | Hansson S.,Dentsply Implants
BioMedical Engineering Online | Year: 2015

Background: When an implant is inserted in the bone the healing process starts to osseointegrate the implant by creating new bone that interlocks with the implant. Biomechanical interlocking capacity is commonly evaluated in in vivo experiments. It would be beneficial to find a numerical method to evaluate the interlocking capacity of different surface structures with bone. In the present study, the theoretical interlocking capacity of three different surfaces after different healing times was evaluated by the means of explicit finite element analysis. Methods: The surface topographies of the three surfaces were measured with interferometry and were used to construct a 3D bone-implant model. The implant was subjected to a displacement until failure of the bone-to-implant interface and the maximum force represents the interlocking capacity. Results: The simulated ratios (test/control) seem to agree with the in vivo ratios of Halldin et al. for longer healing times. However the absolute removal torque values are underestimated and do not reach the biomechanical performance found in the study by Halldin et al. which might be a result of unknown mechanical properties of the interface. Conclusion: Finite element analysis is a promising method that might be used prior to an in vivo study to compare the load bearing capacity of the bone-to-implant interface of two surface topographies at longer healing times. © 2015 Halldin et al. Source


Loberg J.,Dentsply Implants | Mattisson I.,Dentsply Implants | Ahlberg E.,Gothenburg University
Applied Surface Science | Year: 2014

In an attempt to reduce the need for animal studies in dental implant applications, a new model has been developed which combines well-known surface characterization methods with theoretical biomechanical calculations. The model has been named integrated biomechanical and topographical surface characterization (IBTSC), and gives a comprehensive description of the surface topography and the ability of the surface to induce retention strength with bone. IBTSC comprises determination of 3D-surface roughness parameters by using 3D-scanning electron microscopy (3D-SEM) and atomic force microscopy (AFM), and calculation of the ability of different surface topographies to induce retention strength in bone by using the local model. Inherent in this integrated approach is the use of a length scale analysis, which makes it possible to separate different size levels of surface features. The IBTSC concept is tested on surfaces with different level of hierarchy, induced by mechanical as well as chemical treatment. Sequential treatment with oxalic and hydrofluoric acid results in precipitated nano-sized features that increase the surface roughness and the surface slope on the sub-micro and nano levels. This surface shows the highest calculated shear strength using the local model. The validity, robustness and applicability of the IBTSC concept are demonstrated and discussed. © 2013 The Authors. Source


Mattisson I.,Dentsply Implants | Gretzer C.,Dentsply Implants | Ahlberg E.,Gothenburg University
Materials Research Bulletin | Year: 2013

Newly designed implant surfaces with hierarchic structure have been characterized with respect to chemical composition, topography, electrical properties and cell culturing. Three levels of surface roughness are induced starting from a blasted surface with the naturally formed oxide layer. Dissolution of the blasted surface is obtained by chemical treatment in oxalic acid. The surface becomes smoother with multitude of shallow depressions in the walls and bottoms of the blasted structure. The surface oxide layer formed is somewhat thicker than the naturally formed oxide and may contain oxalate. In the final step, part of the oxide layer is dissolved in hydrofluoric acid leading to a high concentration of soluble titanium species. A nanostructured surface is formed by precipitation of titanium oxide at spots on the surface where locally the pH is increased due to hydrogen evolution. The surface roughness is only marginally changed by the chemical treatment while the conductivity of the surface layer is lower for the chemically treated surfaces compared with the blasted reference. The hierarchical structure mimics many natural processes for achieving high shear strength. © 2012 Elsevier Ltd. Source


Loberg J.,Gothenburg University | Gretzer C.,Dentsply Implants | Mattisson I.,Dentsply Implants | Ahlberg E.,Gothenburg University
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2014

For dental implants, improved osseointegration is obtained by modifying the surface roughness as well as oxide morphology and composition. A combination of different effects contributes to enhanced performance, but with surface roughness as the dominant factor. To single out the effect of oxide conductivity on biological response, oxide films with similar thickness and surface roughness but different electronic properties were formed using galvanostatic anodization. Three different current densities were used, 2.4, 4.8, and 11.9 mA cm-2, which resulted in growth rates ranging from 0.2 to 2.5 V s-1. The electronic properties were evaluated using cyclic voltammetry and impedance spectroscopy, while the biological response was studied by cell activity and apatite formation. The number of charge carrier in the oxide film close to the oxide/solution interface decreased from 5.8 × 10-19 to 3.2 × 10-19 cm-2 with increasing growth rate, that is, the conductivity decreased correspondingly. Cell response of the different surfaces was tested in vitro using human osteoblast-like cells (MG-63). The results clearly show decreased osteoblast proliferation and adhesion but higher mineralization activity for the oxide with lower conductivity at the oxide/solution interface. The apatite-forming ability was examined by immersion in simulated body fluid. At short times the apatite coverage was ∼26% for the anodized surfaces, significantly larger than for the reference with only 3% coverage. After 1 week of immersion the apatite coverage ranged from 73 to 56% and a slight differentiation between the anodized surfaces was obtained with less apatite formation on the surface with lower conductivity, in line with the cell culture results. © 2013 Wiley Periodicals, Inc. Source

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