Biomedical Engineering Reference
In-Depth Information
material, he microstructure of the additional particles for drug incorporation, and additives
to ensure complementary porosity.
The loading of the drug can be performed in several ways. The drug may be included, either
partially or fully, in the powder or in the hydration liquid. Time and temperature for
hydration are selected with regard to the drug and drug loading and to the selected release
criteria. The manufacturing of the carrier can be done completely before or during loading
of the drug. This renders a controlled release time to be selected from a few hours to days
and months.
The drug is introduced in the carrier by mixing the drug into the precursor powder, or the
hydrated CBCs or other porous phases. The material can be formed into a paste by mixing it
with a water-based hydration liquid. The powder can also be pressed into pellets, which
thereafter are soaked in the liquid. The paste or the soaked pellets start to develop the
microstructure that to a great extent will contribute to the controlled release of the drug. The
time and temperature after the mixing will determine the degree of hydration, i.e. the
porosity obtained. The porosity can be controlled within a broad interval of open porosity.
5. Conclusion
The Ca-aluminate technology provides a platform upon which Ca-aluminate based
materials may work as a general biomaterial and as a complement to other chemically
bonded ceramics based on phosphates, silicates or sulphates. Identified areas are in the first
place within the dental and orthopedic areas, where injectable stable biomaterials are
required. These include also properties as bioactivity related to apatite formation,
antibacterial properties as well as nanostructural features useful for carriers for controlled
drug delivery. The studies presented in this paper can be summarised as follows;
Nano-structural integration and apatite formation provide important benefits to both
the dentist and patient, notably minimal micro-leakage, perfect seal at the interface
between tooth and material and as a result longer-lasting treatment results.
The potential use of the Ca-aluminate materials for implant applications is based on the
following features: nanostructural integration with tissue, possible apatite formation,
and a mass increase yielding early point welding between the biomaterial and
surrounding.
The following product areas have been identified based on experimental material data,
pre-clinical studies, pilot studies and on-going clinical studies: dental cement,
endodontic products (orthograde and retrograde), sealants, restoratives, underfillings,
and pastes for augmentation and dental implant coatings.
Consequences of nanostructural contact integration of the Ca-aluminate system are
reduced risk of secondary caries and restoration failure, and reduced post-operative
sensitivity.
The Ca-aluminate material can be used as a vehicle for transport and delivery of the
medicament and as an injectable implant. The combination of the material as carrier
and implant material makes site-specific placement of drugs and implants possible. By
introducing optional additives, or by changing the w/c ratio, the release time can be
controlled from short time periods (a few hours) to prolonged time periods (day and
weeks). The release time is also dependant upon where the drug is placed. In cortical
bone a release time of months seems possible.
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