Ceramic Nanoparticles for Whiskers Fabrication to Calcium Phosphate Reinforcement: Synthesis and Characterization

Abstract

The most practical way to repair a bone defect of any size and in any part of the body would be through its replacement with a material which is chemically and morphologically similar to the bone matrix and which stimulates the new tissue growth while it is being degraded. In this context, calcium phosphate cements are excellent candidates, once, besides of being resorbable, they can be moldable into any shape and with a simple viscosity control they became injectable which eliminates the need for major surgical intervention. Furthermore, its setting occurs in vivo and without heat release.The main challenge for the employment of these materials is their extreme fragility which limits their use to small defects in parts of the body which does not undergo large mechanical stress. Thus, there are several research efforts trying to manufacture new systems of bone cement reinforced with polymeric and carbon fibers, however, due to their low compatibility with the cement matrix the results were not satisfactory (dos Santos, et al., 2000; dos Santos, et al., 2003). Furthermore, this cements most of the time are cytotoxic (dos Santos, 2002).The employment of ceramic whiskers on the reinforcement of ceramic matrix is being positively used to produce composite materials for many applications, such as catalyses supports. Nonetheless, the materials commonly applied (carbides and silicon nitrides) do not allow its use in the field of biomaterials because of its high toxicity. Thus, it is extremely interesting to synthesize whiskers of bioceramics which may enhance the material's biocompatibility and overcome the biggest drawback of calcium phosphate compounds: its low mechanical strength.Meanwhile, some researchers have employed hydroxyapatite whiskers to reinforce TTCP / DCPA cement (Müller, et al., 2007). The result obtained were very satisfactory, the flexural strength has been increased by 60% and the work of fracture by 122%. Also, the addition of relatively small whiskers should not change the rheological properties of the calcium phosphate cements which may be positive to its injectability.Thus, the aim of this research proposal it to strengthen some calcium phosphate cement matrix (±-TCP and ²-TCP) with bioceramics whiskers in an attempt to increase the mechanical strength creating a new implantable material with superior biomechanical properties.