13 Tissue engineering applications and nanobiomaterials in periodontology and implant dentistry










CHAPTER
13
Tissue engineering
applications and
nanobiomaterials in
periodontology and implant
dentistry
Huseyin Gencay Keceli
1
, Abdullah Cevdet Akman
1
, Cem Bayram
2
and
Rahime Meral Nohutcu
1
1
Periodontology Department, Faculty of Dentistry, Hacettepe University, Ankara, Turkey
2
Hacettepe University, Advanced Technologies Application and Research Center Beytepe,
Ankara, Turkey
13.1 NANOBIOMATERIALS AND IMPLANT DENTISTRY
Depending on tooth loss due to developmental anomalies, caries, periodontal
disease, or trauma, dentition needs therapeutic modalities to regain its aesthetic
and functional properties. Conventional therapy involving fixed or removable
dentures may have indispensable inadequacies such as insufficient occlusal
activity, ongoing alveolar bone loss, limited material biocompatibility and
strength. Secondary problems including tooth fracture and dental caries may also
occur (
Davarpanah et al., 2000).
From the 1980s, dental implants have been presented as a revolution for
supporting the functional restorations and have been put into routine clinical dental
practice. Implant installation has been rega rded as a treatment of choice for edentu-
lous patients because of its biocompatibility and stability (
Douglass and Watson,
2002; Douglass et al., 2002). Until today, various implant types like “transosteal,”
“subperiosteal,” and “endosteal” have emerged (Iacono, 2000
)(Figure 13.1).
Today, the most reliable one in clinical utilization is the endosteal type because of
its superiority in surgica l morbidity, force distribution, and aesthetics. Clinically,
implant selection needs experience and thorough evaluation, considering the
parameters of bone dimensions and quality (
Iacono, 2000)(Figure 13.2).
Commonly encountered situations related to implant failure could be summarized
as insufficient cell proliferation at the implant surface, cell death at the vicinity of
implant due to erosion, and debris caused by the rough surface, and loosening and
337
Nanobiomaterials in Dentistry. DOI: http://dx.doi.org/10.1016/B978-0-323-42867-5.00013-8
© 2016 Elsevier Inc. All rights reserved.

fractures which originate from the load and stress imbalance between the implant
and surrounding tissue. From this point of view, induction of bone formation
around the implant and a rapid integration to juxtaposed bone is required to
overcome these problems, so the surface of the implant must be appropriate for
osteoblast colonization and bone tissue synthesis.
In this part, to understand the relationship between nanotechn ology and dental
implants, critical features of the tissues surrounding the dental implants and
underlying mechanisms related to the osseointegration concept will be reviewed
first. Then, from macro- to nanolevel, the properties of the dental implant surfaces
and their interactions with these tissues will be evaluated. This text also aims to
inform the readers of recent techniques aimed at enhancing bone formation and
improving osseointegration.
FIGURE 13.1
Types of dental implants.
FIGURE 13.2
In addition to experience and thorough evaluation, successful implant treatment can be
achieved by considering the parameters of bone dimensions, quality, and functional needs.
338 CHAPTER 13 Tissue engineering applications and nanobiomaterials

13.1.1 DENTAL IMPLANTS: PERSPECTIVE
FROM SURROUNDING TISSUES
Soft tissue around dental implants is a specialized mucosa and named the
peri-implant mucosa that represents similar properties to periodontal tissues.
Peri-implant mucosa consists of epithelium and connective tissue layers and its
main function is to protect the underlying tissues from mechanical and bacterial
attacks (
Listgarten and Lai, 1975; Swope and James, 1981). According to its
localization over the implant surface, epithelium has three portions, oral, sulcular,
and junctional (Figure 13.3
). The height of sulcular epithelium represents the
depth of the peri-implant sulcus, and depends on the thickness of keratinized
tissue overlying the alveolar bone. For optimal health conditions, values from one
to three are suggested. The distance between the top and bottom of junctional
epithelium is 11.5 mm (
Berglundh et al., 1991). The tip of peri-implant mucosa
is less vascularized and, therefore, requires gent le handling during surgery
(
Figure 13.4).
Collagen (mainly type I) is a fundamental component of the connective tissue
(
Chavrier and Couble, 1999). Differing from gingival mucosa around natural teeth,
peri-implant mucosa has a lower number of fibroblast cells and rather than perpen-
dicular, collagen fibers lie parallel to the implant surface (
Berglundh et al., 1991).
The interface of connective tissue and implant is called the connective tissue
attachment and its ideal height is 1.52mm (
Berglundh et al., 1994). When soft
FIGURE 13.3
The main parts of an endosteal implant and its surrounding soft (peri-implant mucosa)
and hard (alveolar bone) tissues.
33913.1 Nanobiomaterials and Implant Dentistry

tissue height is below this level, bone resorption may occur after implant
placement to establish the desired amount of mucosa thickness (
Berglundh and
Lindhe, 1996
). If the soft tissue is too thick, a deep peri-implant sulcus may occur
after implant placement that impairs plaque removal (
Figure 13.5).
Alveolar bone surrounding the implant is comprised of organic and inorganic
matrices. The composition of organic matrix is collagenous and noncollagenous
FIGURE 13.4
The tip of peri-implant mucosa is less vascularized and, therefore, requires gentle
handling during surgery. Note the whitish color of peri-implant mucosa easily affected by
inappropriate cap placement.
FIGURE 13.5
Peri-implant tissue thickness is an important factor for maintaining the health of
surrounding tissues. A deep peri-implant sulcus may impair plaque removal and cause
peri-implant disease.
340 CHAPTER 13 Tissue engineering applications and nanobiomaterials

proteins, whereas inorganic matrix is comprised of ions (mainly Ca and P) and
hydroxyapatite (HA) structure s. Alveolar bone encounters chewing loads, protects
the nervous system, and contributes to mineral homeostasis. The primary cell
type in the bone is the osteoblast which participates in bone formation, organic
matrix synthesis, and inorganic matrix mineralization. Bone-lining cells are the
second group that covers bone tissue with no synthetic function. Osteocytes are
the third group, trapped inside the synthesized bone matrix, providing communi-
cation to the other bone cells with their processes and increasing the contact area
between cells and organic matrix. They also play a role in systemic Ca hemostasis
and make signal transduction during mechanical forces. The fourth group, osteo-
clasts, are bone cells responsible for resorptive activity that is maintained with
formative process in a balance and activated in case of a pathologic event such as
periodontal disease, trauma, etc. These cells are multinuc leated and originate
from progenitor cells of the hematopoietic system. Osteoprogenitor cells are the
fifth group and migrate to the injured site and differentiate into osteoblasts during
bone formation. Two types of osteoprogenitor cells are present, inducible and
determined. Determined cells can reside in endosteum, periosteum, or bone mar-
row and are capable of proliferating and differentiating into osteoblasts. Inducible
cells are commonly known as mesenchymal stem cells (MSCs). Although lower,
the submucosa of implant-related tissues (gi ngiva, periosteum, alveolar bone) also
incorporates MSCs. They have two specific properties; being capable of renewing
themselves even after extended inactive periods and being stimulated to synthe-
size specific tissues/organs by inducing their differentiation and other special
functions. Even though the main origin of MSCs is bone marrow (
Friedenstein
et al., 1968
), they are also present and can be isolated from various other tissues
(
Friedenstein et al., 1968; Zannettino et al., 2008; Wickham et al., 2003;
Hoogduijn et al., 2007; Jo et al., 2007; He et al., 2007; Oh et al., 2008;
Morganstein et al., 2010; Marinucci et al., 2010; Lepski et al., 2010; Engler et al.,
2006; Chivu et al., 2009; Liu et al., 2007).
Before implant placement, the amount of residual alve olar bone may
complicate the therapy and, thus, utilization of bone substitutes or guided
bone-regeneration techniques might be needed. Following application of these
approaches and/or placement of dental implants, three main bone-related events
may occur: osteogenesis, osteoinduction, and os teoconduction. Osteogenesis is
the natural formation activity of the bone that occurs in the presence of a high
number of vital osteoblasts/osteop rogenitor cells inside the bone cavity or at the
boneimplant interface. Autogenous bone grafts and bone marrow grafts are
well-known examples of treatments providing osteogenesis. Osteoinduction
is the process that bioactive proteins enhance proliferation and differentiation of
cells responsible from bone synthesis. These bioactive proteins related to
osteoind uction, commonly known as growth/differentiation factors, mainly reside
in bone matrix and their synthesis can be externally induced for enhancing
osteoind uction and implant osseointegration (
Giannob ile and Somerman, 2003;
Reynolds et al., 2003).
34113.1 Nanobiomaterials and Implant Dentistry

