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Mellgren, T., Qin, T., Öhman Mägi, C., Zhang, Y., Wu, B., Xia, W. & Engqvist, H. (2018). Calcium Phosphate Microspheres as a Delivery Vehicle for Tooth-Bleaching Agents. Journal of Dental Research, 97(3), 283-288
Open this publication in new window or tab >>Calcium Phosphate Microspheres as a Delivery Vehicle for Tooth-Bleaching Agents
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2018 (English)In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 97, no 3, p. 283-288Article in journal (Refereed) Published
Abstract [en]

Bleaching of vital teeth has become common practice in cosmetic dentistry today. Tooth sensitivity and demineralization of the enamel are, however, common side effects associated with hydrogen and carbamide peroxide bleaching. This study investigated if calcium phosphate microspheres, which have remineralizing properties, could be used as an additive without hindering the diffusion of the bleaching agent and if the spheres could be used as a carrier for carbamide peroxide. A remineralizing agent could increase the safety of bleaching and decrease the severity of its side effects. Comparisons between current hydrogen peroxide diffusion studies and previously published work are difficult since many studies include challenging-to-replicate conditions or lack reporting of important parameters. Hence, a diffusion model was designed by Wu Lab (School of Dentistry, University of California, Los Angeles) to measure the diffusion flux and determine the diffusivity of hydrogen peroxide. Physical parameters (e.g., diffusivity) could then be used for direct comparison to the results obtained by future studies. Three whitening gels with increasing amounts of spheres were formulated and tested with 2 commercially available whitening gels. The flux of hydrogen peroxide through 1-mm discs of bovine enamel was measured at steady-state conditions, and the diffusivity was calculated. The results showed that the spheres could be used as a carrier for carbamide peroxide and that the amount of spheres did not affect the diffusivity of peroxide through the enamel discs. Hence, the microspheres are considered promising as an additive to minimize side effects in bleaching gel formulation.

Place, publisher, year, edition, pages
SAGE PUBLICATIONS INC, 2018
Keywords
dental enamel, diffusion, peroxide, tooth whitening, tooth sensitivity, tooth remineralization
National Category
Dentistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-352988 (URN)10.1177/0022034517741295 (DOI)000429319800006 ()29125909 (PubMedID)
Funder
Swedish Research Council, 20135419
Available from: 2018-07-17 Created: 2018-07-17 Last updated: 2018-07-25Bibliographically approved
Häggmark, I., Romell, J., Lewin, S., Öhman-Mägi, C. & Hertz, H. (2018). Cellular-Resolution Imaging of Microstructures in Rat Bone using Laboratory Propagation-Based Phase-Contrast X-ray Tomography. In: Proceedings of the 14th International Conference on X-ray Microscopy (XRM2018): . Paper presented at 14th International Conference on X-ray Microscopy, Saskatoon (Canada) 2018.
Open this publication in new window or tab >>Cellular-Resolution Imaging of Microstructures in Rat Bone using Laboratory Propagation-Based Phase-Contrast X-ray Tomography
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2018 (English)In: Proceedings of the 14th International Conference on X-ray Microscopy (XRM2018), 2018Conference paper, Poster (with or without abstract) (Refereed)
Series
Proceedings of the 14th International Conference on X-ray Microscopy (XRM2018)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-368493 (URN)10.1017/S1431927618014137P (DOI)
Conference
14th International Conference on X-ray Microscopy, Saskatoon (Canada) 2018
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2018-12-06
Robo, C., Öhman, C. & Persson, C. (2018). Compressive fatigue properties of commercially available standard and low-modulus acrylic bone cements intended for vertebroplasty. Journal of The Mechanical Behavior of Biomedical Materials, 82, 70-76
Open this publication in new window or tab >>Compressive fatigue properties of commercially available standard and low-modulus acrylic bone cements intended for vertebroplasty
2018 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 82, p. 70-76Article in journal (Refereed) Published
Abstract [en]

