Biomedical Engineering Reference
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formation parameters, calcium orthophosphates have been ranked
as follows: low sintering temperature BCP (rough and smooth) ≈
medium sintering temperature BCP ≈ TCP > calcined low sintering
temperature HA > non-calcined low sintering temperature HA >
high sintering temperature BCP (rough and smooth) > high sintering
temperature HA [156]. This sequence has been developed in year
2000 and, thus, neither biphasic TCP, nor triphasic (HA, α-TCP and
β-TCP) formulations have been included. Recent developments
in processing and surface modification of HA have been reviewed
elsewhere [157].
Figure 4.2
Soft X-ray photographs of the operated portion of the rabbit
femur. Four weeks (a), 12 weeks (b), 24 weeks (c) and 72 weeks
(d) after implantation of CDHA; 4 weeks (e), 12 weeks (f), 24
weeks (g) and 72 weeks (h) after implantation of sintered HA.
Reprinted from Ref. [152] with permission.
4.3.3
Forming and Shaping
In order to fabricate bioceramics in progressively complex shapes,
scientists are investigating the use of old and new manufacturing
techniques. These techniques range from an adaptation of the age-
old pottery techniques to the latest manufacturing methods for high-
temperature ceramic parts for airplane engines. For example, reverse
engineering and rapid prototyping technologies have revolutionized
a generation of physical models, allowing an engineer to efficiently
and accurately produce physical models and customized implants
with high levels of geometric intricacy [158-160]. Combined with
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