Papers by Keyword: Tricalcium Phosphate

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Authors: M. Motisuke, R. García Carrodeguas, Cecília A.C. Zavaglia
Abstract: On this study the influence of silicon dopping on the properties of the final calcium phosphate cement were analysed and compared to the ones of the conventional Si and Mg-free α-TCP cement. In spite of silicon doping, Si-α-TCP calcination temperature (1400°C) was higher than the one used for conventional α-TCP (1300°C) as a result of Mg contamination on the commercial precursor used on the Si-α-TCP synthesis. Because of the high temperature used, Si-α-TCP sample was difficult to mill. Even after 1 week milling, the particle size achieved was 12µm while Si-free α-TCP reached 7.7µm. Consequently, the reactivity of both powders was different. In conclusion, the properties of Si-α-TCP cement were not satisfactory for clinical application. In order to do it so, it is essential to enhance the powder reactivity by reducing Mg contamination, lowering the sintering temperature and reducing the particle size to, then, achieve the desired reactivity and compressive strength.
201
Authors: Sergey V. Dorozhkin, Elena I. Dorozhkina, Faik N. Oktar, S. Salman
Abstract: A simplified preparation method of silicon-substituted calcium phosphates with a very high yield (close to 100%) has been elaborated, according to the principles of Green Chemistry. The technique consists of mixing of crystals of calcium nitrate and ammonium dihydrogen phosphate in the desired proportions, following by addition of the necessary amount of a silicon-containing compound. The homogenous mixture is sintered between 900 and 1200°C. Either a siliconcontaining hydroxyapatite (Si-HA) or a silicon-stabilized tricalcium phosphate (Si-αTCP) can be synthesized, depending on the Ca/P, Ca/(P+Si) and Si/P molar ratios.
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Authors: Ei Yamamoto, Nobuhiro Kato, Hiroaki Nishikawa, Masanobu Kusunoki, Takashi Hayami, Kazushi Yoshikawa, Shigeki Hontsu
Abstract: Tooth enamel cannot be reconstructed once it is destroyed immoderately. Hydroxyapatite (HAp) thin sheet can potentially be used for a novel dental biomaterial to repair the enamel. Using a pulsed laser deposition (PLD) method, we have successfully created a flexible HAp sheet of less than a few micrometers in thickness. Due to its flexibility, the HAp sheet is tightly adhered on curved surfaces at the target site. In the present study, we newly developed double-layered sheets composed of HAp film coated with tricalcium phosphate (TCP) thin layer. The HAp/TCP sheet was adhered to the extracted human teeth using a calcium phosphate solution for 3 days. The adhesive strength between the HAp/TCP sheet and tooth enamel was evaluated by quasi-static tensile tests. Moreover, the interface structure between them was observed by a scanning electron microscopy. As a result of the mechanical evaluation, the adhesive strength was greater than approximately 2.5 MPa. The electron microscopic observation revealed that the sheet was partially fused with the enamel. These findings suggest the possibility that enamel defects are repaired using the HAp/TCP sheet for a short duration.
522
Authors: Toshimasa Uemura, J. Dong, Takafumi Yoshikawa, Y. Hakamatsuka, H. Irie, Hisahiro Inoue, Tetsuya Tateishi
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Authors: Xin Long Wang, Hong Song Fan, Xing Dong Zhang
Abstract: b-tricalcium phosphate(TCP, Ca3(PO4)2) ceramics are preferred as a bioceramics because of its chemical stability and reasonable degradation rate in vivo, but it is difficult to obtain b-TCP ceramics with high compressive strength at lower temperature than that of phase transition to a-TCP. In this study, the sintering behavior of TCP, Ca2P2O7-doped TCP, and CaCO3-doped TCP in the range of 2wt%~5wt% were investigated respectively. Phase transition of pure TCP took place between 1100°C to 1150°C, and pure b-TCP ceramics could achieve a compressive strength of only 3MPa. However, calcium pyrophosphate (CPP, Ca2P2O7) additive prevented the transformation of b-TCP to a-TCP, but the second phase of CPP was observed in the resultant ceramics. Phase transition of TCP ceramics by addition of both CPP and calcium carbonate (CC, CaCO3) took place between 1200°C to 1250°C and the resultant TCP ceramics had few impurity of CPP. By adding CPP and CC to TCP, final ceramics with compressive strength over 12MPa could be obtained when sintered at 1200°C for 2hrs.
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Authors: Yasutaka Yamada, Atsuo Ito, Hiroko Kojima, Masataka Sakane, Shumpei Miyakawa, Toshimasa Uemura, Racquel Z. LeGeros
Abstract: Osteoclasts isolated from rabbits were cultured on zinc-containing tricalcium phosphate (ZnTCP) disks with zinc contents of 0.316 and 0.633 wt%, and on β-tricalcium phosphate (TCP) disks with nearly identical porosities, grain sizes and surface roughnesses. ZnTCPs directly suppressed the resorption activity of mature osteoclasts by enhancing apoptosis. We hypothesized that resorbing osteoclasts attached to ZnTCP locally accumulate zinc ions within the space defined by the clear zone during resorption, which in turn leads to apoptosis induction, even though the change in chemical composition of the culture medium is very small.
