TY  - JOUR
A1  - Boehm, Anne
A1  - Meininger, Susanne
A1  - Tesch, Annemarie
A1  - Gbureck, Uwe
A1  - Müller, Frank A.
T1  - The mechanical properties of biocompatible apatite bone cement reinforced with chemically activated carbon fibers
JF  - Materials
N2  - Calcium phosphate cement (CPC) is a well-established bone replacement material in dentistry and orthopedics. CPC mimics the physicochemical properties of natural bone and therefore shows excellent in vivo behavior. However, due to their brittleness, the application of CPC implants is limited to non-load bearing areas. Generally, the fiber-reinforcement of ceramic materials enhances fracture resistance, but simultaneously reduces the strength of the composite. Combining strong C-fiber reinforcement with a hydroxyapatite to form a CPC with a chemical modification of the fiber surface allowed us to adjust the fiber–matrix interface and consequently the fracture behavior. Thus, we could demonstrate enhanced mechanical properties of CPC in terms of bending strength and work of fracture to a strain of 5% (WOF5). Hereby, the strength increased by a factor of four from 9.2 ± 1.7 to 38.4 ± 1.7 MPa. Simultaneously, the WOF5 increased from 0.02 ± 0.004 to 2.0 ± 0.6 kJ∙m−2, when utilizing an aqua regia/CaCl2 pretreatment. The cell proliferation and activity of MG63 osteoblast-like cells as biocompatibility markers were not affected by fiber addition nor by fiber treatment. CPC reinforced with chemically activated C-fibers is a promising bone replacement material for load-bearing applications.
KW  - calcium phosphate cement
KW  - damage tolerant cement
KW  - carbon fiber reinforcement
KW  - interface control
KW  - fiber–matrix interaction
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197808
SN  - 1996-1944
VL  - 11
IS  - 2
ER  - 
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  -