Vertebroplasty (VP) is a minimally invasive surgical procedure commonly used to relieve severe back pain associated with vertebral compression fractures. The poly(methyl methacrylate) bone cement used during this procedure is however presumed to facilitate the occurrence of additional fractures next to the treated vertebrae. A reason for this is believed to be the difference in stiffness between the bone cement and the surrounding trabecular bone. The use of bone cements with lower mechanical properties could therefore reduce the risk of complications post-surgery. While intensive research has been performed on the quasi-static mechanical properties of these cements, there is no data on their long-term mechanical properties. In the present study, the in vitrocompressive fatigue performance as well as quasi-static mechanical properties of two commercially available acrylic bone cements - a low-modulus cement (Resilience®) and a standard cement (F20) from the same manufacturer - were determined. The quasi-static mechanical properties of the low-modulus and standard cements after 24h of setting were in the range of other vertebroplastic cements (σ=70-75 MPa; E=1600-1900 MPa). F20 displayed similar mechanical properties over time in 37˚C phosphate buffered saline solution, while the mechanical properties of the Resilience®cement decreased gradually due to an increased porosity in the polymeric matrix. The standard cement exhibited a fatigue limit of approx. 47 MPa, whereas the low-modulus cement showed a fatigue limit of approx. 31 MPa. 

In summary, the low-modulus bone cement had a lower fatigue limit than the standard cement, as expected. However, this fatigue limit is still substantially higher than the stresses experienced by vertebral trabecular bone.  

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Acrylic bone cement, low-modulus, elastic modulus, compression, fatigue, vertebroplasty
National Category
Other Materials Engineering Biomaterials Science Medical Materials
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-349032 (URN)10.1016/j.jmbbm.2018.03.001 (DOI)000432508800009 ()
Funder
The Royal Swedish Academy of Sciences, FOA13H-141
Available from: 2018-04-20 Created: 2018-04-20 Last updated: 2018-12-05
Sladkova, M., Pujari-Palmer, M., Öhman, C., Cheng, J., Al-Ansari, S., Saad, M., . . . de Peppo, G. M. (2018). Engineering human bone grafts with new macroporous calcium phosphate cement scaffolds. Journal of Tissue Engineering and Regenerative Medicine, 12(3), 715-726
Open this publication in new window or tab >>Engineering human bone grafts with new macroporous calcium phosphate cement scaffolds
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2018 (English)In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, E-ISSN 1932-7005, Vol. 12, no 3, p. 715-726Article in journal (Refereed) Published
Abstract [en]

Bone engineering opens the possibility to grow large amounts of tissue products by combining patient-specific cells with compliant biomaterials. Decellularized tissue matrices represent suitable biomaterials, but availability, long processing time, excessive cost, and concerns on pathogen transmission have led to the development of biomimetic synthetic alternatives. We recently fabricated calcium phosphate cement (CPC) scaffolds with variable macroporosity using a facile synthesis method with minimal manufacturing steps and demonstrated long-term biocompatibility in vitro. However, there is no knowledge on the potential use of these scaffolds for bone engineering and whether the porosity of the scaffolds affects osteogenic differentiation and tissue formation in vitro. In this study, we explored the bone engineering potential of CPC scaffolds with two different macroporosities using human mesenchymal progenitors derived from induced pluripotent stem cells (iPSC-MP) or isolated from bone marrow (BMSC). Biomimetic decellularized bone scaffolds were used as reference material in all experiments. The results demonstrate that, irrespective of their macroporosity, the CPC scaffolds tested in this study support attachment, viability, and growth of iPSC-MP and BMSC cells similarly to decellularized bone. Importantly, the tested materials sustained differentiation of the cells as evidenced by increased expression of osteogenic markers and formation of a mineralized tissue. In conclusion, the results of this study suggest that the CPC scaffolds fabricated using our method are suitable to engineer bone grafts from different cell sources and could lead to the development of safe and more affordable tissue grafts for reconstructive dentistry and orthopaedics and in vitro models for basic and applied research.

