122 research outputs found
α-tricalcium Phosphate Cement: "in Vitro" Cytotoxicity
No full textCalcium phosphate-based bioceramics have revolutionized orthopedic and dental repair of damaged parts of the bone system. Among these materials, calcium phosphate-based cements, with hydraulic setting, stand out due to their biocompatibility and in situ hardening, which allow easy manipulation and adaptation to the shape and dimensions of bone defects. An investigation was made of the in vitro cytotoxic effect of calcium phosphate cement based on α-tricalcium phosphate, immersed for different lengths of time in simulated body fluid (SBF), based on the ISO-10993 "Biological Evaluation of Medical Devices" standard. The culture medium was Chinese hamster ovary (CHO) cells in contact with diluted cement extracts. The results revealed that the calcium phosphate cement used was cytotoxic and that the material's cytotoxicity decreased the longer the cement was immersed in SBF. © 2002 Elsevier Science Ltd. All rights reserved.23920352042Gruninger, S.E., Siew, C., Chow, L.C., O'Young, A., Ts'ao, N.K., Brown, W.E., Evaluation of the biocompatibility of a new calcium-phosphate setting cement (1984) J Dent Res, pp. 63-200Yu, D., Wong, J., Matsuda, Y., Fox, J.L., Higuchi, W.I., Otsuka, M., Self-setting hydroxyapatite cement: A novel skeletal drug delivery system for antibiotics (1992) J Pharm Sci, 81 (6), pp. 529-531Driessens, F.C.M., Fernández, E., Ginebra, M.P., Boltong, M.G., Planell, J.A., Calcium phosphates and ceramic bone cements vs. acrylic cements (1997) Anal Quim Int Ed, 93, pp. S38-S43Monma, H., Goto, M., Kohmura, T., Effect of additives on hydration and hardness of tricalcium phosphate (1984) Gypsum lime, 188, pp. 11-16Ginebra, M.P., Fernández, E., Driessens, F.C.M., Planell, J.A., The effect of Na2HPO4 addition on the setting reaction kinetics of an α-TCP cement (1998) Biomaterials, 11, pp. 243-246Jenkins, R., Vries, J.L., (1971) An introduction to X-ray powder diffractometry, , Eindhoven, Holanda: N.V. Philips Gloeilampenfabrieken(1992) International standard: Biological evaluation of medical devices - Part 5: tests for cytotoxicity: in vitro methods, , ISO 10993-5Nakamura, A., Ikarashi, Y., Tshuchiya, T., Kaniwa, M., Radiation vulcanized natural rubber latex is not cytotoxic (1989) Proceedings of the International Symposium on Radiation Vulcanization of Natural Rubber Latex, pp. 79-87. , Japan Atomic Research Institute JAERI-M 89-228, Takasaki, JapanDriessens, F.C.M., Boltong, M.G., Bermudez, O., Planell, J., Efective formulations for the preparation of calcium phosphate bone cements (1994) J Mater Sci Mater Med, 5, pp. 164-170Fernández, E., Ginebra, M.P., Bermudez, O., Boltong, M.G., Driessens, F.C.M., Dimensional and thermal behaviour of calcium phosphate cements during setting compared to PMMA bone cements (1995) J Mater Sci Lett, 14, pp. 4-5Carrodéguas, R.G., Rigo, E.C., Oliveira, L.C., Santos, L.A., Boschi, A.O., Recubrimiento de hidroxiapatita sobre ceramica de titanato de bario BIOMAT'97 - Congresso Internacional de Biomateriales, , 4 de Maio/1997, Universidad de La Habana, CubaLi, P., Ohtswki, C., Kokubo, T., Apatite formation induced by silica gel in a simulated body fluid (1992) J Am Ceram Soc, 75, pp. 2094-2097Fresa, R., Constantini, A., Buri, A., Apatite formation on (2-x)CaO·x/3M2O3·2SiO2 glasses (M=La, Y0<x<0.6) in a simulated body fluid (1995) Biomaterials, 16, pp. 849-854Oliveira, J.M., Correia, R., Fernandes, M.H., Surface modifications of a glass and a glass-ceramic of the MgO-3CaO·P2O5-SiO2 system in a simulated body fluid (1995) Biomaterials, 16, pp. 849-854Santos, L.A., Oliveira, L.C., Rigo, E.C.S., Carrodéguas, R.G., Boschi, A.O., Arruda, A.C.F., Influence of polymeric additives on the mechanical properties of α-tricalcium phosphate cement (1999) Bone, 25 (2), pp. 99S-102SSantos, L.A., Oliveira, L.C., Rigo, E.C.S., Carrodéguas, R.G., Boschi, A.O., Arruda, A.C.F., Fiber