Mechanische Festigkeit und Porosität von Calciumphosphat-Zementen

Gbureck, Uwe; Barralet, J.E.; Grover, Liam M.; Hofmann, Matthias J.; Thulĺ, R.

doi:10.1515/biomat.2003.4.4.258

Cited by 11 publications

(12 citation statements)

References 14 publications

(15 reference statements)

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“…Factors influencing strength of printed samples were the acid concentration used for printing, which led to both a higher degree of conversion to brushite and a higher density and lower porosity of the matrix, respectively. Both factors are well known to affect the mechanical performance of calcium phosphate materials, e.g., a linear relation of cement strength with the degree of conversion in cement matrices has been reported [19] and an exponential relationship between the compressive strength of cement materials and their porosity is well known. [20] Strengths found in this study were up to 22 MPa under compressive load, which are higher than those commonly obtained for brushite cement mixtures based on TCP or HA/phosphoric acid solutions.…”

Section: Discussionmentioning

confidence: 99%

Resorbable Dicalcium Phosphate Bone Substitutes Prepared by 3D Powder Printing

Gbureck

Hölzel

Klammert

et al. 2007

Adv Funct Materials

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222

204

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Bioceramic bone substitutes with programmed architecture were manufactured at room temperature in this study using a novel 3D printing process that combined 3D powder printing with calcium phosphate cement chemistry. During printing, biphasic α/β‐tricalcium phosphate (Ca3(PO4)2, TCP) powder reacted with a liquid component consisting of phosphoric acid solution to form a matrix of dicalcium phosphate dihydrate (CaHPO4·H2O, DCPD, brushite) and unreacted TCP. Printed samples showed compressive strengths between 0.9–8.7 MPa after printing depending on the acid concentration. A further strength improvement to a maximum of 22 MPa could be obtained by additional hardening of the samples in phosphoric acid for three one minute washes. After this treatment, the samples mainly consisted of brushite with minor phases of unreacted TCP and a lesser amount of dicalcium phosphate anhydrate (CaHPO4, DCPA, monetite). Hydrothermal conversion of brushite to DCPA resulted in an increase of porosity of approximately 13 % and a decrease of strength to 15 MPa, however the resorption rate in vivo was increased as demonstrated after intramuscular implantation over 56 weeks. Major advantages compared with commonly used sintering techniques are the low processing temperature, which enables the fabrication of thermally instable and degradable matrices of secondary calcium phosphates.

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Section: Discussionmentioning

confidence: 99%

Resorbable Dicalcium Phosphate Bone Substitutes Prepared by 3D Powder Printing

Gbureck

Hölzel

Klammert

et al. 2007

Adv Funct Materials

Self Cite

222

204

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“…These results are in good agreement with those of a previous report that ¢-TCP is transformed into calcium-deficient HAp (CDAp) by a mechanochemical reaction. 26) In other words, the HAp phase obtained from ball-milled ¢-TCP powders is CDAp. Tenhuisen et al reported that the CDAp is biocompatible and bioresorbable.…”

Section: Mechanical Property Of the Ip6/¢-tcp Cement Specimensmentioning

confidence: 99%

Fabrication of novel bioresorbable .BETA.-tricalcium phosphate cement on the basis of chelate-setting mechanism of inositol phosphate and its evaluation