13.1.2 DENTAL IMPLANTS: PERSPECTIVE
FROM OSSEOINTEGRATION
There are two concepts carrying priority in survival and success of implant treat-
ment, primary stability and osseointegration. Primary stability is defined as
immediate mechanical anchorage of the implant to surrounding alveolar bone.
Bone quantity, quality, and implant surface characteristics have been indicated as
the main factors influencing primary stability (
Roos et al., 1997). The other, but
overriding, phenomenon is osseointegration which is defined as the functional
binding between surfaces of dental implant and circumjacent living alveolar bone
without any soft tissue interference and is a unique and multistep process
(
Branemark et al., 1995). These steps are reviewed below.
After drilling, vessels of trabecular bone are injured and the relationship
between implant and its adjacent tissues begins with titanium surfacevascular
unit contact (
Figure 13.7). With this contact, plasma proteins inside the blood
are absorbed by the surface in a few minutes, thrombocytes are activated and
clotting occurs with thrombus and fibrin formation. During clotting, plasma
proteins modify the titanium surface and several cell types move and attach to
this modified interface by their integrin receptors. Cell attachment is promoted
by cell-binding RGD domains (Arg-Gly-Asp) of adsorption proteins such as
vitronectin and fibronectin. Fibronectin/vitronectin is locate d on membranes of
many cell types and the RGD domain interacts with extensions of these proteins
(
Balasundaram et al., 2006).
Attraction of MSCs to the biological activity area is one of the most critical
factors to achieve bone synthesis by their proliferative activity and differentiation
(
Agis et al., 2009; Vogel et al., 2006). These activities are induced by growth/
differentiation factors involving vascular endothelial growth factor (Fiedler et al.,
2005
), epidermal growth factor (EGF) (Ozaki et al., 2007; Kuznetsov et al., 1997),
platelet-derived growth factor (PDGF) (Mishima and Lotz, 2008; Ozaki et al., 2007),
transforming growth factor (TGF-β)(Mishima and Lotz, 2008; Jian et al., 2006), and
bone morphogenetic proteins (BMPs) (Mishima and Lotz, 2008; Fiedler et al., 2005).
Moreover, fibrin is a 3D healing tissue matrix composed of bioactive molecules/
factors that are slowly released to the injury site and enhance chemotaxis and
growth of MSCs (Catelas et al., 2006, 2008; Wong et al., 2003; Mosesson, 2005;
Rock et al., 2006). Under the effect of growth/differentiation factors within a
fibrin matrix, MSCs are also capable of differentiating into osteoblastic cells and
with this process, bone formation is provided on the boneimplant interface.
All steps of cellular activity are influenced and manipulated by surface features of
dental implants.
After a few weeks, primary stability leaves its place to living boneimplant
contact (BIC) by achievement of bone formation with secondary mechanisms tak-
ing the process into osseointegration (
Branemark et al., 1969, 1983; Linder et al.,
1983). When achieved and able to be maintained long term, it is known as the
key factor of predictability in front of constant chewing loads (Adell et al., 1990
).
342 CHAPTER 13 Tissue engineering applications and nanobiomaterials

Besides new bone formation, hematoma and necrotic bone particles are moved
away from the environment by macrophages and osteoclasts residing inside the
granulation tissue. To maintain their formative activity, osteoblasts are attached to
the surface. After covering the whole implant surface with de novo bone and
completion of the formation process, osteoblasts transform into osteocytes that
have their own surrounding matrix and products. The first type of bone formed
over the implant is woven bone that transforms into more organized and dense
lamellar bone by remodeling over a few months (
Adell et al., 1990; Jan Lindhe
and Lang, 2008). At this step, the connection between alveolar bone and implant
is at its “weakest” (Jan Lindhe and Lang, 2008
).
If any location of implant is surrounded by fibrous tissue owing to fibroblast
proliferation, the process is called fibro-osseo us integration, which is considered
a negative outcome (
Davies, 2003). During this process, MSCs differentiate into
fibroblastic cells instead of osteoblasts, and fibroblasts produce a collagen capsule
preventing direct BIC during integration. Fibrous soft tissue may cause an
improper fixation that later leads to a probable implant failure and also inhibits
new bone formation indirectly by affecting the osteoblast/osteoclast balance
(
Hobkirk, 1983).
13.1.3 DENTAL IMPLANTS: PERSPECTIVE FROM MATERIALS
Pure titanium (pTi) or titanium alloys (Ti
6
Al
4
V) are the most widely used and
highly biocompatible materials. Alloys have higher fatigue and yield strength
and they are comprised of fifth-grade titanium (
Hobkirk, 1983). When the surface
of the titanium is exposed to air, a titanium oxide layer providing direct bone
implant connection occurs (
Oshida, 2006).
Ceramic materials have also been used as implant materials. Thirty years ago,
aluminum oxides in polycrystalline (PC; generic name: Frialit-1) and single
crystal (AO; generic name: Kyocera) forms were used in clinical practice.
Nowadays, the interest in implant surface material technology assembles on
another ceramic, zirconia (ZrO
2
). In dentistry, zirconia is not a new material and
has been already used in crown and bridge fabrication and successful outcomes
were reported after testing in vivo and in clinical models (
Akagawa et al., 1998;
Kohal et al., 2004; Oliva et al., 2007).
13.1.4 DENTAL IMPLANTS: PERSPECTIVE
FROM SURFACE PROPERTIES
Implant surfaces providing the nearest contact with adjacent bone are desired to
enhance osseointegration (
Stanford and Brand, 1999)(Figure 13.6). Macro- and
microlevel features residing over surface structure of dental implants are described
as surface topography and these features determine the micromechanical relation-
ship of implant with surr ounding bone. Surface roughening is the best-known
34313.1 Nanobiomaterials and Implant Dentistry

method to increase surface area of BIC, which may lead to obtaining greater area
to encountering the forces directed at the boneimplant interface (
Wennerberg
et al., 1997; Hansson, 1999, 2000; Buser et al., 1991). Though surface roughness
provides better clinical and histologic results, it is still not certain to think of the
roughness as the single key of success (Wennerberg and Albrektsson, 2000
).
On the other hand, roughness is also a confounding and complicating factor in
making comparisons between different dental implant systems.
Features of implant surface topography can be classified according to the
modifications in macro-, micro- or nanosized level. Macrolevel is topologic detail
(1 mm to 10 μm) that can be set by creating threaded screws, solid body press-fit
designs, and sinter ing technologies. Since alveolar bone responds favorably to
compressive stresses instead of shear forces (
Stanford, 1999), most of the thread
designs have been created to reduce shear forces at the thread tip and transmit
compressive loading to adjacent cortical bone (
Schroeder et al., 1981; Schroeder
and Buser, 1989). The significant positive contribution of macrolevel roughness
profile to primary stabilization and long-term fixation of the dental implant has
been demonstrated (Gotfredsen et al., 1995; Buser et al., 1991; Wennerberg et al.,
1995). On the other hand, in the case of peri-implant disease, surface roughness
FIGURE 13.6
The integration of the dental implant occurs by various types at various areas. While the
soft tissue fibers orienting parallel with an intimate contact to the implant shoulder,
osteointegration (desired contact type) or fibro-osseous integration (undesired contact
type) can be achieved in the boneimplant interface.
344 CHAPTER 13 Tissue engineering applications and nanobiomaterials

may cause a disadvantage by increasing the ionic leakage during alveolar bone
loss (Becker et al., 2000
).
The aim of microlevel roughening (110 μm) is to reach a maximum degree
of primary stability (
Wennerberg et al., 1998, 1995; Hansson and Norton, 1999).
Implant surface topography is also modified to orient critical cellular events of
desired cell types on the implant surface. Although better micromechanical
resistance, higher BIC values, and more successful clinical outcomes have been
achieved compared to untreated machined surfaces (Testori et al., 2001
; Conner
et al., 2003;
Cochran et al., 1998; Wennerberg et al., 1998, 1995), further data
are still needed for evidence-based decision-making ( Esposito et al., 2014
).
The methods are acid etch (AE), grit blasting (GB), titanium plasma spray (TPS),
calcium phosphate (CP) coating, and anodizing (
Table 13.1).
AE is applied by immersing implants into acid solutions (H
2
SO
4
, HCl, HF, or
HNO
3
) and heating. Fibrin and osteoblast attachment (Park and Davies, 2000;
Davies, 1998, Trisi et al., 2002), BIC, and osseointegration have been increased
after AE (Wong et al., 1995; Cho and Park, 2003; Cochran et al., 1998, 2002;
Trisi et al., 2003; Novaes et al., 2004; Papalexiou et al., 2004) but it may cause
microcracks that weaken mechanical resistance of titanium (Yokoyama et al.,
2002
). GB is applied by spraying different-sized particles (TiO
2
,Al
2
O
3
,or
CaPO
4
), which are biocompatible, chemically stable, to tita nium surfaces at high
speeds.
TPS is applied by spraying titanium particles into a plasma flame in a highly
heated environment. Assembling and integrating of particles creates a film layer
(3050 μ m thickness and 7 μm roughness depth). Tensile and boneimplant
strength have been increased with the TPS method (
Buser et al., 1991). As a
disadvantage, titanium particles may dissolute, fret, or wear and unwillingly pass
into alveolar bone/peri-implant mucosa (
Urban et al., 2000; Browne and Gregson,
2000; Martini et al., 2003). In terms of clinical success, TPS shows similar results
to sandblasted AE (SLA) (Roccuzzo et al., 2001
) but inferior to plasma-spray
(PS) HA coating (
Taba Junior et al., 2003). Currently, other methods are assumed
to be more advantageous than the TPS method in roughening (
Ong et al., 2004;
Buser et al., 1991).
CP coating aims to mimic inorganic bone phase on titanium surface to develop
osseointegration. Ca and P ion release and HA formation have been shown in the
Table 13.1 Surface Roughness Values of Titanium Implants
Implant Type Roughness Value Implant Type Roughness Value
pTi 0.22 6 0.01 SLActive 1.16 6 0.04
Ti alloy 0.23 6 0.01 PS-HA coating 1.06 6 0.21
TPS 7.01 6 2.09 CP coating 1.83 6 0.64
SLA 1.15 6 0.05
Ti, titanium; TPS, titanium plasma spray; SLA, sandblasted acid-etch; PS, plasma sprayed; CP,
calcium phosphate.
34513.1 Nanobiomaterials and Implant Dentistry

