Biomedical Engineering Reference
In-Depth Information
autografts may cause donor site morbidity.
30
To avoid morbidity,
several types of ceramic-based bone substitutes, which have simi-
lar mineral compositions to natural bone tissue, have been devel-
oped. Among them, synthetic hydroxyapatite (HA) and tricalcium
phosphate (TCP) are the most commonly used ceramics as alterna-
tives to autologous bone.
31
Block-type ceramics have proven use-
ful for reconstruction of segmental bone defects, which are the
major targets in orthopedic applications.
32
In contrast, relatively
small and complicated-shape bone defects (alveolar bone) are the
major targets in oral applications.
33
Since block-type bone substi-
tutes are di
cult to apply for small and complicated-shape bone
defects, ceramic granules have been used. However, reconstruction
of these defects with granules of HA and TCP is more di
cult than
block-type materials and ine
cient partly due to the geometry of
the substratum, which will directly affect the osteoconductive prop-
erties of the materials.
34
Accordingly, granules of natural materials
such as allogenic/xenogenic freeze-dried bones are preferable for
useinalveolarboneregenerationsincethesenaturalmaterialshave
better osteoconductive properties than synthetic HA and TCP.
33
,
35
However, use of allogenic/xenogenic bones cannot completely elim-
inate possible contamination risk (e.g., prions, viruses, zoonosis) or
potential for immunological reactions against allogenic/xenogenic
proteins.
Tissue engineering is an interdisciplinary approach to regen-
erate tissue through integration of cell biology and biomate-
rial/biomedical sciences. Since one of the concepts for tissue
engineering is based on enhancement of the natural healing
process of tissues, it can be considered an ideal therapeutic option
for treating various tissue defects. For bone regeneration, tissue
engineering is considered less invasive than autologous bone trans-
plantation and more e
cient than artificial bone substitutes.
36
Accordingly, bone tissue engineering has been studied extensively
and has even reached the stage of clinical application in some facil-
ities, including our own. Among various target diseases for bone
tissue engineering, application to alveolar bone (oral application)
has attracted much attention because currently available granule-
type bone substitutes for use in alveolar bone regeneration do not
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