Journal of Biomaterials and Nanobiotechnology, 2011, 2, 318-328
doi:10.4236/jbnb.2011.23039 Published Online July 2011 (http://www.SciRP.org/journal/jbnb)
Bone Remodeling, Biomaterials and Technological
Applications: Revisiting Basic Concepts
Patrícia C. Salgado1, Plínio C. Sathler2,3, Helena C. Castro2,3, Gutemberg G. Alves2,
Aline M. de Oliveira4, Rodrigo C. de Oliveira5, Mônica D. C. Maia6, Carlos R. Rodrigues7,
Paulo G. Coelho8, Andre Fuly2, Lúcio M. Cabral2, Jose M. Granjeiro2
1Program of Post-Graduation in Medical Sciences, Fluminense Federal University, Niterói, Brazil; 2Post-Graduation in Biology of
Interactions, Institute of Biology, Fluminense Federal University, Niterói, Brazil; 3Program of Post-Graduation in Pathology,
Fluminense Federal University, Niterói, Brazil; 4Clinical Research Unit, Antonio Pedro Hospital, Nucleus of Cell Therapy, Fluminense
Federal University, Niterói, Brazil; 5School of Odontology, Fluminense Federal University, Niterói, Brazil; 6Department of
Biological Sciences, Dental School of Bauru, São Paulo University, São Paulo, Brazil; 7School of Pharmacy, Federal University of
Rio de Janeiro, Rio de Janeiro, Brazil; 8Department of Biomaterials and Biomimetics, New York University, New York, USA.
Received March 24th, 2011; revised April 29th 2011; accepted May 8th, 2011.
ABSTRACT
Presently, several different graft materials are employed in regenerative or corrective bone surgery. However current
misconceptions about these biomaterials, their use and risks may compromise their correct application and develop-
ment. To unveil these misconceptions, this work briefly reviewed concepts about bone remodeling, grafts classifica tion
and manufacturing processes, with a special focus on calcium phosphate materials as an example of a current em-
ployed biomaterial. Thus a search on the last decade was performed in Medline, LILACS, Scielo and other scientific
electronic libraries using as keywords biomaterials, bone remodeling, regeneration, biocompatible materials, hy-
droxyapatite and therapeutic risks. Our search showed not only an accelerated biotechnological development that
brought significant advances to biomaterials use on bone remodeling treatments but also several therapeutic risks that
should not be ignored. The biomaterials specificity and limitations to clinical application point to the current need for
developing safer products with better interactions with the biological microenvironments.
Keywords: Biocompatible Materials, Bone Remodeling, Hydroxyapatite, Therapeutic Risks
1. Introduction
In the last ten years, hundreds of thousands of individuals
were affected by deficiencies resulting from trauma, ag-
ing, degenerations and other pathologies involving the
musculoskeletal system. Thus the last decade (2000-2010)
was declared by The World Health Organization as the
Bone and Joint Decade [1].
As a result of the musculoskeletal-related disease high
incidence, the costs and incomes with treatments and
medical support to take caring and maintain the quality
of life of these individuals had significantly increased.
This reinforced the need for novel technologies and me-
thods to provide more feasible and efficient therapeutic
options such as the biomaterials.
In this work, we briefly reviewed several topics related
to Biomaterials that are promising therapeutic alterna-
tives in bone defect treatment. This review approached
different concepts such as bone repair, graft classification
and manufacturing technologies, also including their ap-
plications, advantages and risks. We also provided a
more detailed description of the main characteristics and
issues related to calcium phosphate-based biomaterials.
This alloplastic materials group is of wide application
and is shown as an example of interesting results and
first-hand experience.