peri-implant area (de Groot et al., 1998; Daculsi et al., 2003). HA enriched from
bioactive proteins might increase attachment and proliferation of cells responsible
from bone formation (Davies, 2003
). There is also a possibility of placing
bioactive proteins/medicines during preparation of CP coating over implant
surfaces for controlled release (
Liu et al., 2005). Several in vivo/clinical studies
have shown accelerated osseointegration around these implants when compared
with untreated machined surfaces (
Morris et al., 2000; Barrere et al., 2003;
Geurs et al., 2002; Jeffcoat et al., 2003; McGlumphy et al., 2003; Le Guehennec
et al., 2008). CP coating techniques are precipitation, sputtering, solgel coating,
electrophoresis, and PS. Possible peeling of the layer is one of the most encoun-
tered problems and may cause BIC failure (Wheeler, 1996; Chang et al., 1999;
Lee et al., 2000; Tinsley et al., 2001). Implant size and bone density are facilitat-
ing factors for this failure (Giavaresi et al., 2003
). In order to prevent dissociation,
providing the similar rate degradation or dissolution of the coating with bone
formation under osteoclastic activity has been suggested. Due to the above-
mentioned reasons, use of HA coatings is limitedly suggested in clinical practice.
However, survival rates of these implants in the long term were found to be
similar compared to other implant systems (
Lee et al., 2000).
13.1.4.1 Surface wettability and chemical modifications
Associated with surface treatment or bulk composition, chemical charge and
composition of surfaces may vary in different implants. The main effect of the
chemical composition is related to wettability. Surface wettability (hydrophilicity)
is a desired property in which the cells, tissues, and biologic fluids may easily
interact (
Lee et al., 2000; Zhao et al., 2005) and the wettability range of all
manufactured surfaces is between 0
(hydrophilic) and 140
(hydrophobic)
(Lee et al., 2000; Bagno and Di Bello, 2004; Giavaresi et al., 2003). It is a critical
factor that effects bone apposition (Streicher et al., 2007; Frosch et al., 2004;
Oh et al., 2005). According to studies, hydrophilic surfaces exhibited better
(Lee et al., 2000
) or similar (Wennerberg et al., 1991; Carlsson et al., 1989 )
osseointegration compared to other dental implant surfaces.
During serial events leadin g to the steps proceeding to o sseointegration that
occur after peripheral bloodimplant interaction (called the Vroman effect)
(
Miller et al., 2006), the hydrophilic surface is more advantageous compared
to hydrophobic due to its protein affinity. Today, a modified, hydrophilic
surface is known as an improving factor for blood clot formation and many
new-generation implants are manufactured with highly developed hydrophilic
surfaces that may present faster osseointegration outcomes compared to others
(
Sawase et al. , 2008).
Based on the wettability concept, fluoride use has emerged as a new trend
in which the dental implant is immersed into a solution with high fluoride
concentration. Then, a microroughened topography with soluble TiF
4
layer is
formed and osteoblast differentiation and osseointegration are enhanced
(
Ellingsen et al., 2004; Cooper et al., 2006). These implants show greater torque
346 CHAPTER 13 Tissue engineering applications and nanobiomaterials

removal values compared to control ones (Ellingsen et al., 2004) they are
regarded as potential candidates for better surfaces and better osseointegration
with addi tion of bioactive substances for the near future. The second implant sys-
tem that was manufactured by depending on wettability concept is the SLActive
implant of Straumann (Straumann AG, Waldenburg, Switzerland). The implant
surface was made by a combination of coarse GB, AE, and nitrogen cleaning.
Then, for hydrophilicity, it was immersed into an isotonic NaCl solution (
Zhao
et al., 2005
). Compared to SLA surfaces, in vivo experiments showed enhanced
wound healing, but BIC was found to be similar (
Schwarz et al., 2007a,b;
Al-Hamdan et al., 2011).
13.1.4.2 Implant surface functionalization with biomolecules
Immobilization of bioactive molecules onto dental implant surfaces has gained
remarkable interest in mimicking the nature of peri-implant bone and mucosa
for an enhanced relationship. The techniques are passive adsorption, silicate
bonding, self-assembling monolayers, and polymeric bioabsorbable thin-film
coatings and by these techniques, growth/differentiation factors can be coate d
(
Bessho et al., 1999; Wikesjo et al., 2002; Tatakis et al., 2002; Stenport et al.,
2003; Boyne and Jones, 2004; Liu et al., 2005). Although promising, there are
still several shortcomings about bio functionalization, such as sta biliz ation
difficulties and burst mediator release. Plasmid gene carriers have been thought
of as a solution to this problem (Huang et al., 2005
) but poor efficacy of the
method in embedding plasmids into cells and uncontrolled syntheses of some
proteins are emerging limitations. Biomimetic coatings also include d rug loading
that plays a role in bone metabolism/remodeling. For this purpose, although
several bioactive substances, such as bisphosphonates and platelet-rich plasma,
have been embedded to implant surfac e and manifest ed promising results in
terms of increasing bone quality (
Josse et al., 2005), their effect has remained
limited (
Meraw and Reeve, 1999; Meraw et al., 1999; Peter et al., 2005;
Le Guehennec et al., 2007; Weibrich et al., 2004).
13.1.5 DENTAL IMPLANTS: PERSPECTIVE FROM PERI-IMPLANT
MUCOSA ATTACHMENT
Despite intensive effort given to the boneimplant interface, achievement of
healthy peri-implant mucosa is also critical to protect the underlying bone
implant interface from bacterial and mechanical attack. For successful soft tissue
attachment, progenitor cells should proliferate and differentiate into epithelial
cells and fibroblasts that are responsible for soft tissue synthesis and adhesion to
the superior part (shoulder) of the implant surface.
When epithelial cell behavior was observed on titanium alloy surfaces, an
ambitious spreading and attachment of cells was detected compared to ceramic
or carbon surfaces (
Jansen et al., 1985; Raisanen et al., 2000). In a low number
34713.1 Nanobiomaterials and Implant Dentistry

of species, HA surfaces demonst rated higher epithelial cell attachment compared
to titanium (Kasten et al., 1990
). Machined surfaces have been highly preferred
for gingival fibroblasts instead of Al
2
O
3
surfaces (Mustafa et al., 1998). On the
contrary, Baharloo et al. (
2005) observed better epithel ial cell attachment
on rougher surfaces such as GB, AE, and SLA. While electropolished and AE
surfaces showed enhanced attachment compared to sandblasted surfaces in some
studies (
Meyle et al., 1993; Hormia et al., 1991), Di Carmine et al.’s (2003) study
findings were otherwise. On the other hand, some authors still defend machined
surfaces that show extended epithelial cell adhesion compared to sandblasted and
TPS surfaces.
Fibroblasts also showed effective proliferation over titanium and AE surfaces
(
Simion et al., 1991), however, TPS or PVC decreased their attachment
(
Sauberlich et al., 1999). Titanium alloy exhibited more rounded fibroblast
morphology and reduced area of attachment compared to pTi and the result
was attributed to minor toxicity of V or Al. Contrarily, Ti nitrite showed more
promising fibroblast attachment results (
Groessner-Schreiber et al., 2003; Kokoti
et al., 2001). Fibroblast attachment was found less on HA surfaces compared
to titanium alloys (Guy et al., 1993
). Commercially available types demonstrated
conflicting fibroblast attachment results. Sandblasted titanium surfaces were found to
be advantageous (
Meyle et al., 1993) or disadvantageous (Kononen et al., 1992;
Hormia and Kononen, 1994) compared to machined and electropolished surfaces.
pTi and Al
2
O
3
surfaces promoted in vivo peri-implant mucosal link consisted
of epithelial and connective tissue attachment structures (
Abrahamsson et al.,
1998
). Epithelial adhesion on Al
2
O
3
surfaces was also reported in vivo (McKinney
et al., 1985
). On the other hand, dental porcelain and gold alloys did not improve
such a connection and, on top of that, soft tissue and bone loss occurred.
The adhesive features and corrosion resistances of the materials might have played
a role in this result. With HA, effective but parallel (not perpendicular) fiber
orientation was seen on the surface (
Comut et al., 2001; Jansen et al., 1991).
Crystal surfaces were also tested to develop peri-implant mucosa attachment but
the outcomes were not satisfactory (Hashimoto et al., 1989
). Zirconia was another
alternative that represented an effective mucosa attachment but with parallel fiber
orientation (
Kohal et al., 2004).
Immunohistochemically, lower peri-implant mucosa inflammation was observed
around the zirconia surface (
Degidi et al., 2006). In vivo at tachme nt properties
around machined and A E implants were not found to be significantly different
(
Abrahamsson et al., 2002). Some authors (Schroeder et al., 1981; Deporter
et al., 1988; Buser et al., 1992) reported solution of the problems related
to parallel orientati on of peri -implant mucosa attachment fibers with porous sur-
faces, although inadequate quality of epithelial and connective tissue attachment
still remains.
Various bioactive molecules, such as fibronectin, vitronectin, type IV
collagen, laminin-1 and -5, were tried to improve soft tissue attachment around
dental implants. Although fibronectin coat ing on machined TPS and HA surfaces
348 CHAPTER 13 Tissue engineering applications and nanobiomaterials

