Biomedical Engineering Reference
In-Depth Information
hierarchical nature of bone with the lowest level of osseous materials in the nanoscale range,
materials with nanometer structures are logically natural choices for fabrication of optimal bone
implants and graft materials for osseous regeneration
[10]
.
When considering bioceramics for bone tissue engineering it is essential to consider the degree
of biodegradability (resorption) as well as the mechanical strength of the materials. For example,
porous hydroxyapatite (HA) and tricalcium phosphate (TCP) have been shown to have excellent
osteoconductive properties, but their biodegradation is poor
[10]
. Nanotechnology has been shown
to play an important role in the development of porous bioceramics with high mechanical strength
and enhanced bioactivity and resorbability
[11,12]
.
19.3
Hydroxyapatite
Nanosized HA is the main component of mineral bone in the form of nanometer-sized needlelike
crystals of approximately 5
20 nm width by 60 nm length
[10]
. Since synthetic HA has been
shown to possess exceptional biocompatibility and bioactivity properties, it has been widely used
clinically in the form of powders, granules, dense and porous blocks, and various composites.
Most recently, for tissue engineering applications the trend is to develop nanosized HA with
properties closer to those of living bone. Nanophase HA properties such as surface grain size,
pore size, and wettability can be modulated for optimal osteoblast adhesion and long-term osteo-
conductivity
[11]
.
nanOss
s
bone void filler originally from Angstrom Medica is considered to be the first nanotech-
nology medical device to receive clearance by the US Food and Drug Administration in 2005.
According to that original developing company and Pioneer Surgical Technology Inc. that now mar-
kets the material, nanOss
s
is an innovative structural biomaterial that is highly osteoconductive and
remodels over time into human bone with applications in the sports medicine, trauma, spine, and
general orthopedics markets. It is formulated by precipitating nanoparticles of calcium phosphate in
aqueous phase and the resulting white powder is compressed and heated to form a dense, transparent,
and nanocrystalline material. It is claimed to be the first material that duplicates the microstructure,
composition, and performance of human bone.
1
Pioneer Surgical Technology Inc. presently has
commercially available nanOss Bioactive Loaded
s
, a prefilled mixing syringe with nanOss mixed
with a collagen-based biopolymer, designed for use in minimally invasive orthopedic surgical proce-
dures as well as nanOss Bioactive 3D bone graft that utilizes the nanocrystalline HA suspended in a
porous gelatin-based foam to promote bone growth in the posterolateral spine.
1
Another commercially available product for use in oral maxillofacial applications, Ostim
s
, also
is comprised of nanocrystalline particles of HA. This material which is available in a syringe as a
ready-to-use paste (Heraeus Kutzer, Hanau, Germany) and contains approximately 65% water and
35% nanoscopic HA particles has been used for augmentation procedures in osseous defects
[13]
.
It should be noted that Ostim
s
does not harden in situ upon mixing with blood or the spongiosa
material at the osseous defect site
[14]
. In a case series to evaluate the healing potential of
intrabony peri-implantitis the application of the nano-HA material resulted in clinically significant