1.1. Biomaterials: A Brief Beginning
The term biomaterials, also referred as biomedical mate-
rials, includes any substance (other than drugs) or com-
bination of substances, synthetic or natural in origin,
which can be used for any period of time, as a whole or
as a part of a system, which treats, improves, or replaces
any tissue, organ, or function of the body [2,3]. Areas
such as odontology adopted testing procedures and im-
proved these new biomaterials also allowing fast devel-

Bone Remodeling, Biomaterials and Technological Applications: Revisiting Basic Concepts 319
opment and application processes. In this practice area,
the use of biomaterials go as far as bone grafting in re-
generative or corrective bone surgeries and in procedures
for restoring bone tissue lost during periodontal disease
or endodontic lesions [4,5], filling the alveolar of ex-
tracted teeth to prevent alveolar ridge volume reduction
[6] and lifting maxillary sinus floor and atrophic alveolar
ridge reconstructions [7-9], among others [10].
Currently, biomaterials are subjected to specific stan-
dards for testing and evaluation [11,12]. According to
those, any material intended for clinical use must present
significant biocompatibility defined as “the ability of a
material to perform with an appropriate host response in
a specific application, without eliciting any undesirable
local or systemic effects in the recipient or beneficiary of
that therapy, but generating the most appropriate benefi-
cial cellular or tissue response in that specific situation”
[13,14]. Therefore, the biomechanical properties of a
biomaterial must be adequate and tolerated by the host
tissue [15].
In order to present such desirable features, the bioma-
terials are produced associated to several materials and
substances [16]. For example, the use of bone grafts to-
gether with growth factors such as PDGF, TGF-α and
bone morphogenetic proteins (BMPs) is based on the
association of natural or recombinant proteins to a carrier
such as biological or synthetic polymers (collagen or
poly-L-lactic acid, respectively), ceramics (hydr-oxya-
patite, inorganic bovine bone) and other materials [17].
A great variety of biomaterials is described in litera-
ture for bone bioengineering purposes in cell therapy
[18]. In these cases, the carrier must present (Figure 1):
1) adaptability to the damaged area;
2) osteoconductivity, characterized by good adhesion,
proliferation and maturation of osteoprogenitor cells;
3) ability of acting as a barrier to surrounding tissues;
4) time of resorption compatible to the requirements for
bone formation, without interfering with the substitution
of the material by neoformed bone;
5) biocompatibility, non-immunogenicity and atoxic-
ity;
6) radioluscence, allowing the radiographic distinction
of graft from newly formed bone;
Figure 1. Requirements for biomaterials act as substitute in
bone bioengineering and cell therapy.
7) easy manufacture and sterilization;
8) easy handling during surgery, avoiding complex
preoperatory procedures which increase the risk of infec-
tion and
9) adequate microarchitecture, including interconnec-
tions and porosities (200 - 900 µm), allowing the pene-
tration of osteocompetent and endothelial cells and the
vascularization of the neoformed tissue [18,19].
Several protocols for new biomaterials production and
testing have been described in the last few years, and
some are used regularly in areas such as Odontology and
Orthopedics. However, to understand the principles and
functioning of these biomaterials and their protocols, first
it is necessary to take a look into the targets and bio-
logical systems affected by them.
1.2. Tissue and Bone Repair: Knowing the
Target
Bone represents a specialized conjunctive tissue, charac-
terized by the mineralization of the extracellular matrix
(bone matrix), which can be composed of intramembra-
nous or endochondral ossifications [20]. Intramembra-
nous ossification occurs in the inner portions of the con-
junctive membrane, where mesenchymal cells differenti-
ate in osteoblasts starting bones formation (i.e. mandible
body, frontal, parietal, temporal, maxillary and parts of
the occipital). Differently, in endochondral ossifications
bone is formed over a cartilaginous frame, which is
gradually substituted by bone tissue [21].
At the molecular level, bone is constituted by an or-
ganic portion, representing 35% of the bone matrix com-
posed mostly by type I collagen fibers (95%), together
with proteoglycans, glycoproteins and growth factors
[22]. The remaining inorganic components correspond to
65% of bone weight and include calcium phosphate
crystals with apatite structure. Those crystals are depos-
ited along the collagen fibers and are responsible for the
toughness and resistance of bone tissue [23].
