Biomedical Engineering Reference
In-Depth Information
materials researchers, the biological, medical and clinical aspects
of self-setting calcium orthophosphate formulations have not been
discussed in many details. For additional biomedical details, the
interested readers are referred to other papers and reviews [22, 29,
36, 37, 137, 471, 476, 570].
5.9
Future Developments
As self-setting calcium orthophosphate formulations represent
an intriguing group of new materials for bone augmentation and
reconstruction, there is a great potential for further improvement
of their properties, in which the ideal characteristics (Table
5.4) should be approached by manipulations with the chemical
composition, powder particle size and distribution, as well
as by means of various additives. Several commercial cement
formulations have been already approved for a clinical application
(Tables 5.1 and 5.2). New formulations of both apatite and
brushite cements are expected to appear in the market soon. The
forthcoming commercial formulations will need to be improved in
order to take the advantage of a variety of possibilities offered by
calcium orthophosphate cements. New formulations will include:
(i) injectable and open macroporous formulations to optimize their
osteoconduction [278], (ii) formulations containing only one calcium
orthophosphate (single-phase cement powders) [17] and (iii) drug-
loaded and hormone-loaded cements for the treatment of bone
diseases [29, 36, 37]. Furthermore, incorporation of autologous or
allogenic osteo-progenitor cells in the cement formulations will be
favorable [581-583]. Obviously, the former two directions deal with
both chemistry and material science, while the last two directions
are more related to tissue engineering and medicine.
Concerning the material point of view, an innovative approach of
injectable self-setting formulations has been introduced relatively
recently. The researches combined a water-reactive apatite cement
such as a mixture of TTCP and DCPD powders with a nonaqueous but
water-miscible liquid (e.g.,
glycerol, polyethylene glycol) + a gelling
agent (e.g.,
hydroxypropylmethylcellulose, carboxymethylcellulose,
chitosan) + a hardening accelerator (e.g.,
tartaric, malic, malonic,
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