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Authors: Chan Wai Chan, Ling Qin, K.M. Lee, H.Y. Yeung, Yun Yu Hu, K.H.K. Wong, R.C.L. Yip, Jack C.Y. Cheng
Abstract: Grafting of autologous iliac crest and decortication approach in posterior spinal fusion surgery has been the “gold standard”. However, the limited source of autograft has prompted extensive research into bone substitute and biological enhancement of the fusion mass. In this study, the application of stem cell therapy by tissue engineering method was investigated to enhance posterior spinal fusion with -tricalcium phosphate ceramics in rabbit model. Rabbit bone marrow derived mesenchymal stem cells were aspirated from trochanter region of proximal femur. The mesenchymal stem cells were grown and directed to differentiate into osteogenic cells by osteogenic supplement (ascorbic acid, -glycerophosphate and dexamethasone) in basal medium (10% FBS in DMEM). The osteogenic cells were seeded on tricalcium phosphate ceramics for one day (MSC group, n=6). The cell-ceramics composite was implanted onto autologous L5 and L6 transverse processes with decortication approach in posterior spinal fusion. The cell free ceramics acts as control (Control group, n=6) and iliac crest autograft as positive control (Autograft group). The spinal segments were harvested at week 7 post-operation. Manual palpation was performed with spinal segments to assess any movement of L5-L6 vertebral joint. The stiffness of the joint was considered as solid fusion. The specimens then were fixed by formalin and transferred to 70% ethanol. The BMC and volume of fusion transverse processes of L5 and L6 was measured by peripheral quantitative computed tomography. In manual palpation, 50% solid fusion was found in MSC group, 60% in autograft group but none in control group. Moreover, the BMC of L5 and L6 transverse processes in MSC group was greater than autograft and control group (45%, 40% respectively, p<0.01). The volume of transverse processes in MSC group was greater than autograft by 45% (p<0.01) and control group by 26% (p<0.05). In conclusion, the mesenchymal stem cells derived osteogenic cells augmented spinal fusion and bone mineralization.
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Authors: Wei Qi Yan, Xin Huang, Xiao Chun Zhong, Shun Dong Miao, Wen Jian Weng, Kui Cheng
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Authors: Jae Hyup Lee, Hyun Seung Ryu, Jun Hyuk Seo, Hwan Kim, Kug Sun Hong, Bong-Soon Chang, Choon Ki Lee
Abstract: The purpose of our study is to compare the biodegradation and osteoconduction between CaO-SiO2-B2O3 glass-ceramics(CS10B) and hydroxyapatite(HA), tricalcium phosphate(TCP). Porous CS10B implants were prepared by polymer sponge method. Single-level posterolateral spinal fusions were performed on thirty rabbits. The animals were divided into three groups by implant material: HA, TCP and CS10B. Radiographs checked every two weeks. All animals were sacrificed 12 weeks after surgery. The proportion of the area occupied by ceramics in final radiography on the initial radiography was calculated. Uniaxial tensile strength was measured on 7 cases in each group. The proportion of the area of HA(88.7%±16.1) was significantly higher than those of the others(p<0.05), and the proportion of the area of CS10B(28.2%±9.3) was significantly lower than those of HA and TCP(37%±9.6)(p<0.05). The mean values of tensile strength of the HA(191.4±33.5 N) and CS10B(182.7±19.9 N) were significantly higher(p<0.05) than those of the TCP(141.1±28.2 N). CS10B showed the tensile strength of fusion masses similar to those of the HA, however, more rapid biodegradation than HA and TCP. These findings suggest that CS10B grafts have the possibility as a bone graft substitute.
905
Authors: G. Daculsi
Abstract: The development of calcium phosphate ceramics and other related biomaterials for bone graft involved a better control of the process of biomaterials resorption and bone substitution. The biphasic calcium phosphate ceramics (BCP) concept is determined by an optimum balance of the more stable phase of HA and more soluble TCP. The material is soluble and gradually dissolves in the body, seeding new bone formation as it releases calcium and phosphate ions into the biological medium The main attractive feature of BCP ceramic is their ability to form a direct bond with the host bone resulting in a strong interface. The formation of this dynamic interface is the result of a sequence of events involving interaction with cells; formation of carbonate hydroxyapatite CHA (similar to bone mineral) by dissolution/precipitation processes. At the present time, BCP is commercially available in blocks, particulates, customized design. The need of material for Minimal Invasive Surgery (MIS) induced the development of a concept of granules combination with polymer or calcium phosphate cement for injectable/mouldable bone substitutes. Four types of injectable/mouldable bone substitutes have been developed by INSERM Nantes University.
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