Bone tissue usually presents a remarkable capacity of
repair and regenerated tissue is very similar to the origin-
nal bone. This is in contrast to other tissues that present
the formation of fibrous connective tissue during repair
(i.e. muscle and tendons) [24].
However, there are some conditions in which bone tis-
sue is unable to regenerate correctly. Bone tissue devel-
opment and repair are extremely dependent on extracel-
lular matrix remodeling and local angiogenesis. There-
fore several bone diseases result from the unbalance of
those processes [21,25,26]. In the last decades, some
studies have focused on the role and regulation of bone
remodeling through apposition and resorption [27]. One
of their main purposes was to identify signaling proteins
and their role in such processes [21,25,28].

Bone Remodeling, Biomaterials and Technological Applications: Revisiting Basic Concepts 320
Literature described the bone remodeling dependence
on growth factors, cytokines, BMPs, matrix metallopro-
teinases (MMPs), alkaline phosphatase, tartrate-resistant
acid phosphatase (TRAP) and nitric oxide (NO) [29],
which regulate apposition and resorption in a structured
way. Bone repair also depends on an adequate blood
supply, mechanical stability cell migration, matrix depo-
sition and remodeling, among other processes [21,30-32]
(Figure 2).
The use of biomaterials as promoters of bone repair
may lead to: 1) formation of a surrounding fibrous con-
nective tissue, known as repair by cicatrization that is an
undesired process, or 2) material absorption and close
integration to the tissue, known as repair by regeneration
that is desirable to clinical use [33-35].
The regenerative bone repair processes become more
predictable with the Guided Tissue Regeneration (GTR)
technique. It is characterized by a physical barrier that is
placed around to the damaged area or to the biomaterial,
to promote bone cells proliferation and exclude undesir-
able cells. The bone cells proliferation is responsible for
the regeneration of the damaged or lost tissue [36-39]
(Figure 2).
1.3. Biomaterials and Blood: Feeding the System
The survival of osteocytes in grafted bone is directly re-
lated not only to blood vessels support but also to viable
surfaces of both endosteum and periosteum. Usually,
grafts originated from bone marrow present a higher
probability of helping cell survival by improving nutrient
diffusion and promoting revascularization [17].
Besides nutrient and oxygen supply, the coagulation is
another important aspect of the close relation between
biomaterials and blood. Although many osteoconductive
and degradable biomaterials are available, some interfere
with platelet function or the coagulation cascade. There-
fore the risk of thrombus formation during, and after
prosthetic surgery increases for the patient [40].
Sometimes postoperative deep vein thrombosis occurs
due to the biomaterial release into circulation (i.e. Bone
Cement Implantation Syndrome - BCIS) [41-43]. In other
cases, soluble components on bone cements are consid-
ered toxic (i.e. methacrylate monomers) [40,44].
The contact between blood and a specific biomaterial
may lead to several other coagulopathies and vascular
disorders, as well as pulmonary, renal and neuronal dys-
functions [45]. Usually, these disorders are associated
with mild to strong inflammatory reactions. Indeed, the
activation of blood plasma cascade systems (coagulation,
complement and kallikrein systems) occurs right after
blood contact with the biomaterial with subsequent ad-
sorption of plasma proteins, depending on the biomate-
rial structural and chemical features [46,47].
Figure 2. Stages of process bone tissue repair. Inflamma-
tory, proliferative and remodeling phases.
Usually the inflammatory response to biomaterials starts
with the activation of the complement system and C3b
deposition on the biomaterial surface. The sub-sequent gen-
eration of C3a and C5a triggers leukocyte release of cyto-
kines, prostaglandins and leukotrienes, with a wide range
of pharmacological effects on cells [48,49] (Figure 3).
The activation of complement also induces platelet
aggregation as well as the coagulation system. Even tough
these mechanisms are not fully understood, the participa-
tion of the intrinsic and extrinsic pathways as a whole
has been reported [48,50,51].
Therefore, safety evaluation is almost as important as
the development of new biomaterials for any area of use.
This should be prior and during the biomaterial appli-
cation and obviously includes studies involving the bio-
materials interaction with all blood systems.
