Novel multiphasic calcium phosphate cements with enhanced degradative properties

Event Abstract Back to Event Novel multiphasic calcium phosphate cements with enhanced degradative properties Sara Gallinetti1, Delphine Lemoine1 and Caroline Öhman Mägi1 1 Uppsala University, Division of Applied Materials Science, Department of Engineering Sciences, Sweden Introduction: Among the available biomaterials, calcium phosphate cements, such as hydroxyapatite (HA) and brushite, are of high interest due to their many advantages, e.g. bioactive, osteoconductive, osteotransductive, injectable and self-setting in vivo. Still, although they are biodegradable, degradation rate is a problem since the very slow degradation of HA inhibits bone ingrowth and the rapid degradation of brushite disrupts mechanical stability. Recently, some attempts to produce biphasic cements composed by HA and β-tricalcium phosphate (β-TCP) have been performed[1],[2]. However, no improvement in dissolution rate was found[2]. The answer might be adding an even more soluble phase, e.g. brushite. This work aims at designing new multiphasic calcium phosphate cements (MCPCs) with improved degradative properties. Materials and Methods: All cements were based on a HA cement prepared by mixing α-tricalcium phosphate (α-TCP) with a 2.5 wt% Na2HPO4-solution (L/P = 0.35 ml/g). Two different methods were used to produce the MCPCs: 1) 20 mol% monocalcium phosphate monohydrate:ß-TCP (1:1 molar ratio) was added to the powder phase (80 mol% HA); 2) 35 wt% or 50 wt% of crushed set brushite[3] particles (SBPs) were added to the powder phase (L/P was adjusted to 0.20 and 0.19 ml/g, respectively). Specimens were let to set in PBS for 48 h. Setting times were determined with Gillmore needles. Wet specimens were tested in compression. Phase composition was analysed with XRD and Rietveld refinement using Profex. An accelerated mass degradation was attained by placing cement samples in a solution of pH = 2 containing hydrochloric acid for 8 h. The weight of the samples was monitored over time. Results and Discussion: Both methods resulted in mouldable cements. Setting times for the MCPCs were comparable or slightly shorter than those for the pure HA cement. The compressive strength of the MCPCs was in general slightly lower, however the cement containing 35 wt% SBP had a comparable strength to the pure HA. Rietveld refinement reviled that the MCPCs were not only biphasic but multiphasic. All three compositions did not only consist of HA and brushite, but octacalcium phosphate (OCP) and unreacted α-TCP and ß-TCP were also present. Small amounts of beta-dicalcium pyrophosphate (ß-SPP) were also found, due to impurities in the ß-TCP powder. OCP is a precursor of hydroxyapatite and would probably have transform into HA if the samples had been let to set for a longer time[4]. All samples started to dissolve in the degradation solution. Furthermore, the samples containing SBP degraded significantly faster than the pure HA and the 80 mol% HA samples. Conclusions: It was possible to obtain multiphasic calcium phosphate cements with two different methods. The cement containing 35 wt% of set brushite particles showed promising preliminary results. It maintained approximately the same setting times and compressive strength as pure HA, at the same time as an increased degradation rate was achieved. However, further studies to optimise and fully characterise this multiphasic calcium phosphate cement are needed. This work was supported in part by Carl Tryggers Stiftelse (grant CTS 13:533).References:[1] Lopez-Heredia et al. Acta Biomater. 2012; 8(9): 3500-3508.[2] Gallinetti et al. J. of Am. Ceram. Soc. 2014; 97(4): 1085-1073.[3] Unosson et al. Bioceram Dev Appl 2014; 4: 074.[4] Ginebra et al. Biomaterials. 2004; 25(17):3453–3462. Keywords: Calcium phosphate, material design, mechanical property, Biodegradable material Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: General Session Oral Topic: Ceramics Citation: Gallinetti S, Lemoine D and Öhman Mägi C (2016). Novel multiphasic calcium phosphate cements with enhanced degradative properties. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02854 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Sara Gallinetti Delphine Lemoine Caroline Öhman Mägi Google Sara Gallinetti Delphine Lemoine Caroline Öhman Mägi Google Scholar Sara Gallinetti Delphine Lemoine Caroline Öhman Mägi PubMed Sara Gallinetti Delphine Lemoine Caroline Öhman Mägi Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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