increased fibroblast attachment, epithelial cells showed less affinity to thes e
surfaces (
Dean et al., 1995). However, fibroblasts and epithelial cells both showed
opposite results to laminin-1 modification. Laminin-5 and type IV collagen
improved but vitronectin inhibited epithelial cell adhesion on the surface (
Tamura
et al., 1997; El-Ghannam et al., 1998; Park et al., 1998).
13.1.6 DENTAL IMPLANTS: PERSPECTIVE FROM NANOTECHNOLOGY
13.1.6.1 Nanoevents in extracellular matrix
Living units may have cell-to-cell and cell-to-matrix interactions at the macro-,
micro-, and nanolevel. The micro- and nanolevel interactions may affect the
matrix in structure or chemistry. As nanoscale changes may affect macro- or
microscale events and structures, macro- and microscale changes may cause
to nanolevel modifications. While microlevel features of matrix are rel ated to cell
functions, nanolevel features are associated with cell membrane components
including ion channels, receptors, or integrins (
Webster et al., 1999; Born et al.,
2009; Aznavoorian et al., 1990; Lim and Donahue, 2007; Hamilton and Brunette,
2007). In vivo definition of nanolevel properties is made by the changes in
collagen structure or metabolism (Tzaphlidou, 2005; Vetter et al., 1991; Eppell
et al., 2001). Signaling proteins are also the subjects of nanolevel matrix features.
They are incorporated in matrix and activated by several inducers or events
(Bergers et al., 2000; Ker et al., 2011).
13.1.6.2 Nanofeatures of dental implants
With the advancement in material technology and increasing anticipation to
highest BIC, dental implants with nanolevel roughness (2D or more complex
structures can be created) have been manufactured. There are several defined
nanotechnologic methods that have been applied to implant surfaces: ion beam
deposition, nanoparticle compaction, SLA (
Zhao et al., 2007; Buser et al., 2004),
controlled chemical oxidation (Tavares et al., 2007; de Oliveira et al., 2007), per-
oxide application, anodization, lithography, sinterization (Bitar et al., 2012
),
nanoparticle deposition, and layer-by-layer assembly (
Sher et al., 2010; Zink
et al., 2012; Hu et al., 2012; Kommireddy et al., 2006). With these methods ,
several nanomodified structures involvi ng nanostructures, nanoparticles, nano-
coatings, nanocrystals, nanodots, nanogrooves, nanopits, nanowires, nanoneedles,
nanosheets, nanorods, nanotubes , and nanofibers (Komm ireddy et al., 2006
) have
been obtained. In 2D view, nanofeatures can be classified as isotropic (organized
surface structure) and unisotropic (unorganized surface structure). Nanopits and
nanogrooves are examples of isotropic nanofeatures that can only be applied
to the complex-shaped, screw-type objects. As an example, three times higher
boneimplant interface strength and nearly 40% surface area increase can
be obtained by generation of titanium nanotubes (300 nm) compared to the AE
technique (
Ogawa et al., 2008).
34913.1 Nanobiomaterials and Implant Dentistry

13.1.6.3 Cellular events on nanomodified implant surfaces
Nanolevel modifications have the potential to influence the chemotaxis,
attachment, proliferation, and differentiation properties of MSCs, osteoblasts,
fibroblasts, and epithelial cells (
Figure 13.7). This influence can be realized directly
(cellsurface interaction) or indirectly (effector proteinsurface interaction)
(
Brunette, 1988).
In addition to cell-surface, direct interactions include the relationship between
integrin receptors of cells and surface that is important in signal transmission for
attachment and related cellular activities. Nanodimensions and nanofeatures each
may influence cellular activity (
Cavalcanti-Adam et al., 2007; Andersson et al.,
2003). The same materials with different levels of roughness (microlevel vs nano-
level) may exhibit different MSC and osteoblastic cell attachment and proliferation
(Wan et al., 2005; Webster and Ejiofor, 2004). Numerous in vitro studies have
shown enhancement of MSC and osteoblast attachment by application of nanolevel
modifications such as pits, ridges, coatings, tubes, wires, pores, fibers, etc. onto
implant-related surfaces (Eisenbarth et al., 2007; Webster et al., 2000b, 2001,
FIGURE 13.7
After drilling (vessels are injured) and implant placement, critical events involving
vascularization, protein adsorption, cell attachment, proliferation, differentiation, and
tissue matrix synthesis occur in the boneimplant interface.
350 CHAPTER 13 Tissue engineering applications and nanobiomaterials

2003; Ergun et al., 2007; Balasundaram et al., 2006; Chun et al., 2005; Price et al.,
2003; Lim et al., 2005; Liu et al., 2006; Advincula et al., 2006; Webster and
Smith, 2005; Popat et al., 2007a,b). According to investigations, small amounts of
nanolevel surface changes may differently affect motility, mechanical properties,
and attachment behaviors of MSCs and osteoblastic cells (Hansen et al., 2007
).
The influence on mechanical properties has been attributed to integrin-based
cytoskeleton remodeling or other not yet defined complex biophysical effects.
Some studies exhibited that nanolevel modifications may also restrict cell
attachment (
Dalby et al., 2006). This result has directed investigators to prepare
cell-type speci fic absorbent nanorough surfaces (
Lim et al., 2005, 2007; Cai
et al., 2006). For example, attachment affinity of different cells (osteoblasts,
fibroblasts, or osteoclasts) has been adjusted by modifying surfaces at the nanole-
vel (Price et al., 2003; Webs ter et al., 2001; McManus et al., 2005). In addition to
supporting bone-forming cells, contamination of specific microorganisms has also
been decreased by selective attachment on titanium and zirconia implant surfaces
(Colon et al., 2006
). These results have clinical implications in terms of prevent-
ing fibro-osseous integration and peri-implant diseases in addition to providing
successful connective tissue attachment around the implant.
A positive effect of nanolevel changes to proliferation of osteoblasts and
MSCs has also been demonstrated by in vitro studies (
Zhao et al., 2006; Webster
et al., 2000a; Briggs et al., 2004; Chiesa et al., 2007; Gutwein and Webster, 2004;
Popat et al., 2007a,b). Although controversial, pathways explaining the effect of
nanotechnology to cell proliferation seem to be similar with cell attachment
(Walles et al., 2003
). As the indicators of osteoblastic cell differentiation,
increased levels of Ca mineral content, alkaline phosphatase, bone sialoprotein,
osteopontin, osteocalcin, and runx2 have been demonstrated on nanolevel
modified surfaces by many in vitro investigations (
Webster et al., 1999, 2000a,
2005; Isa et al., 2006; Guo et al., 2007; Liu et al., 2006; de Oliveira et al., 2007;
Bigi et al., 2007; Popat et al., 2007a,b; Dalby et al., 2006; Lim et al., 2005).
Not only cell-surface but also effector proteinsurface interactions are
the subject of nanolevel topographies (indirect interactions, protein-dependent
surface interactions). With respect to this interaction, most studied proteins are
responsible for cell attachment. In several studies, adsorption of such proteins,
fibronectin or vitronectin, have been enhanced with nanolevel rough surface
formation (
Webster et al., 2000b, 2001; Scotchford et al., 2002; Lim et al., 2005).
The degree of nanolevel roughness has also been defined as a determining factor
of cell attachment. Cells cultured on 108 nm pattern surfaces modulated less
attachment than the surfaces with a 58 nm pattern (Cavalcanti-Adam et al., 2007
).
13.1.6.4 Nanotechnology in biomimetic implant surfaces
Critical factors in c reating biomimetic nanosurfaces on an implant are biocom-
patibility, presence/amount of bioactive proteins/drugs, 3D structure, adhesion
ligands mimicking natural tissue matrix, micro - and nanotopog rap hy, and physi-
cal strength (
Vasita and Katti, 2006 ). Differently f rom structure s with higher
35113.1 Nanobiomaterials and Implant Dentistry

