TY - JOUR A1 - Meininger, Susanne A1 - Blum, Carina A1 - Schamel, Martha A1 - Barralet, Jake E. A1 - Ignatius, Anita A1 - Gbureck, Uwe T1 - Phytic acid as alternative setting retarder enhanced biological performance of dicalcium phosphate cement in vitro JF - Scientific Reports N2 - Dicalcium phosphate cement preparation requires the addition of setting retarders to meet clinical requirements regarding handling time and processability. Previous studies have focused on the influence of different setting modifiers on material properties such as mechanical performance or injectability, while ignoring their influence on biological cement properties as they are used in low concentrations in the cement pastes and the occurrence of most compounds in human tissues. Here, analyses of both material and biological behavior were carried out on samples with common setting retardants (citric acid, sodium pyrophosphate, sulfuric acid) and novel (phytic acid). Cytocompatibility was evaluated by in vitro tests with osteoblastic (hFOB 1.19) and osteoclastic (RAW 264.7) cells. We found cytocompatibility was better for sodium pyrophosphate and phytic acid with a three-fold cell metabolic activity by WST-1 test, whereas samples set with citric acid showed reduced cell number as well as cell activity. The compressive strength (CS) of cements formed with phytic acid (CS = 13 MPa) were nearly equal to those formed with citric acid (CS = 15 MPa) and approximately threefold higher than for other setting retardants. Due to a proven cytocompatibility and high mechanical strength, phytic acid seems to be a candidate replacement setting retardant for dicalcium phosphate cements. KW - implants KW - biomedical materials KW - dicalcium phosphate cement KW - phytic acid Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-171047 VL - 7 IS - 558 ER - TY - JOUR A1 - Heilig, Philipp A1 - Sandner, Phoebe A1 - Jordan, Martin Cornelius A1 - Jakubietz, Rafael Gregor A1 - Meffert, Rainer Heribert A1 - Gbureck, Uwe A1 - Hoelscher-Doht, Stefanie T1 - Experimental drillable magnesium phosphate cement is a promising alternative to conventional bone cements JF - Materials N2 - Clinically used mineral bone cements lack high strength values, absorbability and drillability. Therefore, magnesium phosphate cements have recently received increasing attention as they unify a high mechanical performance with presumed degradation in vivo. To obtain a drillable cement formulation, farringtonite (Mg\(_3\)(PO\(_4\))\(_2\)) and magnesium oxide (MgO) were modified with the setting retardant phytic acid (C\(_6\)H\(_{18}\)O\(_{24}\)P\(_6\)). In a pre-testing series, 13 different compositions of magnesium phosphate cements were analyzed concentrating on the clinical demands for application. Of these 13 composites, two cement formulations with different phytic acid content (22.5 wt% and 25 wt%) were identified to meet clinical demands. Both formulations were evaluated in terms of setting time, injectability, compressive strength, screw pullout tests and biomechanical tests in a clinically relevant fracture model. The cements were used as bone filler of a metaphyseal bone defect alone, and in combination with screws drilled through the cement. Both formulations achieved a setting time of 5 min 30 s and an injectability of 100%. Compressive strength was shown to be ~12–13 MPa and the overall displacement of the reduced fracture was <2 mm with and without screws. Maximum load until reduced fracture failure was ~2600 N for the cements only and ~3800 N for the combination with screws. Two new compositions of magnesium phosphate cements revealed high strength in clinically relevant biomechanical test set-ups and add clinically desired characteristics to its strength such as injectability and drillability. KW - magnesium phosphate cement KW - phytic acid KW - inositol hexaphosphate KW - drillable bone cement KW - tibial head depression fracture KW - synbones KW - artificial bones KW - biomechanical evaluation KW - cyclic testing KW - load to failure testing Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236633 SN - 1996-1944 VL - 14 IS - 8 ER - TY - JOUR A1 - Brückner, Theresa A1 - Meininger, Markus A1 - Groll, Jürgen A1 - Kübler, Alexander C. A1 - Gbureck, Uwe T1 - Magnesium Phosphate Cement as Mineral Bone Adhesive JF - Materials N2 - Mineral bone cements were actually not developed for their application as bone-bonding agents, but as bone void fillers. In particular, calcium phosphate cements (CPC) are considered to be unsuitable for that application, particularly under moist conditions. Here, we showed the ex vivo ability of different magnesium phosphate cements (MPC) to adhere on bovine cortical bone substrates. The cements were obtained from a mixture of farringtonite (Mg\(_3\)(PO\(_4\))\(_2\)) with different amounts of phytic acid (C\(_6\)H\(_{18}\)O\(_{24}\)P\(_6\), inositol hexaphosphate, IP6), whereas cement setting occurred by a chelation reaction between Mg\(^{2+}\) ions and IP6. We were able to show that cements with 25% IP6 and a powder-to-liquid ratio (PLR) of 2.0 g/mL resulted in shear strengths of 0.81 ± 0.12 MPa on bone even after 7 d storage in aqueous conditions. The samples showed a mixed adhesive–cohesive failure with cement residues on the bone surface as indicated by scanning electron microscopy and energy-dispersive X-ray analysis. The presented material demonstrated appropriate bonding characteristics, which could enable a broadening of the mineral bone cements’ application field to bone adhesives KW - magnesium phosphate cement KW - phytic acid KW - bone adhesive Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-193052 SN - 1996-1944 VL - 12 IS - 23 ER -