National Category
Other Medical Engineering
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-335996 (URN)10.1002/term.2491 (DOI)000427137100061 ()28635177 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme
Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2018-06-04Bibliographically approved
Lewin, S., Gallinetti, S., Kihlström, L., Persson, C., Birgersson, U. & Öhman, C. (2018). Evaluation of bioactive cranial implants: preliminary results from volumetric quantifications using computed tomography (CT). In: : . Paper presented at 8th World Congress of Biomechanics, 2018 Dublin.
Open this publication in new window or tab >>Evaluation of bioactive cranial implants: preliminary results from volumetric quantifications using computed tomography (CT)
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2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Engineering and Technology Medical Materials
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-368419 (URN)
Conference
8th World Congress of Biomechanics, 2018 Dublin
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2018-12-11
Ajaxon, I., Holmberg, A., Öhman, C. & Persson, C. (2018). Fatigue performance of a high-strength, degradable calcium phosphate bone cement. Journal of The Mechanical Behavior of Biomedical Materials, 79, 46-52
Open this publication in new window or tab >>Fatigue performance of a high-strength, degradable calcium phosphate bone cement
2018 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 79, p. 46-52Article in journal (Refereed) Published
Abstract [en]

Calcium phosphate cements (CPCs) are clinically used as injectable materials to fill bone voids and to improve hardware fixation in fracture surgery. In vivo they are dynamically loaded; nonetheless little is known about their fatigue properties. The aim of this study was to, for the first time, investigate the fatigue performance of a high strength, degradable (brushitic) CPC, and also evaluate the effect of cement porosity (by varying the liquid to powder ratio, L/P) and the environment (air at room temperature or in a phosphate buffered saline solution, PBS, at 37 degrees C) on the fatigue life. At a maximum compressive stress level of 15 MPa, the cements prepared with an L/P-ratio of 0.22 and 0.28 ml/g, corresponding to porosities of approximately 12% and 20%, had a 100% probability of survival until run-out of 5 million cycles, in air. When the maximum stress level, or the L/P-ratio, was increased, the probability of survival decreased. Testing in PBS at 37 degrees C led to more rapid failure of the specimens. However, the high-strength cement had a 100% probability of survival up to approximately 2.5 million cycles at a maximum compressive stress level of 10 MPa in PBS, which is substantially higher than some in vivo stress levels, e.g., those found in the spine. At 5 MPa in PBS, all specimens survived to run-out. The results found herein are important if clinical use of the material is to increase, as characterisation of the fatigue performance of CPCs is largely lacking from the literature.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Bone cement, Calcium phosphate, Brushite, Fatigue, Compression, Porosity, Mechanical properties
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-347539 (URN)10.1016/j.jmbbm.2017.12.005 (DOI)000425072300006 ()29272812 (PubMedID)
Funder
Swedish Research Council, 621-2011-6258
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-09Bibliographically approved
Lewin, S., Gallinetti, S., Persson, C., Kihlström, L., Birgerson, U. & Öhman, C. (2018). Longitudinal assessment of trends in calcium phosphate degradation for cranial implants: preliminary results from two patients. In: : . Paper presented at The Scandinavian Society for Biomaterials 2018, 11th annual meeting.
Open this publication in new window or tab >>Longitudinal assessment of trends in calcium phosphate degradation for cranial implants: preliminary results from two patients
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2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Engineering and Technology Medical Materials
Research subject
Engineering Science with specialization in Materials Science; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-368412 (URN)
Conference
The Scandinavian Society for Biomaterials 2018, 11th annual meeting
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2018-12-11
Barba, A., Maazouz, Y., Diez-Escudero, A., Rappe, K., Espanol, M., Montufar, E., . . . Ginebra, M.-P. (2018). Osteogenesis by foamed and 3D-printed nanostructured calcium phosphate scaffolds: Effect of pore architecture. Acta Biomaterialia, 79, 135-147
Open this publication in new window or tab >>Osteogenesis by foamed and 3D-printed nanostructured calcium phosphate scaffolds: Effect of pore architecture
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2018 (English)In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 79, p. 135-147Article in journal (Refereed) Published
Abstract [en]