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CHAPTER13Tissue engineeringapplications andnanobiomaterials inperiodontology and implantdentistryHuseyin Gencay Keceli1, Abdullah Cevdet Akman1, Cem Bayram2andRahime Meral Nohutcu11Periodontology Department, Faculty of Dentistry, Hacettepe University, Ankara, Turkey2Hacettepe University, Advanced Technologies Application and Research Center Beytepe,Ankara, Turkey13.1 NANOBIOMATERIALS AND IMPLANT DENTISTRYDepending on tooth loss due to developmental anomalies, caries, periodontaldisease, or trauma, dentition needs therapeutic modalities to regain its aestheticand functional properties. Conventional therapy involving fixed or removabledentures may have indispensable inadequacies such as insufficient occlusalactivity, ongoing alveolar bone loss, limited material biocompatibility andstrength. Secondary problems including tooth fracture and dental caries may alsooccur (Davarpanah et al., 2000).From the 1980s, dental implants have been presented as a revolution forsupporting the functional restorations and have been put into routine clinical dentalpractice. Implant installation has been rega rded as a treatment of choice for edentu-lous patients because of its biocompatibility and stability (Douglass and Watson,2002; Douglass et al., 2002). Until today, various implant types like “transosteal,”“subperiosteal,” and “endosteal” have emerged (Iacono, 2000)(Figure 13.1).Today, the most reliable one in clinical utilization is the endosteal type because ofits superiority in surgica l morbidity, force distribution, and aesthetics. Clinically,implant selection needs experience and thorough evaluation, considering theparameters of bone dimensions and quality (Iacono, 2000)(Figure 13.2).Commonly encountered situations related to implant failure could be summarizedas insufficient cell proliferation at the implant surface, cell death at the vicinity ofimplant due to erosion, and debris caused by the rough surface, and loosening and337Nanobiomaterials in Dentistry. DOI: http://dx.doi.org/10.1016/B978-0-323-42867-5.00013-8© 2016 Elsevier Inc. All rights reserved. fractures which originate from the load and stress imbalance between the implantand surrounding tissue. From this point of view, induction of bone formationaround the implant and a rapid integration to juxtaposed bone is required toovercome these problems, so the surface of the implant must be appropriate forosteoblast colonization and bone tissue synthesis.In this part, to understand the relationship between nanotechn ology and dentalimplants, critical features of the tissues surrounding the dental implants andunderlying mechanisms related to the osseointegration concept will be reviewedfirst. Then, from macro- to nanolevel, the properties of the dental implant surfacesand their interactions with these tissues will be evaluated. This text also aims toinform the readers of recent techniques aimed at enhancing bone formation andimproving osseointegration.FIGURE 13.1Types of dental implants.FIGURE 13.2In addition to experience and thorough evaluation, successful implant treatment can beachieved by considering the parameters of bone dimensions, quality, and functional needs.338 CHAPTER 13 Tissue engineering applications and nanobiomaterials 13.1.1 DENTAL IMPLANTS: PERSPECTIVEFROM SURROUNDING TISSUESSoft tissue around dental implants is a specialized mucosa and named the“peri-implant mucosa” that represents similar properties to periodontal tissues.Peri-implant mucosa consists of epithelium and connective tissue layers and itsmain function is to protect the underlying tissues from mechanical and bacterialattacks (Listgarten and Lai, 1975; Swope and James, 1981). According to itslocalization over the implant surface, epithelium has three portions, oral, sulcular,and junctional (Figure 13.3). The height of sulcular epithelium represents thedepth of the peri-implant sulcus, and depends on the thickness of keratinizedtissue overlying the alveolar bone. For optimal health conditions, values from oneto three are suggested. The distance between the top and bottom of junctionalepithelium is 11.5 mm (Berglundh et al., 1991). The tip of peri-implant mucosais less vascularized and, therefore, requires gent le handling during surgery(Figure 13.4).Collagen (mainly type I) is a fundamental component of the connective tissue(Chavrier and Couble, 1999). Differing from gingival mucosa around natural teeth,peri-implant mucosa has a lower number of fibroblast cells and rather than perpen-dicular, collagen fibers lie parallel to the implant surface (Berglundh et al., 1991).The interface of connective tissue and implant is called the connective tissueattachment and its ideal height is 1.52mm (Berglundh et al., 1994). When softFIGURE 13.3The main parts of an endosteal implant and its surrounding soft (peri-implant mucosa)and hard (alveolar bone) tissues.33913.1 Nanobiomaterials and Implant Dentistry tissue height is below this level, bone resorption may occur after implantplacement to establish the desired amount of mucosa thickness (Berglundh andLindhe, 1996). If the soft tissue is too thick, a deep peri-implant sulcus may occurafter implant placement that impairs plaque removal (Figure 13.5).Alveolar bone surrounding the implant is comprised of organic and inorganicmatrices. The composition of organic matrix is collagenous and noncollagenousFIGURE 13.4The tip of peri-implant mucosa is less vascularized and, therefore, requires gentlehandling during surgery. Note the whitish color of peri-implant mucosa easily affected byinappropriate cap placement.FIGURE 13.5Peri-implant tissue thickness is an important factor for maintaining the health ofsurrounding tissues. A deep peri-implant sulcus may impair plaque removal and causeperi-implant disease.340 CHAPTER 13 Tissue engineering applications and nanobiomaterials proteins, whereas inorganic matrix is comprised of ions (mainly Ca and P) andhydroxyapatite (HA) structure s. Alveolar bone encounters chewing loads, protectsthe nervous system, and contributes to mineral homeostasis. The primary celltype in the bone is the osteoblast which participates in bone formation, organicmatrix synthesis, and inorganic matrix mineralization. Bone-lining cells are thesecond group that covers bone tissue with no synthetic function. Osteocytes arethe third group, trapped inside the synthesized bone matrix, providing communi-cation to the other bone cells with their processes and increasing the contact areabetween cells and organic matrix. They also play a role in systemic Ca hemostasisand make signal transduction during mechanical forces. The fourth group, osteo-clasts, are bone cells responsible for resorptive activity that is maintained withformative process in a balance and activated in case of a pathologic event such asperiodontal disease, trauma, etc. These cells are multinuc leated and originatefrom progenitor cells of the hematopoietic system. Osteoprogenitor cells are thefifth group and migrate to the injured site and differentiate into osteoblasts duringbone formation. Two types of osteoprogenitor cells are present, inducible anddetermined. Determined cells can reside in endosteum, periosteum, or bone mar-row and are capable of proliferating and differentiating into osteoblasts. Induciblecells are commonly known as mesenchymal stem cells (MSCs). Although lower,the submucosa of implant-related tissues (gi ngiva, periosteum, alveolar bone) alsoincorporates MSCs. They have two specific properties; being capable of renewingthemselves even after extended inactive periods and being stimulated to synthe-size specific tissues/organs by inducing their differentiation and other specialfunctions. Even though the main origin of MSCs is bone marrow (Friedensteinet al., 1968), they are also present and can be isolated from various other tissues(Friedenstein et al., 1968; Zannettino et al., 2008; Wickham et al., 2003;Hoogduijn et al., 2007; Jo et al., 2007; He et al., 2007; Oh et al., 2008;Morganstein et al., 2010; Marinucci et al., 2010; Lepski et al., 2010; Engler et al.,2006; Chivu et al., 2009; Liu et al., 2007).Before implant placement, the amount of residual alve olar bone maycomplicate the therapy and, thus, utilization of bone substitutes or guidedbone-regeneration techniques might be needed. Following application of theseapproaches and/or placement of dental implants, three main bone-related eventsmay occur: osteogenesis, osteoinduction, and os teoconduction. Osteogenesis isthe natural formation activity of the bone that occurs in the presence of a highnumber of vital osteoblasts/osteop rogenitor cells inside the bone cavity or at theboneimplant interface. Autogenous bone grafts and bone marrow grafts arewell-known examples of treatments providing osteogenesis. Osteoinductionis the process that bioactive proteins enhance proliferation and differentiation ofcells responsible from bone synthesis. These bioactive proteins related toosteoind uction, commonly known as growth/differentiation factors, mainly residein bone matrix and their synthesis can be externally induced for enhancingosteoind uction and implant osseointegration (Giannob ile and Somerman, 2003;Reynolds et al., 2003).34113.1 Nanobiomaterials and Implant Dentistry 13.1.2 DENTAL IMPLANTS: PERSPECTIVEFROM OSSEOINTEGRATIONThere are two concepts carrying priority in survival and success of implant treat-ment, primary stability and osseointegration. Primary stability is defined asimmediate mechanical anchorage of the implant to surrounding alveolar bone.Bone quantity, quality, and implant surface characteristics have been indicated asthe main factors influencing primary stability (Roos et al., 1997). The other, butoverriding, phenomenon is osseointegration which is defined as the functionalbinding between surfaces of dental implant and circumjacent living alveolar bonewithout any soft tissue interference and is a unique and multistep process(Branemark et al., 1995). These steps are reviewed below.After drilling, vessels of trabecular bone are injured and the relationshipbetween implant and its adjacent tissues begins with titanium surfacevascularunit contact (Figure 13.7). With this contact, plasma proteins inside the bloodare absorbed by the surface in a few minutes, thrombocytes are activated andclotting occurs with thrombus and fibrin formation. During clotting, plasmaproteins modify the titanium surface and several cell types move and attach tothis modified interface by their integrin receptors. Cell attachment is promotedby cell-binding RGD domains (Arg-Gly-Asp) of adsorption proteins such asvitronectin and fibronectin. Fibronectin/vitronectin is locate d on membranes ofmany cell types and the RGD domain interacts with extensions of these proteins(Balasundaram et al., 2006).Attraction of MSCs to the biological activity area is one of the most criticalfactors to achieve bone synthesis by their proliferative activity and differentiation(Agis et al., 2009; Vogel et al., 2006). These activities are induced by growth/differentiation factors involving vascular endothelial growth factor (Fiedler et al.,2005), epidermal growth factor (EGF) (Ozaki et al., 2007; Kuznetsov et al., 1997),platelet-derived