1.4. How and Why Classify Biomaterials?
Biomaterials may be classified based on different bio-
logical features including postgrafting action and origin.
These features are important to the procedures and the
required attention as well as the further studies for fully
understand of the biomaterial effects (Table 1).
1.5. Postgrafting Action
Bone grafts can be classified as osteogeneic, osteoinduc-

Bone Remodeling, Biomaterials and Technological Applications: Revisiting Basic Concepts 321
Figure 3. Complement syste m activation through binding to
the biomaterial surface. The activated complement attracts
immune cells and triggers inflammation.
Table 1. Comparison of biological characteristics of bioma-
terials based on their origin and biological profile.
Classification
Based on Type Biological Characte r i s tic
Osteogeneic
Living bone cells are inserted onto a
receptor site and maintains the capacity
of generating novel bone tissue
Osteoinductive
Mesenchymal stem cells of graft site
surroundings are induced to differentiate
into osteogeneic cell lineages
Osteoconductive
able to orient the formation of new bone
tissue through its support matrix, acting
as a scaffold that can be simultaneously
absorbed and substituted by bone tissue
Biological
profile
Osteopromotive Allows Guided Tissue Regeneration
(GTR)
Autogeneic obtained from unaffected donor sites
from the own receptor individual
Allogeneic
obtained from the bone tissue of an
individual of the same species of the
receptor
Xenogeneic obtained from individuals of different
species from the donor
Origin
Alloplastic
synthetic materials, manufactured in
different shapes, textures, sizes and
compositions
tive, osteoconductive and/or osteopromotive based on their
biological effects after implantation onto a bone defect.
Some materials may be classified into more than one
functional class, thus requiring attention and further stud-
ies for fully understand of the biomaterial effects.
Osteogeneic: in osteogeneic grafts, living bone cells
are inserted onto a receptor site and maintains the capac-
ity of generating novel bone tissue. Autogeneic bone
represents the main example of a graft material with os-
teogeneic properties, since it is able to form bone tissue
even in the absence of undifferentiated mesenchymal
cells. In fact, autogeneic graft materials are also able to
induce osteoinduction, osteoconduction and osteopromo-
tion [24], as described in the following sections.
Osteoinductive: This is a common classification for
some graft materials in which mesenchymal stem cells of
graft site surroundings are stimulated to differentiate into
osteogeneic cell lineages. This mechanism is directly
related to the activity of BMPs [52,53]. Osteoinductive
grafts contribute significantly to the formation of new
tissue during bone remodeling processes. This is mainly
observed by using platelet-rich plasma, growth factors,
demineralized lyophilized bone or frozen/irradiated
autogeneic bone [54].
Osteoconductive: This biomaterial is able to orient the
formation of new bone tissue through its support matrix,
acting as a scaffold that can be simultaneously absorbed
and substituted by bone tissue [55]. Osteoconductive
biomaterials allow for bone apposition on their surfaces,
guiding the repair from the border of the lesion to its
center. Osteoconductive media do not promote osteoblast
differentiation but ease inner bone growth and fibrovas-
cular tissue formation on the graft area [56,57]. Cortical
autogeneic bone, allogeneic mineralized tissue from bone
banks and alloplastic or synthetic materials such as ce-
ramics, polymers and composites are examples of osteo-
conductive materials.
Osteopromotive: The principle of osteopromotion is
related to the Guided Tissue Regeneration (GTR) and the
properties of physical membranes or barriers. Currently,
two classes of barriers can be used for such purpose: a)
absorbable (ex: polylactic acid, polyglycolic acid or type
I and type III collagen) and b) non-absorbable mem-
branes (ex: expanded-polytetrafluorethylene – e-PTFE).
The barrier selection is directly linked to defect type,
cost/benefit ratio and availability and/or interest of the
patient in submitting to a second surgery for the removal
of non-absorbable membranes [37,58,59].