There is an urgent need of synthetic bone grafts with enhanced osteogenic capacity. This can be achieved by combining biomaterials with exogenous growth factors, which however can have numerous undesired side effects, but also by tuning the intrinsic biomaterial properties. In a previous study, we showed the synergistic effect of nanostructure and pore architecture of biomimetic calcium deficient hydroxyapatite (CDHA) scaffolds in enhancing osteoinduction, i.e. fostering the differentiation of mesenchymal stem cells to bone forming cells. This was demonstrated by assessing bone formation after implanting the scaffolds intramuscularly. The present study goes one step forward, since it analyzes the effect of the geometrical features of the same CDHA scaffolds, obtained either by 3D-printing or by foaming, on the osteogenic potential and resorption behaviour in a bony environment. After 6 and 12 weeks of intraosseous implantation, both bone formation and material degradation had been drastically affected by the macropore architecture of the scaffolds. Whereas nanostructured CDHA was shown to be highly osteoconductive both in the robocast and foamed scaffolds, a superior osteogenic capacity was observed in the foamed scaffolds, which was associated with their higher intrinsic osteoinductive potential. Moreover, they showed a significantly higher cell-mediated degradation than the robocast constructs, with a simultaneous and progressive replacement of the scaffold by new bone. In conclusion, these results demonstrate that the control of macropore architecture is a crucial parameter in the design of synthetic bone grafts, which allows fostering both material degradation and new bone formation. Statement of Significance 3D-printing technologies open new perspectives for the design of patient-specific bone grafts, since they allow customizing the external shape together with the internal architecture of implants. In this respect, it is important to design the appropriate pore geometry to maximize the bone healing capacity of these implants. The present study analyses the effect of pore architecture of nanostructured hydroxyapatite scaffolds, obtained either by 3D-printing or foaming, on the osteogenic potential and scaffold resorption in an in vivo model. While nanostructured hydroxyapatite showed excellent osteoconductive properties irrespective of pore geometry, we demonstrated that the spherical, concave macropores of foamed scaffolds significantly promoted both material resorption and bone regeneration compared to the 3D-printed scaffolds with orthogonal-patterned struts and therefore prismatic, convex macropores.

National Category
Ceramics Medical Materials Biomaterials Science
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-369168 (URN)10.1016/j.actbio.2018.09.003 (DOI)000447477600009 ()
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-14Bibliographically approved
Lewin, S., Riben, C., Thor, A. & Öhman-Mägi, C. (2018). Quantification of radiological changes around dental implants: a CBCT image analysis workflow. In: : . Paper presented at The 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and the 3rd Conference on Imaging and Visualization.
Open this publication in new window or tab >>Quantification of radiological changes around dental implants: a CBCT image analysis workflow
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Engineering and Technology Medical Materials
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-368398 (URN)
Conference
The 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and the 3rd Conference on Imaging and Visualization
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2018-12-11
Ajaxon, I., Öhman Mägi, C. & Persson, C. (2017). Compressive fatigue properties of an acidic calcium phosphate cement—effect of phase composition. Journal of materials science. Materials in medicine, 28(3), Article ID 41.
Open this publication in new window or tab >>Compressive fatigue properties of an acidic calcium phosphate cement—effect of phase composition
2017 (English)In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 28, no 3, article id 41Article in journal (Refereed) Published
Abstract [en]

Calcium phosphate cements (CPCs) are synthetic bone grafting materials that can be used in fracture stabilization and to fill bone voids after, e.g., bone tumour excision. Currently there are several calcium phosphate-based formulations available, but their use is partly limited by a lack of knowledge of their mechanical properties, in particular their resistance to mechanical loading over longer periods of time. Furthermore, depending on, e.g., setting conditions, the end product of acidic CPCs may be mainly brushite or monetite, which have been found to behave differently under quasi-static loading. The objectives of this study were to evaluate the compressive fatigue properties of acidic CPCs, as well as the effect of phase composition on these properties. Hence, brushite cements stored for different lengths of time and with different amounts of monetite were investigated under quasi-static and dynamic compression. Both storage and brushite-to-monetite phase transformation was found to have a pronounced effect both on quasi-static compressive strength and fatigue performance of the cements, whereby a substantial phase transformation gave rise to a lower mechanical resistance. The brushite cements investigated in this study had the potential to survive 5 million cycles at a maximum compressive stress of 13 MPa. Given the limited amount of published data on fatigue properties of CPCs, this study provides an important insight into the compressive fatigue behaviour of such materials. 

Keywords
Bone cement, brushite, monetite, fatigue, mechanical properties
National Category
Ceramics Medical Materials Biomaterials Science
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-314237 (URN)10.1007/s10856-017-5851-5 (DOI)000394242700006 ()28144853 (PubMedID)
Funder
Swedish Research Council, 621-2011-6258
Available from: 2017-02-03 Created: 2017-01-31 Last updated: 2017-11-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2709-9541

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