growth factor (PDGF) (Mishima and Lotz, 2008; Ozaki et al., 2007),transforming growth factor (TGF-β)(Mishima and Lotz, 2008; Jian et al., 2006), andbone morphogenetic proteins (BMPs) (Mishima and Lotz, 2008; Fiedler et al., 2005).Moreover, fibrin is a 3D healing tissue matrix composed of bioactive molecules/factors that are slowly released to the injury site and enhance chemotaxis andgrowth of MSCs (Catelas et al., 2006, 2008; Wong et al., 2003; Mosesson, 2005;Rock et al., 2006). Under the effect of growth/differentiation factors within afibrin matrix, MSCs are also capable of differentiating into osteoblastic cells andwith this process, bone formation is provided on the boneimplant interface.All steps of cellular activity are influenced and manipulated by surface features ofdental implants.After a few weeks, primary stability leaves its place to living boneimplantcontact (BIC) by achievement of bone formation with secondary mechanisms tak-ing the process into osseointegration (Branemark et al., 1969, 1983; Linder et al.,1983). When achieved and able to be maintained long term, it is known as thekey factor of predictability in front of constant chewing loads (Adell et al., 1990).342 CHAPTER 13 Tissue engineering applications and nanobiomaterials Besides new bone formation, hematoma and necrotic bone particles are movedaway from the environment by macrophages and osteoclasts residing inside thegranulation tissue. To maintain their formative activity, osteoblasts are attached tothe surface. After covering the whole implant surface with de novo bone andcompletion of the formation process, osteoblasts transform into osteocytes thathave their own surrounding matrix and products. The first type of bone formedover the implant is woven bone that transforms into more organized and denselamellar bone by remodeling over a few months (Adell et al., 1990; Jan Lindheand Lang, 2008). At this step, the connection between alveolar bone and implantis at its “weakest” (Jan Lindhe and Lang, 2008).If any location of implant is surrounded by fibrous tissue owing to fibroblastproliferation, the process is called fibro-osseo us integration, which is considereda negative outcome (Davies, 2003). During this process, MSCs differentiate intofibroblastic cells instead of osteoblasts, and fibroblasts produce a collagen capsulepreventing direct BIC during integration. Fibrous soft tissue may cause animproper fixation that later leads to a probable implant failure and also inhibitsnew bone formation indirectly by affecting the osteoblast/osteoclast balance(Hobkirk, 1983).13.1.3 DENTAL IMPLANTS: PERSPECTIVE FROM MATERIALSPure titanium (pTi) or titanium alloys (Ti6Al4V) are the most widely used andhighly biocompatible materials. Alloys have higher fatigue and yield strengthand they are comprised of fifth-grade titanium (Hobkirk, 1983). When the surfaceof the titanium is exposed to air, a titanium oxide layer providing direct boneimplant connection occurs (Oshida, 2006).Ceramic materials have also been used as implant materials. Thirty years ago,aluminum oxides in polycrystalline (PC; generic name: Frialit-1) and singlecrystal (AO; generic name: Kyocera) forms were used in clinical practice.Nowadays, the interest in implant surface material technology assembles onanother ceramic, zirconia (ZrO2). In dentistry, zirconia is not a new material andhas been already used in crown and bridge fabrication and successful outcomeswere reported after testing in vivo and in clinical models (Akagawa et al., 1998;Kohal et al., 2004; Oliva et al., 2007).13.1.4 DENTAL IMPLANTS: PERSPECTIVEFROM SURFACE PROPERTIESImplant surfaces providing the nearest contact with adjacent bone are desired toenhance osseointegration (Stanford and Brand, 1999)(Figure 13.6). Macro- andmicrolevel features residing over surface structure of dental implants are describedas surface topography and these features determine the micromechanical relation-ship of implant with surr ounding bone. Surface roughening is the best-known34313.1 Nanobiomaterials and Implant Dentistry method to increase surface area of BIC, which may lead to obtaining greater areato encountering the forces directed at the boneimplant interface (Wennerberget al., 1997; Hansson, 1999, 2000; Buser et al., 1991). Though surface roughnessprovides better clinical and histologic results, it is still not certain to think of theroughness as the single key of success (Wennerberg and Albrektsson, 2000).On the other hand, roughness is also a confounding and complicating factor inmaking comparisons between different dental implant systems.Features of implant surface topography can be classified according to themodifications in macro-, micro- or nanosized level. Macrolevel is topologic detail(1 mm to 10 μm) that can be set by creating threaded screws, solid body press-fitdesigns, and sinter ing technologies. Since alveolar bone responds favorably tocompressive stresses instead of shear forces (Stanford, 1999), most of the threaddesigns have been created to reduce shear forces at the thread tip and transmitcompressive loading to adjacent cortical bone (Schroeder et al., 1981; Schroederand Buser, 1989). The significant positive contribution of macrolevel roughnessprofile to primary stabilization and long-term fixation of the dental implant hasbeen demonstrated (Gotfredsen et al., 1995; Buser et al., 1991; Wennerberg et al.,1995). On the other hand, in the case of peri-implant disease, surface roughnessFIGURE 13.6The integration of the dental implant occurs by various types at various areas. While thesoft tissue fibers orienting parallel with an intimate contact to the implant shoulder,osteointegration (desired contact type) or fibro-osseous integration (undesired contacttype) can be achieved in the boneimplant interface.344 CHAPTER 13 Tissue engineering applications and nanobiomaterials may cause a disadvantage by increasing the ionic leakage during alveolar boneloss (Becker et al., 2000).The aim of microlevel roughening (110 μm) is to reach a maximum degreeof primary stability (Wennerberg et al., 1998, 1995; Hansson and Norton, 1999).Implant surface topography is also modified to orient critical cellular events ofdesired cell types on the implant surface. Although better micromechanicalresistance, higher BIC values, and more successful clinical outcomes have beenachieved compared to untreated machined surfaces (Testori et al., 2001; Conneret al., 2003;Cochran et al., 1998; Wennerberg et al., 1998, 1995), further dataare still needed for evidence-based decision-making ( Esposito et al., 2014).The methods are acid etch (AE), grit blasting (GB), titanium plasma spray (TPS),calcium phosphate (CP) coating, and anodizing (Table 13.1).AE is applied by immersing implants into acid solutions (H2SO4, HCl, HF, orHNO3) and heating. Fibrin and osteoblast attachment (Park and Davies, 2000;Davies, 1998, Trisi et al., 2002), BIC, and osseointegration have been increasedafter AE (Wong et al., 1995; Cho and Park, 2003; Cochran et al., 1998, 2002;Trisi et al., 2003; Novaes et al., 2004; Papalexiou et al., 2004) but it may causemicrocracks that weaken mechanical resistance of titanium (Yokoyama et al.,2002). GB is applied by spraying different-sized particles (TiO2,Al2O3,orCaPO4), which are biocompatible, chemically stable, to tita nium surfaces at highspeeds.TPS is applied by spraying titanium particles into a plasma flame in a highlyheated environment. Assembling and integrating of particles creates a film layer(3050 μ m thickness and 7 μm roughness depth). Tensile and boneimplantstrength have been increased with the TPS method (Buser et al., 1991). As adisadvantage, titanium particles may dissolute, fret, or wear and unwillingly passinto alveolar bone/peri-implant mucosa (Urban et al., 2000; Browne and Gregson,2000; Martini et al., 2003). In terms of clinical success, TPS shows similar resultsto sandblasted AE (SLA) (Roccuzzo et al., 2001) but inferior to plasma-spray(PS) HA coating (Taba Junior et al., 2003). Currently, other methods are assumedto be more advantageous than the TPS method in roughening (Ong et al., 2004;Buser et al., 1991).CP coating aims to mimic inorganic bone phase on titanium surface to developosseointegration. Ca and P ion release and HA formation have been shown in theTable 13.1 Surface Roughness Values of Titanium ImplantsImplant Type Roughness Value Implant Type Roughness ValuepTi 0.22 6 0.01 SLActive 1.16 6 0.04Ti alloy 0.23 6 0.01 PS-HA coating 1.06 6 0.21TPS 7.01 6 2.09 CP coating 1.83 6 0.64SLA 1.15 6 0.05Ti, titanium; TPS, titanium plasma spray; SLA, sandblasted acid-etch; PS, plasma sprayed; CP,calcium phosphate.34513.1 Nanobiomaterials and Implant Dentistry peri-implant area (de Groot et al., 1998; Daculsi et al., 2003). HA enriched frombioactive proteins might increase attachment and proliferation of cells responsiblefrom bone formation (Davies, 2003). There is also a possibility of placingbioactive proteins/medicines during preparation of CP coating over implantsurfaces for controlled release (Liu et al., 2005). Several in vivo/clinical studieshave shown accelerated osseointegration around these implants when comparedwith untreated machined surfaces (Morris et al., 2000; Barrere et al., 2003;Geurs et al., 2002; Jeffcoat et al., 2003; McGlumphy et al., 2003; Le Guehennecet al., 2008). CP coating techniques are precipitation, sputtering, solgel coating,electrophoresis, and PS. Possible peeling of the layer is one of the most encoun-tered problems and may cause BIC failure (Wheeler, 1996; Chang et al., 1999;Lee et al., 2000; Tinsley et al., 2001). Implant size and bone density are facilitat-ing factors for this failure (Giavaresi et al., 2003). In order to prevent dissociation,providing the similar rate degradation or dissolution of the coating with boneformation under osteoclastic activity has been suggested. Due to the above-mentioned reasons, use of HA coatings is limitedly suggested in clinical practice.However, survival rates of these implants in the long term were found to besimilar compared to other implant systems (Lee et al., 2000).13.1.4.1 Surface wettability and chemical modificationsAssociated with surface treatment or bulk composition, chemical charge andcomposition of surfaces may vary in different implants. The main effect of thechemical composition is related to wettability. Surface wettability (hydrophilicity)is a desired property in which the cells, tissues, and biologic fluids may easilyinteract (Lee et al., 2000; Zhao et al., 2005) and the wettability range of allmanufactured surfaces is between 0(hydrophilic) and 140(hydrophobic)(Lee et al., 2000; Bagno and Di Bello, 2004; Giavaresi et al., 2003). It is a criticalfactor that effects bone apposition (Streicher et al., 2007; Frosch et al., 2004;Oh et al., 2005). According to studies, hydrophilic surfaces exhibited better(Lee et al., 2000) or similar (Wennerberg et al., 1991; Carlsson et al., 1989 )osseointegration compared to other dental implant surfaces.During serial events leadin g to the steps proceeding to o sseointegration thatoccur after peripheral bloodimplant interaction (called the Vroman effect)(Miller et al., 2006), the hydrophilic surface is more advantageous comparedto