Biomedical Engineering Reference
In-Depth Information
The injectability of chemically bonded ceramics is mainly
controlled by the added water as the reacting phase with the
powdered cements. This reaction is an acid-base reaction where
water acts as a weak acid and the cement powder as a base. The
technological importance of this is that all the water needed for
injectability can be consumed in the formation of solid phases,
yielding products with low porosity, one of the requirements for
high strength—details in Chapter 3.
10.2.2
Ca-Aluminate-Based Orthopaedic Coating
Materials
For successful implantation of implants in bone tissue, early
stabilisation is of great importance [17]. Even small gaps may
lead to relative micromotions between the implant and the tissue,
which increases the risk of implant loosening over time due to the
formation of zones of fibrous tissues at the implant-tissue interface.
Early loading of implants is of particular interest for dental implants
[18]. The use of surface-coating technology is today an established
method to reduce the problem of poor interfacial stability for
implants. With coating technology, structural characteristics of the
implant (e.g., strength, ductility, low weight, or machinability) may
be combined with surface properties promoting tissue integration
[19]. There are several established coating deposition techniques,
for example, physical vapour deposition (PVD) (sputtering) and
thermal spraying techniques [20, 21]. Among CBBCs, Ca-phosphates
are the most used coating materials.
This section deals with coatings deposited with established
methods, with the aim of improving particularly the early-stage
anchoring of metal implants to bone tissue by exploring in vivo
hydration of coatings or pastes based on chemically curing ceramics.
The study focuses on Ca-aluminate in the form of coatings and
paste. Results are presented from an implantation study with
flame-sprayed coating on titanium implants and uncoated implants
augmented with a Ca-aluminate paste in the hind legs of rabbits.
Implants were applied with the paste composed of a mixture of
CaO·Al
. The paste was applied manually as a thin
layer on the threaded part of the implant just before implantation.
The uncoated and coated implants were sterilised with hot dry air
O
and CaO·2Al
O
2
3
2
3
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