Production of apatite cements

Inclusion of porosity, with the aim to improve the osteoconductivity, can be introduced by the addition of soluble inclusions such as sucrose, sodium hydrogen carbonate, sodium hydrogen phosphate (Takagi and Chow 2001), or calcium carbonate that reacts to evolve carbon dioxide (Walsh et al. 2001). These reactants produce ionic substitutions in the structure and further improve the resorbability. Another example is that of strontium, which has been shown to be incorporated at low concentrations, while higher concentrations require a heat treatment (Leroux and Lacout 2001b). Since the cement is designed to harden in the body, the composition is modified in situ by reaction with the physiological solutions. 

The low temperature of formation and inherent porosity also permits the addition of antibiotics (Bohner et al. 1997, Takechi et al. 1998) or growth factors that stimulate the differentiation of preosteoblastic cells (Blom et al. 2000). However, the enhanced capability of the cement is somewhat offset by a longer hardening time (Ginebra et al. 2001). 

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