hydrophobic due to its protein affinity. Today, a modified, hydrophilicsurface is known as an improving factor for blood clot formation and manynew-generation implants are manufactured with highly developed hydrophilicsurfaces that may present faster osseointegration outcomes compared to others(Sawase et al. , 2008).Based on the wettability concept, fluoride use has emerged as a new trendin which the dental implant is immersed into a solution with high fluorideconcentration. Then, a microroughened topography with soluble TiF4layer isformed and osteoblast differentiation and osseointegration are enhanced(Ellingsen et al., 2004; Cooper et al., 2006). These implants show greater torque346 CHAPTER 13 Tissue engineering applications and nanobiomaterials removal values compared to control ones (Ellingsen et al., 2004) they areregarded as potential candidates for better surfaces and better osseointegrationwith addi tion of bioactive substances for the near future. The second implant sys-tem that was manufactured by depending on wettability concept is the SLActiveimplant of Straumann (Straumann AG, Waldenburg, Switzerland). The implantsurface was made by a combination of coarse GB, AE, and nitrogen cleaning.Then, for hydrophilicity, it was immersed into an isotonic NaCl solution (Zhaoet al., 2005). Compared to SLA surfaces, in vivo experiments showed enhancedwound healing, but BIC was found to be similar (Schwarz et al., 2007a,b;Al-Hamdan et al., 2011).13.1.4.2 Implant surface functionalization with biomoleculesImmobilization of bioactive molecules onto dental implant surfaces has gainedremarkable interest in mimicking the nature of peri-implant bone and mucosafor an enhanced relationship. The techniques are passive adsorption, silicatebonding, self-assembling monolayers, and polymeric bioabsorbable thin-filmcoatings and by these techniques, growth/differentiation factors can be coate d(Bessho et al., 1999; Wikesjo et al., 2002; Tatakis et al., 2002; Stenport et al.,2003; Boyne and Jones, 2004; Liu et al., 2005). Although promising, there arestill several shortcomings about bio functionalization, such as sta biliz ationdifficulties and burst mediator release. Plasmid gene carriers have been thoughtof as a solution to this problem (Huang et al., 2005) but poor efficacy of themethod in embedding plasmids into cells and uncontrolled syntheses of someproteins are emerging limitations. Biomimetic coatings also include d rug loadingthat plays a role in bone metabolism/remodeling. For this purpose, althoughseveral bioactive substances, such as bisphosphonates and platelet-rich plasma,have been embedded to implant surfac e and manifest ed promising results interms of increasing bone quality (Josse et al., 2005), their effect has remainedlimited (Meraw and Reeve, 1999; Meraw et al., 1999; Peter et al., 2005;Le Guehennec et al., 2007; Weibrich et al., 2004).13.1.5 DENTAL IMPLANTS: PERSPECTIVE FROM PERI-IMPLANTMUCOSA ATTACHMENTDespite intensive effort given to the boneimplant interface, achievement ofhealthy peri-implant mucosa is also critical to protect the underlying boneimplant interface from bacterial and mechanical attack. For successful soft tissueattachment, progenitor cells should proliferate and differentiate into epithelialcells and fibroblasts that are responsible for soft tissue synthesis and adhesion tothe superior part (shoulder) of the implant surface.When epithelial cell behavior was observed on titanium alloy surfaces, anambitious spreading and attachment of cells was detected compared to ceramicor carbon surfaces (Jansen et al., 1985; Raisanen et al., 2000). In a low number34713.1 Nanobiomaterials and Implant Dentistry of species, HA surfaces demonst rated higher epithelial cell attachment comparedto titanium (Kasten et al., 1990). Machined surfaces have been highly preferredfor gingival fibroblasts instead of Al2O3surfaces (Mustafa et al., 1998). On thecontrary, Baharloo et al. (2005) observed better epithel ial cell attachmenton rougher surfaces such as GB, AE, and SLA. While electropolished and AEsurfaces showed enhanced attachment compared to sandblasted surfaces in somestudies (Meyle et al., 1993; Hormia et al., 1991), Di Carmine et al.’s (2003) studyfindings were otherwise. On the other hand, some authors still defend machinedsurfaces that show extended epithelial cell adhesion compared to sandblasted andTPS surfaces.Fibroblasts also showed effective proliferation over titanium and AE surfaces(Simion et al., 1991), however, TPS or PVC decreased their attachment(Sauberlich et al., 1999). Titanium alloy exhibited more rounded fibroblastmorphology and reduced area of attachment compared to pTi and the resultwas attributed to minor toxicity of V or Al. Contrarily, Ti nitrite showed morepromising fibroblast attachment results (Groessner-Schreiber et al., 2003; Kokotiet al., 2001). Fibroblast attachment was found less on HA surfaces comparedto titanium alloys (Guy et al., 1993). Commercially available types demonstratedconflicting fibroblast attachment results. Sandblasted titanium surfaces were found tobe advantageous (Meyle et al., 1993) or disadvantageous (Kononen et al., 1992;Hormia and Kononen, 1994) compared to machined and electropolished surfaces.pTi and Al2O3surfaces promoted in vivo peri-implant mucosal link consistedof epithelial and connective tissue attachment structures (Abrahamsson et al.,1998). Epithelial adhesion on Al2O3surfaces was also reported in vivo (McKinneyet al., 1985). On the other hand, dental porcelain and gold alloys did not improvesuch a connection and, on top of that, soft tissue and bone loss occurred.The adhesive features and corrosion resistances of the materials might have playeda role in this result. With HA, effective but parallel (not perpendicular) fiberorientation was seen on the surface (Comut et al., 2001; Jansen et al., 1991).Crystal surfaces were also tested to develop peri-implant mucosa attachment butthe outcomes were not satisfactory (Hashimoto et al., 1989). Zirconia was anotheralternative that represented an effective mucosa attachment but with parallel fiberorientation (Kohal et al., 2004).Immunohistochemically, lower peri-implant mucosa inflammation was observedaround the zirconia surface (Degidi et al., 2006). In vivo at tachme nt propertiesaround machined and A E implants were not found to be significantly different(Abrahamsson et al., 2002). Some authors (Schroeder et al., 1981; Deporteret al., 1988; Buser et al., 1992) reported solution of the problems relatedto parallel orientati on of peri -implant mucosa attachment fibers with porous sur-faces, although inadequate quality of epithelial and connective tissue attachmentstill remains.Various bioactive molecules, such as fibronectin, vitronectin, type IVcollagen, laminin-1 and -5, were tried to improve soft tissue attachment arounddental implants. Although fibronectin coat ing on machined TPS and HA surfaces348 CHAPTER 13 Tissue engineering applications and nanobiomaterials increased fibroblast attachment, epithelial cells showed less affinity to thes esurfaces (Dean et al., 1995). However, fibroblasts and epithelial cells both showedopposite results to laminin-1 modification. Laminin-5 and type IV collagenimproved but vitronectin inhibited epithelial cell adhesion on the surface (Tamuraet al., 1997; El-Ghannam et al., 1998; Park et al., 1998).13.1.6 DENTAL IMPLANTS: PERSPECTIVE FROM NANOTECHNOLOGY13.1.6.1 Nanoevents in extracellular matrixLiving units may have cell-to-cell and cell-to-matrix interactions at the macro-,micro-, and nanolevel. The micro- and nanolevel interactions may affect thematrix in structure or chemistry. As nanoscale changes may affect macro- ormicroscale events and structures, macro- and microscale changes may causeto nanolevel modifications. While microlevel features of matrix are rel ated to cellfunctions, nanolevel features are associated with cell membrane componentsincluding ion channels, receptors, or integrins (Webster et al., 1999; Born et al.,2009; Aznavoorian et al., 1990; Lim and Donahue, 2007; Hamilton and Brunette,2007). In vivo definition of nanolevel properties is made by the changes incollagen structure or metabolism (Tzaphlidou, 2005; Vetter et al., 1991; Eppellet al., 2001). Signaling proteins are also the subjects of nanolevel matrix features.They are incorporated in matrix and activated by several inducers or events(Bergers et al., 2000; Ker et al., 2011).13.1.6.2 Nanofeatures of dental implantsWith the advancement in material technology and increasing anticipation tohighest BIC, dental implants with nanolevel roughness (2D or more complexstructures can be created) have been manufactured. There are several definednanotechnologic methods that have been applied to implant surfaces: ion beamdeposition, nanoparticle compaction, SLA (Zhao et al., 2007; Buser et al., 2004),controlled chemical oxidation (Tavares et al., 2007; de Oliveira et al., 2007), per-oxide application, anodization, lithography, sinterization (Bitar et al., 2012),nanoparticle deposition, and layer-by-layer assembly (Sher et al., 2010; Zinket al., 2012; Hu et al., 2012; Kommireddy et al., 2006). With these methods ,several nanomodified structures involvi ng nanostructures, nanoparticles, nano-coatings, nanocrystals, nanodots, nanogrooves, nanopits, nanowires, nanoneedles,nanosheets, nanorods, nanotubes , and nanofibers (Komm ireddy et al., 2006) havebeen obtained. In 2D view, nanofeatures can be classified as isotropic (organizedsurface structure) and unisotropic (unorganized surface structure). Nanopits andnanogrooves are examples of isotropic nanofeatures that can only be appliedto the complex-shaped, screw-type objects. As an example, three times higherboneimplant interface strength and nearly 40% surface area increase canbe obtained by generation of titanium nanotubes (300 nm) compared to the AEtechnique (Ogawa et al., 2008).34913.1 Nanobiomaterials and Implant Dentistry 13.1.6.3 Cellular events on nanomodified implant surfacesNanolevel modifications have the potential to influence the chemotaxis,attachment, proliferation, and differentiation properties of MSCs, osteoblasts,fibroblasts, and epithelial cells (Figure 13.7). This influence can be realized directly(cellsurface interaction) or indirectly (effector proteinsurface interaction)(Brunette, 1988).In addition to cell-surface, direct interactions include the relationship betweenintegrin receptors of cells and surface that is important in signal transmission forattachment and related cellular activities. Nanodimensions and nanofeatures eachmay influence cellular activity (Cavalcanti-Adam et al., 2007; Andersson et al.,2003). The same materials with different levels of roughness (microlevel vs nano-level) may exhibit different MSC and osteoblastic cell attachment and proliferation(Wan et al., 2005; Webster and Ejiofor, 2004). Numerous in vitro studies haveshown enhancement of MSC and osteoblast attachment by application of nanolevelmodifications such as pits, ridges, coatings, tubes, wires, pores, fibers, etc. ontoimplant-related surfaces (Eisenbarth et al., 2007; Webster et al., 2000b, 2001,FIGURE 13.7After drilling (vessels are injured) and implant placement, critical events