Calcium phosphate cement

Polymeric Calcium Phosphate Cements. Aqueous solutions of polymers such as poly(acryHc acid), poly(vinyl alcohol), gelatin, etc, and/or autopolymerizable monomer systems, eg, 2-hydroxyethyl methacrylate, glycerol dimethacrylate, calcium dimethacrylate, etc, have been used as Hquid vehicles (41,42,76) for the self-setting calcium phosphate cement derived from tetracalcium phosphate and dicalcium phosphate [7757-93-9J. 

Calcium phosphate cements have been developed during the last two decades. They are suitable for the repair and reconstruction of bone they adapt immediately to the bone cavity and permit subsequent good osteointe-gration. 

Foam cement is a special class of lightweight cement. The gas content of foamed cement can be up to 75% by volume. The stability of the foam is achieved by the addition of surfactants, as shown in Table 10-9. A typical foamed cement composition is made from a hydraulic cement, an aqueous rubber latex in an amount up to 45% by weight of the hydraulic cement, a latex stabilizer, a defoaming agent, a gas, a foaming agent, and a foam stabilizer [359,362]. Foamed high-temperature applications are based on calcium phosphate cement [257]. 

M. L. Allan and L. E. Kukacka. Calcium phosphate cements for lost circulation control in geothermal. Geothermics, 24(2) 269-282, April 1995. 

Y. Fukase, E.D. Eanes, S. Takagi, L.C. Chow, W.E. Brown, Setting reaction and compressive strengths of calcium phosphate cements, J. Dent. Res. 69 (1990) 1852-1856. 

A.A. Mirtchi, J. Lemaitre, E. Munting, Calcium phosphate cements Effect of fluorides on the setting and hardening of beta-tricalcium phosphate-dicalcium phosphate-calcite cements. Biomaterials 12 (1991) 505-510. 

X. Miao, Y. Hu, J. Liu, A.P. Wong, Porous calcium phosphate ceramics prepared by coating polyurethane foams with calcium phosphate cements. Mater. Lett. 58 (2004) 397 02. 

Yuan, H., Li, Y., Kurashina, K., and Zhang, X., Host tissue response of calcium phosphate cement, in Biomedical Materials Research in the Far East (III). (X. Zhang and Y. Ikada, Eds.), Kobunshi Kankokai, Kyoto, Japan, 1997e, p. 116-117. 

Calcium Phosphate Cements from Calcium Silicates and Aluminates 147... 

CALCIUM PHOSPHATE CEMENTS FROM CALCIUM SILICATES AND ALUMINATES... 

CALCIUM PHOSPHATE CEMENTS WITH BIOMEDICAL APPLICATIONS... 

The major interest in calcium phosphate cements has always been in their potential for biomedical applications. This is because bone contains hydroxyapatite (Ca5(P04)30H), a calcium phosphate mineral. Any material that could be used to bond bone or produce an artificial graft should contain this mineral for compatibility. In fact, much of the research in producing calcium phosphate-based cements or sintered ceramics was motivated by their biomedical applications. We will discuss applications of calcium phosphate cements in detail in Chapter 18. This section describes their materials development. 

Calcium Phosphate Cements with Biomedical Applications... 

Calcium oxide is the main ingredient in conventional portland cements. Since limestone is the most abundant mineral in nature, it has been easy to produce portland cement at a low cost. The high solubility of calcium oxide makes it difficult to produce phosphate-based cements. However, calcium oxide can be converted to compounds such as silicates, aluminates, or even hydrophosphates, which then can be used in an acid-base reaction with phosphate, forming CBPCs. The cost of phosphates and conversion to the correct mineral forms add to the manufacturing cost, and hence calcium phosphate cements are more expensive than conventional cements. For this reason, their use has been largely limited to dental and other biomedical applications. Calcium phosphate cements have found application as structural materials, but only when wollastonite is used as an admixture in magnesium phosphate cements. Because calcium phosphates are also bone minerals, they are indispensable in biomaterial applications and hence form a class of useful CBPCs that cannot be substituted by any other. 

C.E. Semler, A quick-setting wollastonite phosphate cement, Am. Ceram. Soc. Bull, 55 (1976) 983-988. T. Sugama and M. Allan, Calcium phosphate cements prepared by acid-base reaction, J. Am. Ceram. Soc., 75 [8] (1992) 2076-2087. 

T. Sugama, N.R. Carciello, T.M. Nayberg, and L.E. Brothers, Mullite microsphere-filled lightweight calcium phosphate cement slurries for geothermal wells setting and properties, Cem. Cone. Res., 25 [6] (1995) 1305-1310. 

L. C. Chow, S. Hirayama, S. Takagi, and E. Perry, Diametral tensile strength and compressive strength of a calcium phosphate cement effect of applied pressure, J. Biomed. Mater., S3 [5] (2000) 511-517. 

The biocompatible CBPC development has occurred only in the last few years, and the recent trend has been to evaluate them as biocompatible ceramics. After all, biological systems form bone and dentine at room temperature, and it is natural to expect that biocompatible ceramics should also be formed at ambient temperature, preferably in a biological environment when placed in a body as a paste. CBPCs allow such placement. We have discussed such calcium phosphate-based cements in Chapter 13. Calcium-based CBPCs, especially those constituting hydroxyapatite (HAP), are a natural choice. HAP is a primary mineral in bone [3], and hence calcium phosphate cements can mimic natural bone. Some of these ceramics with tailored composition and microstructure are already in use, yet there is ample room for improvement. This Chapter focuses on the most recent biocompatible CBPCs and their testing in a biological environment. To understand biocompatible material and its biological environment, it is first necessary to understand the structure of bone and how it is formed. 

Miyamoto, Y, Ishikawa, K., Takechi, M., Toh, T., Ynasa, T., Nagayama, M., and Suzuki, K., Basic properties of calcium phosphate cement containing atelocoUagen in its liquid or powder phases. Biomaterials, 19, 707, 1998. 

Kazemzadeh, A. (2012) Development of strong and bioactive calcium phosphate cement as a light-cure organic-inorganic hybrid. /. Mater Sci. Mater Med., 23 (7), 1569-1581. 

Normal bone remodeling processes occur around calcium phosphate cement with osteoclastic resorption removing bone followed by deposition of new bone directly on the resorption line (Yuan et al. 2000). Bone growth on pre-hardened cement situated in muscle tissue suggests that bone cement is osteoinductive. 

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