reinforced calcium phosphate cement (2000) Artif Organs, 24 (3), pp. 212-216Carrodéguas, R.G., Santos, L.A., Rigo, E.C.S., Mondéjar, S.P., Arruda, A.C.F., Boschi, A.O., Improvement of mechanical strength of calcium phosphate cement by dual-setting principle J Mater Sci Mater Med, , submitted for publicationBermúdez, O., Boltong, M.G., Driessens, F.C.M., Planell, J.A., Development of an octacalcium phosphate cement (1994) J Mater Sci Mater Med, 5, pp. 144-146Tampieri, A., Celotti, G., Szontagh, F., Landi, E., Sintering and characterization of HA and TCP bioceramics with control of their strength and phase purity (1997) J Mater Sci Mater Med, 8, pp. 29-37Famery, R., Richard, N., Boch, P., Preparation of α- and β-tricalcium phosphate ceramics with and without magnesium addition (1994) Ceram Int, 20, pp. 327-336Fernández, E., Ginebra, M.P., Boltong, M.G., Verbeeck, R.M.H., Planell, J.A., Kinetic study of the setting reaction of a calcium phosphate bone cement (1996) J Biomed Mater Res, 32, pp. 367-374Ginebra, M.P., Fernández, E., De Maeyer, E.A.P., Verbeeck, R.M.H., Boltong, M.G., Ginebra, J., Driessens, F.C.M., Planell, J.A., Setting reaction and hardening of an apatitic calcium phosphate cement (1997) J Dent Res, 76 (4), pp. 905-912Driessens, F.C.M., Boltong, M.G., Bermúdez, O., Planell, J.A., Ginebra, M.P., Fernández, E., Effective formulations for the preparation of calcium phosphate bone cements (1994) J Mater Sci Mater Med, 5, pp. 164-170Bermúdez, O., Boltong, M.G., Driessens, F.C.M., Planell, J.A., Development of some calcium phosphate cements from combinations of α-TCP, MCPM and CaO (1994) J Mater Sci Mater Med, 5, pp. 160-163Fernández, E., Gil, J.F., Ginebra, M.P., Driessens, F.C.M., Planell, J.A., Production and characterization of new calcium phosphate bone cements in the CaHPO4-α-Ca3(PO4)2 system: pH, workability and setting times (1999) J Mater Sci Mater Med, 10, pp. 223-230Chow, L.C., Development of self-setting calcium phosphate cements (1991) J Ceram Soc Jpn (The Centennial Memorial Issue), 99 (10), pp. 954-964Ishikawa, K., Miyamoto, Y., Suzuki, K., Nagayama, M., Mechanism of inflamatory response to calcium phosphate cement (1998) J Dent Res, 1446, p. 812Miyamoto, Y., Ishikawa, K., Takechi, M., Toh, T., Yuasa, T., Nagayama, M., Suzuki, K., Histological and composicional evaluations of three types of calcium phosphate cements when implanted in subcutaneous tissue immediately after mixing (1999) J Biomed Mater Res, 48, pp. 36-4
The Effect of Lactic and Acetic Acid on the Formation of Artificial Caries Lesions
No full text Fluoride specifically adsorbed to hydroxyapatite reduces the rate of dissolution of hydroxyapatite. Since specific adsorption is a property which anions of all weak acids have in common, it is expected that the anions of lactic and acetic acid will be specifically adsorbed to hydroxyapatite too and in this way will cause a reduction in the rate of dissolution of hydroxyapatite. In order to investigate this, we used the experimental results from Featherstone and Rodgers (1981). Calculations of the rate of increase of the lesion depth in dental enamel per mmol. L -1 of the un-ionized acid revealed that lesion progress was pH-dependent and was lowest at that pH which corresponds with the pK-value of the relevant acid. It is concluded that the anions of lactic and acetic acid are specifically adsorbed to the enamel mineral and in this way reduce the rate of dissolution of the mineral. This suggests that a description of the development of an artificial caries lesion in mathematical terms should include the effect on the rate of dissolution of the mineral of specific adsorption of the relevant acid anions to the mineral. </jats:p
On the Static Creep of Dental Amalgam