Those barriers, when employed on GTR, should obey
the following criteria:
1) biocompatibility;
2) permeability, allowing the diffusion of plasma and
nutrients, but impending the transit of cells;
3) provide physical support to surrounding soft tissues,
preventing them to collapse into the blood clot space;
4) protect blood vessels while the clot undergoes a re-
organizing process;
5) exclude competitive cells;
6) prevent the formation of scars
7) present easy handling [37].

Bone Remodeling, Biomaterials and Technological Applications: Revisiting Basic Concepts 322
1.6. Origin
Another classification for biomaterials is based on their
origin, which include autogeneic, allogeneic, xenogeneic
or alloplastic. These classes are briefly described below
with the advantages and disadvantages, including a more
detailed description of allogeneic calcium phosphate ma-
terials [60].
Autogenous bone grafts: Also known as autografts,
they are obtained from unaffected donor sites from the
own receptor individual. The regeneration of the bone
defect occurs by mechanisms involving osteogenesis,
osteoinduction and osteoconduction [17,46,61,62]. These
are the most used grafts due to their biocompatibility and
non-immunogenicity, being considered sometimes as
standards for bone-grafting [61]. In this graft type, the
autogeneic bone matrix allows for the transference of
living bone cells from the donor site to the receptor re-
gion.
Autogeneic grafts can be extracted from cortical bones,
their medullary portions or a combination of both [17].
According to literature, bone-marrow grafts are most
efficient due to their higher content of osteoprogenitor
cells [63]. They can be obtained by both extraoral (iliac
crest, tibia or skull) or intraoral areas (retromolar region,
mandibular symphisys and maxillary tuberosities), de-
pending on the volume and composition of the desired
graft [10]. Once collected, the autogeneic material should
be used immediately or stored in lactated Ringer medium
or saline physiological solution to maintain cell viability.
In the other hand, autogeneic grafts present some dis-
advantages/risks, which for extraoral grafts, include: 1)
patient hospitalization, 2) morbidity of the donor site, 3)
post operatory scars and 4) discomfort during recovery.
Differently, for intraoral grafts they are 1) higher pa-
tient’s morbidity and 2) limited quantity and quality of
material available for collecting [16,23,61]. These risks
have stimulated the development of bone grafts from
alternative biomaterials.
Allogenous bone grafts: They are obtained from the
bone tissue of an individual of the same species of the
receptor. The allogeneic grafts present osteoinduction
and osteoconduction abilities, being processed in sterile
conditions and stored in bone banks [16,23,64]. The ad-
vantages of allogeneic bone grafts are 1) no need of a
donor site, 2) reduced use of anesthetics, 3) less bleed-
ings, 4) unlimited amounts of graft material and 5) lower
risks of surgical complications. Their main disadvantages
include mostly 1) risk of transmission of infectious dis-
eases, 2) host immune response and 3) lower predictabil-
ity for the grafting outcome.
Allogeneic grafts can be commercialized in several
different forms, reflecting on different production costs
and efficacies including:
1) frozen grafts, known as the most antigenic form;
2) lyophilized grafts, produced by washing the cortical
and medullary bone from the donor, followed by tritu-
rating, nitrogen freeze-drying, sterilization by ethylene
oxide or irradiation and storage;
3) lyophilized and demineralized grafts, through a pre-
vious treatment with 0.6 M nitric or chloridric acid and
4) irradiated grafts, which present some controversies
by the lack of references on safety and efficacy of their
osteoinductive properties [65].
Xenogenous bone grafts: They are also known as
xenografts and are obtained from individuals of different
species from the donor [66]. The most common grafts are
collected from bovine bone, but literature also described
porcine or caprine materials [23]. Their use presents
similar advantages of allogeneic grafts, with predictable
results when surgical rules are followed [67]. On the
other hand, there are also disadvantages including: 1) the
risk of interspecific transmission of infectious diseases, 1)
host immune response and 3) lower acceptance by pa-
tients and professionals due to cultural and religious as-
pects of using animals material.