Takahashi

Konishi

Nishiyama

et al. 2011

J. Ceram. Soc. Japan

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We have developed novel bioresorbable ¢-tricalcium phosphate (¢-TCP) cements on the basis of chelate-setting mechanism of inositol phosphate (IP6). The starting cement powders (IP6/¢-TCP powders) were prepared by surface-modifying ¢-TCP particles with IP6. The cement specimen was fabricated by mixing the IP6/¢-TCP powder in pure water at desired powder/ liquid ratios, and examined the effects of powder properties of the IP6/¢-TCP powder on the mechanical strength (compressive strength) of the cement specimens. We focused on the crystalline phase, particle size, specific surface area (SSA), and crystallite size among powder properties. The crystalline phase of resulting cement specimen was ¢-TCP single phase or mixture of ¢-TCP and calcium-deficient apatite (CDAp). The ¢-TCP cement with compressive strength of 13 MPa was fabricated from the finelyground ¢-TCP powders prepared by ball-milling commercially-available ¢-TCP powder for 4 h using zirconia beads with 10 mm in diameter. Meanwhile, the ¢-TCP/CDAp biphasic cement had maximum compressive strength of about 23 MPa among the examined cement specimens, it was fabricated from the ball-milled commercially-available ¢-TCP powder for 3 h using zirconia beads with 10 mm in diameter, and then for 3 h using zirconia beads with 2 mm in diameter. In order to make the determining factors of the compressive strength clear, we examined the relationship between powder properties (particle size, SSA and crystallite size) and compressive strength. The strength of the IP6/¢-TCP cement was not dependent on the particle size of the IP6/¢-TCP powder; meanwhile, the strength was enhanced with increasing SSA and decreasing crystallite size. Thus, the IP6/¢-TCP powder with higher SSA and smaller crystallite size may be useful in the fabrication of chelate-setting ¢-TCP cement with enhanced mechanical properties.

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“…It is known that ball-milling decreases the crystallinity of ¢-TCP powders. 16) This phenomenon suggests that mechanochemical energy converts ¢-TCP from a crystalline to an amorphous phase. Table 1 lists various properties of the prepared powders, such as median particle size, amount of IP6 adsorbed and surface zeta potential.…”

Section: Characterization Of Starting Powdersmentioning

confidence: 99%

Evaluation of resistance to fragmentation of injectable calcium-phosphate cement paste using X-ray microcomputed tomography

Nagata

Fujioka

Konishi

et al. 2017

J. Ceram. Soc. Japan

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Property of resistance to fragmentation of injectable calcium-phosphate cement (CPC) pastes was evaluated. CPC pastes are widely used as bone fillers due to their biocompatibility and osteoconductivity. However, the potential for fractures due to the formation of voids and cracks in the CPC, called "fragmentation," reduces the biomechanical strength of CPCs. To develop new CPCs that do not exhibit fragmentation, a method for assessing the presence or absence of fragmentation is required. For in vitro evaluation of the fragmentation resistance, the internal structure of cement specimens allowed to stand in pure water or blood was observed using X-ray micro-computed tomography (X-ray¯-CT) method. In the case of cement specimens derived from commercially-available ¢-tricalcium phosphate powder ball milled and surface modified in 3,000 ppm inositol phosphate solution, no cracks or voids in the internal structure were observed in samples allowed to set in either pure water or blood. For in vivo verification of the fragmentation resistance, the same CPC pastes were implanted into pig thigh muscle and tibiae for 4 and 24 weeks, respectively. The implanted CPC specimens formed a lump without internal voids or cracks. These data showed that the CPC pastes with the fragmentation resistance both in vitro and in vivo and are thus unlikely to generate fractures. Furthermore, the evaluation method using X-ray¯-CT could enables rapid and simple verification of the fragmentation resistance of the injectable CPC pastes. To our knowledge, this is the first report of the use of this method to evaluate resistance to fragmentation of CPC pastes. Furthermore, because of its simplicity and ease of use, the X-ray¯-CT method shows promise as a gold standard.

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Mechanische Festigkeit und Porosität von Calciumphosphat-Zementen

Cited by 11 publications

References 14 publications

Resorbable Dicalcium Phosphate Bone Substitutes Prepared by 3D Powder Printing

Resorbable Dicalcium Phosphate Bone Substitutes Prepared by 3D Powder Printing

Fabrication of novel bioresorbable .BETA.-tricalcium phosphate cement on the basis of chelate-setting mechanism of inositol phosphate and its evaluation

Evaluation of resistance to fragmentation of injectable calcium-phosphate cement paste using X-ray microcomputed tomography

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