Fabrication of low‐crystallinity hydroxyapatite foam based on the setting reaction of α‐tricalcium phosphate foam

Karashima, Satoshi; Takeuchi, Akari; Matsuya, Shigeki; Udoh, K.; Koyano, Kiyoshi; Ishikawa, Kunio

doi:10.1002/jbm.a.31904

Cited by 37 publications

(27 citation statements)

References 23 publications

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“…In this study, NH3 solution was preferred to other strong basic media to avoid any extra ionic substitution in apatite structure. The incorporation of NH 4 + ion (ionic radius: 1.45 Å) in the apatite structure (ionic radius of Ca + : 1.00 Å) seems to be difficult due to its large ionic radius 8) . Therefore, a calcium-deficient apatite free of cationic substitution can be obtained as shown by the Ca/P ratio measured in this study.…”

Section: Discussionmentioning

confidence: 99%

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Effect of precursor^|^apos;s solubility on the mechanical property of hydroxyapatite formed by dissolution-precipitation reaction of tricalcium phosphate

et al. 2012

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INTRODUCTIONIn the 1970's, Aoki et al. found that stoichiometric hydroxyapatite (HAp; Ca10(PO4)6(OH)2) can be sintered and that it showed excellent tissue response and good osteoconductivity, i.e., the existing bone is bonded with sintered HAp when implanted adjacent to the bone 1,2) . Although sintered HAp showed stability and relatively high mechanical strength, however, sintered HAp cannot be resorbed when implanted since sintered HAp demonstrates high crystallinity due to its crystal growth enhanced by heating at high temperature. Therefore, in recent year, fabrication of low crystalline HAp or carbonate apatite (CO 3Ap) which has similar crystallinity and chemical composition to human bone has been paid much attention. Sintering method cannot be adopted for the fabrication of low crystalline HAp and CO 3Ap since the heating induces crystal growth of HAp and decomposition of CO3Ap.An alternative method to fabricate low crystalline HAp or CO 3Ap is the phase transformation reaction using thermodynamically unstable precursor or the so-called dissolution-precipitation reaction. Our reserach group has been reported that low crystalline HAp block and HAp foam were prepared using gypsum (CaSO 4•2H2O) block and alpha tricalcium phosphate (α-TCP) foam as the precursor 3,4) . For the formation of HAp block, gypsum block was immersed in (NH4)2HPO4 and treated at 60°C, 80°C and 100°C for a prescribed period. While for the formation of HAp foam, the α-TCP foam was immersed in distilled water at 37°C for 24 h or subjected to hydrothermal treatment at 100°C and 200°C for 24 h for the dissolution-precipitation reaction to occur. Also CO 3Ap block and CO3Ap foam can be prepared by phase transformation in dissolution-precipitation reaction using CaCO 3 (calcite) block, α-TCP and calcite foam. Calcite block was immersed in Na2HPO4 solution and heated at 60°C for various periods up to 14 days while α-TCP foam was immersed in (NH 4)2CO3 solution at 200°C for 24 h 5,6) . For the treatment of calcite foam, the calcite foam was immersed in Na2HPO4 solution at 60°C for 2 weeks 7) . In the previous studies, it was found that the mechanical strength of low crystalline HAp or CO 3Ap block or foam were different up to the precursor and condition used for the dissolution-precipitation reaction. For example, diametral tensile strength (DTS) of CO 3Ap block using calcite block as a precursor was 5 MPa whereas DTS value of CO 3Ap block using gypsum as the precursor was 2 MPa. Compressive strength of CO3Ap foam obtained using calcite foam as a precursor was approximately 26 kPa while that of CO 3Ap foam using α-TCP foam as precursor was approximately 6 kPa. Of course these differences in mechanical strength are reasonable since chemical composition, densities of the precursors, treatment conditions such as temperature, type of solution and solution pH were different. Therefore, factors that affect the mechanical strength should be clarified.As an initial step to understand the factors that affect the mechanical strength, effect of precursor...

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Section: Discussionmentioning

confidence: 99%

“…Our reserach group has been reported that low crystalline HAp block and HAp foam were prepared using gypsum (CaSO 4•2H2O) block and alpha tricalcium phosphate (α-TCP) foam as the precursor 3,4) . For the formation of HAp block, gypsum block was immersed in (NH4)2HPO4 and treated at 60°C, 80°C and 100°C for a prescribed period.…”

Section: Introductionmentioning

confidence: 99%

Effect of precursor^|^apos;s solubility on the mechanical property of hydroxyapatite formed by dissolution-precipitation reaction of tricalcium phosphate

et al. 2012

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“…The artificial bones usually require post-fabrication sintering process to increase their mechanical properties, which causes contraction in size and often decreases biodegradability, as well as shape adjustment during surgery [110][111][112][113]. Therefore, there is a need for novel artificial bones that have better shape compatibility to deformities, appropriate mechanical strength without the post-fabrication sintering, and biodegradability.…”

Section: Scaffolds For Bone Tissue Engineeringmentioning

confidence: 99%

Current Progress on Tissue Engineering of Bone and Cartilage

2012

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“…One of the key advantages of the BC method is that coating can be performed at room temperature. It has been reported that apatite sintered at lower temperature shows better osteoconductivity 12) . Therefore, BC may allow fabrication of apatite-coated Ti implants with higher osteoconductivity.…”

Section: Introductionmentioning

confidence: 99%

Comparison of apatite-coated titanium prepared by blast coating and flame spray methods —Evaluation using simulated body fluid and initial histological study —

et al. 2011

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It has previously been demonstrated that apatite may be coated on the surface of titanium (Ti) at room temperature when the titanium is blasted with apatite powder. This method is known as the blast coating (BC) method. In this study, the osteoconductivity and tissue response to Ti implants blast-coated with apatite (BC implants) were evaluated using apatite-coated Ti implants produced using the flame spraying (FS) method (FS implants) and pure Ti implants as a control. Initial evaluation using simulated body fluid demonstrated higher osteoconductivity in BC implants than in FS implants. Therefore, specimens were implanted in rat tibias for 1, 3 and 6 weeks. At one week after implantation, BC implants showed much higher bone contact ratio when compared with FS implants; the bone contact ratio of BC implants was 75.7%, while the FS and pure Ti implants had ratios of 30.8% and 5.5%, respectively. The difference in bone contact ratio between BC and FS implants decreased with implantation time and the ratios were equal after 6 weeks. In conclusion, BC implants show higher osteoconductivity than FS implants, and thus BC implants are beneficial for early fixation of implants to bone tissue.

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Fabrication of low‐crystallinity hydroxyapatite foam based on the setting reaction of α‐tricalcium phosphate foam

Cited by 37 publications

References 23 publications

Effect of precursor^|^apos;s solubility on the mechanical property of hydroxyapatite formed by dissolution-precipitation reaction of tricalcium phosphate

Effect of precursor^|^apos;s solubility on the mechanical property of hydroxyapatite formed by dissolution-precipitation reaction of tricalcium phosphate

Current Progress on Tissue Engineering of Bone and Cartilage

Comparison of apatite-coated titanium prepared by blast coating and flame spray methods —Evaluation using simulated body fluid and initial histological study —

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