Alloplastic bone grafts: These are synthetic materials
manufactured in different shapes, textures, sizes and
compositions. This category includes metallic grafts and
their alloys, calcium phosphate ceramics (hydroxyapatite
and tricalcium phosphate), calcium carbonate, calcium
sulphate, Hard Tissue Replacement (HTR) polymers and
bioglass [68]. These materials can be classified based on
their porosity (dense, microporous or macroporous),
crystallinity (crystalline or amorphous) and solubility
(absorbable or unabsorbable) [69,70].
Synthetic grafts are associated to an osteoconductive
action, characterized by bone growth into the graft mate-
rial matrix, which acts as a scaffold to the regeneration of
lost bone tissue [16,61,63,69].
Besides their biological properties, these materials also
present relevant chemical (main composition, impurities
and ionic reposition) and physical characteristics (shape,
porosity, surface area and crystallinity), which directly
affect material absorption function, velocity and range
[65,71].
Other characteristics such as morphology, roughness,
wettability and surface energy of the employed biomate-
rial also affects cell adhesion, proliferation and differen-
tiation, specially on osteoblasts, contributing to the for-
mation of either fibrous or bone tissue [65,72]. Therefore,
the manufacture of alloplastic materials for bone regen-
eration purposes must be submitted to accurate controls
that verify the physical, chemical and mechanical proper-
ties of the material [73].

Bone Remodeling, Biomaterials and Technological Applications: Revisiting Basic Concepts 323
1.7. Biomaterials Based on Calcium Phosphate
Calcium phosphates have been used for a long time as
alloplastic materials for bone grafts or as a cover for
dental implants. They are known as bioactive materials,
due to their capacity of actively participating on both
cicatrization and regeneration of bone tissue [74]. This
capacity results from the similarity between calcium
phosphate materials and the apatites found on bone tissue
[23,63,69].
The major advantage of calcium phosphate-based graft
materials is that both calcium and phosphate ions do not
interfere on cell function and physiology of adjacent tis-
sues. This feature grants a favorable tissue response to
treatment with adequate toughness and mechanical resis-
tance to compression. Furthermore, due to partial disso-
lution onto the physiological medium, these materials
release phosphate and free calcium ions. These ions seem
to act as catalysts for bone formation and precipitation of
a carbonated apatite layer over the surface of the bioma-
terial, which allow the chemical bonding to the neo-
formed bone [57,63].
Calcium phosphates can be manufactured on micro-
porous (dense) or macroporous forms. Microporous ce-
ramics present maximum porosity of 5% per volume,
with a maximum pore diameter of 1 μm. This results in
highly dense materials, with elevated resistance to com-
pression [70]. Macroporous calcium phosphates, on the
other hand, present 100 μm to 500 μm diameter pores,
which comprise 15% or more of the total volume of the
material. Its inner architecture, including size, shape and
communication among pores, have an important role on
the in vivo behavior of the biomaterial [75-77]. Therefore,
for biomaterials with the same chemical composition, the
highest is the porosity, the fastest is the absorption speed
for the graft material [70].
A combination of analytical techniques is recom-
mended to address the crystalline properties of calcium
phosphate-based biomaterials. Such techniques include
X-ray diffraction (XRD), Fourier transform infrared
spectroscopy (FT-IR), scan (SEM) and transmission
electron microscopy (TEM) and solubility assays [78-81].
Each one of those approaches provide specific data, and
present particular limitations, causing the need for their
combined use to characterize correctly the material [80].
1.8. Future Perspective
Biomaterials are artificial or natural materials that may
help on restoring form and function of organs and func-
tional sites and structures. Thus they not only directly
help in improving human quality of life but also attend
the aging population needs [3].
The future of biosynthetic bone implants still point to
autologous bone grafts. There is an increasing interest in
combining osteoconductive proteins in osteoconductive
carrier media to facilitate timed-release delivery and/or to
provide a material scaffold for bone formation. Further,
advances in tissue engineering, which integrate the bio-
logical, physical and engineering sciences allow the gen-
eration of new carriers to repair, regenerate and restore
tissue to its functional state. These new products modu-
late different growth factors, evolving biological scaf-
folds and incorporation of mesenchymal stem cells. Ul-
timately, the development of ex vivo bioreactors with
biomechanical features may provide tissue-engineered
constructs for using directly in the skeletal system.