No full text A new equation is proposed for the description of the static creep of dental amalgam. It is satisfactory for a wide range of stresses and strain rates in static creep experiments during steady state. The hypothesis was confirmed that creep of dental amalgam is determined by the low melting phases. </jats:p
Fiber Reinforced Calcium Phosphate Cement
No full textThe term calcium phosphate cement was introduced by Gruninger et al. (1). This type of cement can be prepared by reacting a calcium phosphate salt with an aqueous solution, which causes it to set by the crossing of the precipitated crystals. These cements offer a series of advantages that allow their use as grafts and substitutes of damaged parts of the bone system. However, these cements have low mechanical strength compared to human bones. This work studied the influence of the use of polyamide fibers in the mechanical properties of a calcium phosphate cement based on α-tricalcium phosphate as well as the mechanisms involved in the increase of mechanical strength. The results demonstrate the feasibility of the use of polymeric fibers to increase mechanical strength and the need for coupling agents for the effective performance of the fibers as reinforcement in these materials.243212216Gruninger, S.E., Siew, C., Chow, L.C., O'Young, A., Ts'ao, N.K., Brown, W.E., Evaluation of the biocompatibility of a new calcium phosphate setting cement (1984) J Dent Res, 63, pp. 63-200Yu, D., Wong, J., Matsuda, Y., Fox, J.L., Higuchi, W.I., Otsuka, M., Self-setting hydroxyapatite cement: A novel skeletal drug delivery system for antibiotics (1992) J Pharm Sci, 81 (6), pp. 529-531Driessens, F.C.M., Fernández, E., Ginebra, M.P., Boltong, M.G., Planell, J.A., Calcium phosphates and ceramic bone cements vs. acrylic cements (1997) Anal Quim Int Ed, 93, pp. S38-S43Monma, H., Goto, M., Kohmura, T., Effect of additives on hydration and hardness of tricalcium phosphate (1984) Gypsum and Lime, 188, pp. 11-16Bermúdez, O., Boltong, M.G., Driessens, F.C.M., Planell, J.A., Development of an octacalcium phosphate cement (1994) J Mater Sci Mater Med, 5, pp. 144-146Tampieri, A., Celotti, G., Szontagh, F., Landi, E., Sintering and characterization of HA and TCP bioceramics with control of their strength and phase purity (1997) J Mater Sci Mater Med, 8, pp. 29-37Famery, R., Richard, N., Boch, P., Preparation of α- and β-tri-calcium phosphate ceramics with and without magnesium addition (1994) Ceram Int, 20, pp. 327-336Fernández, E., Ginebra, M.P., Boltong, M.G., Verbeeck, R.M.H., Planell, J.A., Kinetic study of the setting reaction of a calcium phosphate bone cement (1996) J Biomed Mater Res, 32, pp. 367-374Ginebra, M.P., Fernández, E., De Maeyer, E.A.P., Verbeeck, R.M.H., Boltong, M.G., Ginebra, J., Driessens, F.C.M., Planell, J.A., Setting reaction and hardening of an apatitic calcium phosphate cement (1997) J Dent Res, 76 (4), pp. 905-912Driessens, F.C.M., Boltong, M.G., Bermudez, O., Planell, J.A., Effective formulations for the preparation of calcium phosphate bone cements (1994) J Mater Sci Mater Med, 5, pp. 164-170Fernández, E., Ginebra, M.P., Bermudez, O., Boltong, M.G., Driessens, F.C.M., Dimensional and thermal behavior of calcium phosphate cements during setting compared to PMMA bone cements (1995) J Mater Sci Lett, 14, pp. 4-5Beaudoin, J.J., (1990) Handbook of Fiber-Reinforced Concrete, , Park Ridge, NJ: Noyes PublicationsGarcía Carrodeguas, R., Silva Rigo, E., Dos Santos, L.A., De Oliveira, L.C., Boschi, A.O., Recubrimiento de hidroxiapatita sobre cerámica de BaTiO3 (1997) 1st Congreso Iberoamericano de Biomateriales BIOMAT'97, , La Habana, MayRigo, E.C.S., Oliveira, L.C., Boschi, A.O., (1996) Efeito das Condições de Precipitação Sobre as Característica Físico-Química dos Compostas do Sistema Fosfato de Cálcio, pp. 9-10. , III Encontre Nacional de Biomateriais, São Paulo, Brazil, MayOyabu, M., Japanese Patent No. 48-19,489, 197
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