Calcium Phosphate Bioceramics: An Alternative to Autograft and Allograft? - Engineered Bone: Tissue Engineering Intelligence Unit - page 66

Figure 4. Hollow cylinders of MBCP ® used in combination with MCS in maxillofacial surgery.
dental applications (Osiris Therapeutics Baltimore) using hollow cylinders of MBCP ®
(Fig. 4).
Conclusion
The bioactive concept based on the dissolution/transformation processes of HA and TCP
can be applied to both Bulk, Coating and Injectable Biomaterials. The mixture of HA and
β -TCP in the 3 different forms have the same evolution and adaptation to the tissues:
1. partial dissolution of the CaP ceramic macrocrystals cause an increase in the calcium and
phosphate concentrations in the local microenvironment;
2. formation of CHA (either by direct precipitation or by transformation from one CaP phase
on an other or by seeded growth) incorporating ions (principally, carbonate) from the bio-
logical fluid during its formation;
3. association of the carbonate-apatite crystals with an organic matrix; and
4. incorporation of these microcrystals with the collagenous matrix in the newly formed bone
(in osseous sites). The events at the CaP biomaterial/bone interface represent a dynamic
process, including physico-chemical processes, crystal/proteins interactions, cells and tissue
colonization, bone remodelling, finally contributing to the unique strength of such interfaces.
Calcium Phosphate Drug Delivery System
Conventional means of administering therapeutic agents generally include oral medication,
eye drops, ointments, intravenous injections and patches. However, the concept of targeted
drug delivery to the site of action, remains of major interest to improve therapeutic efficiency
while producing minimum systemic side effects. 41 Especially a considerable amount of attention is
paid for improvement of drug delivery to sites dramatically limited in access such as bone
tissue. In this context and with regards to their biological and physicochemical properties,
synthetic bone substitutes have been contemplated as potential carriers for the local delivery of
bioactive agents.
Calcium Phosphate Ceramics and Therapeutic Agents Association
The conventional CaP ceramic manufacturing process involves consolidation of powder by
isostatic pressure followed by a sintering step (T>1000˚C) to achieve fusion of particles of the