The future of bone graft substitutes continues to be an
expanding topic of interest [82]. The current biomaterials
are not able to replicate the surface totally and/or the
properties of the replaced bone, leading to failure due to
insufficient bonding with juxtaposed bone, bone loss,
implant loosening and/on fracture.
Nanophase materials possess unique surface and me-
chanical properties similar to the bone and, hence are
considered to be the future generation of orthopedic
biomaterials [3]. In fact, lately, the engineering devel-
opment (i.e. nanotechnology) is greatly increasing bio-
materials complexity as well as their biological functions
[83]. Biomaterials academic research data such as the
analysis of interaction with the host (i.e. binding interac-
tions with cell surface receptors) and applied methodo-
logical data such as self-assembly have been used for
designing new biomaterials capable of modulating the
maintenance and regeneration of specific tissues in the
body [84,85].
Currently, to produce new more effective and safer
biomaterials, the researchers should consider that bioma-
terials may modulate specific cell populations distant
from the implant site. This can be done either by target-
ing the material to specific cells or anatomical locations
or by controlling the trafficking of target cell populations.
Recent reports showed biomaterials as regulators of the
immune system and polymeric nano particles designed
for non-invasive delivery into the body [86] and for traf-
ficking through the lymphatic vessels to target T cells in
the lymph nodes [87]. Similarly, nanoparticles are being
designed to exploit the chemical and physical differences
between normal and tumor-associated vasculature to
concentrate the particles selectively within or near tu-
mors, allowing subsequent drug-induced cell death [88].
Materials can also be designed to regulate outward mi-
gration of transplanted stem cells, or their differentiated
progeny to fulfill damaged tissues and promote regenera-
tion efficiently [89].
Clearly the advances in biomaterials will include the
development of more functional medical materials and

Bone Remodeling, Biomaterials and Technological Applications: Revisiting Basic Concepts 324
the expanded use of biomaterials into new applications.
Thus, to mimic important biological processes and/or
their functional behavior, it is necessary to fully under-
stand these processes complexity and dynamic, which
knowledge is not currently available in most cases. The
application of the molecular templating of viruses to op-
toelectronic device fabrication is an example of this ap-
proach [83,90]. Biological systems have already in-
spired the development of cell-programming matrices
based on knowledge about infection process, and these
matrices accomplish their task with a small subset of key
molecular stimuli [91].
The biomaterials research including those with aca-
demic and/or industry application purposes is quickly
growing and should be redefined. This new definition
may include materials that are able to modulate biologi-
cal processes and those whose design and functions are
inspired by natural materials since they may be crucial
for improving human quality of life.
2. Conclusions
This brief review showed that the biotechnological de-
velopment initiated in the 50’s was accelerated in the last
ten years with significant advances for using biomaterials
on treating bone remodeling related processes (i.e. or-
thopedic and odontological treatments). Particularly, cal-
cium phosphates have performed as important biocom-
patible materials to bone tissue reposition. However to-
gether with these innovations, critical risks were identi-
fied that can be controlled or avoided by the knowledge
about the product features and their interactions with the
biological microenvironments.
Based on these data, all future research may focus on
addressing both chemical and physical characteristics of
biomaterials to better interact with these microenviron-
ments. On that purpose the biological and toxicological
profile of each biomaterial must be determined previ-
ously to its clinical application to establish its limitation
and specificity. Special attention must be given to the
principles that rule a new interface, to obtain safer and
effective therapeutic treatments.
3. Acknowledgments
We thank the Conselho Nacional de Desenvolvimento
Científico e Tecnológico (CNPq), Coordenação de
Aperfeiçoamento de Pessoal Docente (CAPES-Edital
Nanobiotecnologia 2008) and Fundação de Amparo à
Pesquisa do Estado do Rio de Janeiro (FAPERJ) for the
financial support and fellowships.
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