involvingvascularization, protein adsorption, cell attachment, proliferation, differentiation, andtissue matrix synthesis occur in the boneimplant interface.350 CHAPTER 13 Tissue engineering applications and nanobiomaterials 2003; Ergun et al., 2007; Balasundaram et al., 2006; Chun et al., 2005; Price et al.,2003; Lim et al., 2005; Liu et al., 2006; Advincula et al., 2006; Webster andSmith, 2005; Popat et al., 2007a,b). According to investigations, small amounts ofnanolevel surface changes may differently affect motility, mechanical properties,and attachment behaviors of MSCs and osteoblastic cells (Hansen et al., 2007).The influence on mechanical properties has been attributed to integrin-basedcytoskeleton remodeling or other not yet defined complex biophysical effects.Some studies exhibited that nanolevel modifications may also restrict cellattachment (Dalby et al., 2006). This result has directed investigators to preparecell-type speci fic absorbent nanorough surfaces (Lim et al., 2005, 2007; Caiet al., 2006). For example, attachment affinity of different cells (osteoblasts,fibroblasts, or osteoclasts) has been adjusted by modifying surfaces at the nanole-vel (Price et al., 2003; Webs ter et al., 2001; McManus et al., 2005). In addition tosupporting bone-forming cells, contamination of specific microorganisms has alsobeen decreased by selective attachment on titanium and zirconia implant surfaces(Colon et al., 2006). These results have clinical implications in terms of prevent-ing fibro-osseous integration and peri-implant diseases in addition to providingsuccessful connective tissue attachment around the implant.A positive effect of nanolevel changes to proliferation of osteoblasts andMSCs has also been demonstrated by in vitro studies (Zhao et al., 2006; Websteret al., 2000a; Briggs et al., 2004; Chiesa et al., 2007; Gutwein and Webster, 2004;Popat et al., 2007a,b). Although controversial, pathways explaining the effect ofnanotechnology to cell proliferation seem to be similar with cell attachment(Walles et al., 2003). As the indicators of osteoblastic cell differentiation,increased levels of Ca mineral content, alkaline phosphatase, bone sialoprotein,osteopontin, osteocalcin, and runx2 have been demonstrated on nanolevelmodified surfaces by many in vitro investigations (Webster et al., 1999, 2000a,2005; Isa et al., 2006; Guo et al., 2007; Liu et al., 2006; de Oliveira et al., 2007;Bigi et al., 2007; Popat et al., 2007a,b; Dalby et al., 2006; Lim et al., 2005).Not only cell-surface but also effector proteinsurface interactions arethe subject of nanolevel topographies (indirect interactions, protein-dependentsurface interactions). With respect to this interaction, most studied proteins areresponsible for cell attachment. In several studies, adsorption of such proteins,fibronectin or vitronectin, have been enhanced with nanolevel rough surfaceformation (Webster et al., 2000b, 2001; Scotchford et al., 2002; Lim et al., 2005).The degree of nanolevel roughness has also been defined as a determining factorof cell attachment. Cells cultured on 108 nm pattern surfaces modulated lessattachment than the surfaces with a 58 nm pattern (Cavalcanti-Adam et al., 2007).13.1.6.4 Nanotechnology in biomimetic implant surfacesCritical factors in c reating biomimetic nanosurfaces on an implant are biocom-patibility, presence/amount of bioactive proteins/drugs, 3D structure, adhesionligands mimicking natural tissue matrix, micro - and nanotopog rap hy, and physi-cal strength (Vasita and Katti, 2006 ). Differently f rom structure s with higher35113.1 Nanobiomaterials and Implant Dentistry magnifications, nanosurfaces do not absorb proteins during their interac tion withcarrier fluids (Webster et al., 1999, 2000b, 2001). Specific pr otei n interfaces areformed between cells and surface mate rial. Instead of an unexpecte d intense orinflammatory event, the surface selectively adsorbs the cell type that providesdesired tissue synthesis. Nevertheless, nonoptimal interactions such as unwantedcell adhesion and changes in cell sta te may occur. To prevent such events,isolative biocompatible coatings, such as artificial organic matrix or diamondslike carbon layer, can be generated on the impla nt surface. Artificial organicmatrix can also be s olely used in in vitro and in vivo experiments that shouldmimic alveolar bone by having a nanofibrillar structure containing collagenousand noncollagenous proteins (glycoproteins, proteoglycans) in addition tomineral phase of bone mainly consisting of HA. Biocompatibility, bioactivity,degradability, corrosion resistance, surface/volume r atio, por osity, modifiability,and physical strength are the importan t genera l criteria (Murugan andRamakrishna, 2007). Acellular t issue matrix and hydrogels (natural/synthetic)are most used artificial matrices for this purpose (Walles et al., 2003). Synt heticmatrix has several advantages such as well-defined structure, productionpossibility of specific biomolecule a dmin istration to inert structures, w hich mayprovide the desired nanoactivity (Mahoney and Anseth, 2006). Boundi ng or freeembedding techniques can be applied to administer biomolecules (Lienemannet al., 2012). Proteinprotein interactions and protein folding can also createan organized network inside the hydrogels (Shen et al., 2006). Biom ole culeingredients may respond to stimulations and then take a cont rolled responsibilityin bioactive p rocesse s. Simila r to natural tissues, chemical c rosslinks can besolved with proteolys is to permit cell proliferation on the organized network(Lutolf et al., 2003; Adelow et al., 2008; Kraehenbuehl et al., 2008). With theaddition of fibrin-like structures or DNA components, bioactive substancerelease can also be controlled (Ehrbar e t al., 2007; Murakami a nd Maeda, 2005;Peled et al., 2 007).13.1.6.5 Implant surface nanofunctionalization with biomoleculesDip coating for adsorption, covalent binding, self-assembled coating methods havebeen utilized for achievement of the smallest bioactive surface modification withDNA, peptides, and proteins. Dip coating is disadvantageous in terms of adsorbedbiomolecule replacement with components of body fluids. Hence, adsorption ofRGD peptide, collagen, or BMP by this technique did not show encouragingresults compared to conventional surfaces (Schliephake et al., 2009). To overcomethis complication, covalent binding of several chemicals/biomolecules has beensuggested (Cao et al., 2012; Kammerer et al., 2011; Poh et al., 2010; Shi et al.,2009; Lee et al., 2007; Secchi et al., 2007; Xiao et al., 1997). Although thetechnique still has shortcomings, such as the necessity for multistep and non-biocompatible component use, the use of polymeric brushes such as polyethyleneglycol-based linkers could increase the biomolecule stability and by thismodification, in vivo osseointegration could be enhanced (Park et al., 2011;352 CHAPTER 13 Tissue engineering applications and nanobiomaterials Germanier et al., 2006). Self-assembled coatings are peptide fibers that have beenmade functional by cell attachment proteins. Both nanostructure formation andbiomolecule integration can be achieved by this method. Osteoblast attachmentand differentiation have been enhanced by this method (Ceylan et al., 2014).Despite their in vitro success, nanofunctionalized surfaces should be tested withfurther in vivo and clinical trials evaluating long-term success of these systems.13.1.6.6 Nanotechnology for peri-implant mucosa attachmentBy modifying surgical procedures, macro- or microlevel designs of implants wereused to overcome soft tissue attachment problems. Recently, the use of nanotech-nology offered promising applications of this issue. A histological study comparingmucosal response of nanoroughened surface presented similar findings with othermaterials (Welander et al., 2008), but as mucosal cells are likely to respondoptimally to a different surface topography (Abrahamsson et al., 2002), the idealdental implant could exhibit separate areas with different bioactivity to bothencourage osseointegration and formation of more stable attachment apparatuswith the surrounding mucosa.13.1.6.7 Nanostructured surfaces in commercially available implantsIn various in vivo models testing nanolevel modifications on bone formation, BICand implant torque removal strength showed enhanced outcomes compared toconventional materials (Guo et al., 2007; Berglundh et al., 2007; Ben-Nissan andChoi, 2006; Mendes et al., 2007; Coelho and Suzuki, 2005; Park et al., 2005;Lickorish et al., 2007; Kubota et al., 2004; Jung et al., 2001; Meirelles et al.,2007; Chiesa et al., 2007). Today, only a few commercially available implantswith nanolevel modifications are present in the dental implant market. Beyondthese brands, several types are being prepa red to emerge after completing theirresearch and development process.13.1.6.7.1 Osseospeed (Astra Tech AB, Mo¨lndal, Sweden)This implant has a nanolevel rough surface generated by TiO2GB and HF AEmethods (Abron et al., 2001; Cooper et al., 2006). In addition to its microlevelroughness, nanolevel modifications at 50100 nm values can be observed inscanning electron microscope images. Compared to conventional microlevel roughsurfaces, osteoblastic cell differentiation markers and expression of IGF-2, BMP-2,and BMP-6 were increased in MSCs attached to this implant (Guo et al., 2007).Accelerated osseointegration, increased osseous formation, and related torqueremoval values were also indicated in in vivo experiments (Ellingsen et al., 2004;Berglundh et al., 2007; Abrahamsson et al., 2008; Dohan Ehrenfest et al., 2011;Jarmar et al., 2008; Kang et al., 2009; Choi et al., 2012).In clinical studies, successful results were reported with respect to enhancedremoval torque values (Kang et al., 2011) and patient-centered outcomes(Limmer et al., 2014; Raes et al., 2013). Moreover, Osseospeed implantsthat were placed immediately after tooth extraction (Cooper et al., 2014;35313.1 Nanobiomaterials and Implant Dentistry Cecchinato et al., 2015; Noelken et al., 2014; De Bruyn et al., 2013) or loadedimmediately after insertion (Oxby et al., 2014; Vervaeke et al., 2013; Collaertet al., 2011) also demonstrated satisfactory clinical outcomes in short- andlong-term clinical follow-ups. Although short ( Gulje et al., 2013; Gulje et al.,2012) and narrow (Galindo-Moreno et al., 2012) implants also showed successfultherapeutic outcomes, postloading complications, such as fixture fracture andscrew loosening, were also encountered (Cha et al., 2013).13.1.6.7.2 Nanotite (3i Implant Innovations, Palm Beach Gardens, FL)Nanolevel surface change was achieved by microlevel roughened titanium alloysurface wi th CP nanoparticle modification. A particulate solgel depositionmethod was utilized by using discrete crystalline deposition of CP to achieve50100 nm roughness.In a rat tibia model, approximately twofold bone formation and sixfoldtensile strength were detected with Nanotite implants compared to similar butmicroroughened surfaces (Mendes et al., 2007). BIC and osseointegration rate havealso been increased by these implants (Orsini et al., 2007; Goene et al., 2007).Clinical trials exhibited improved peri-impla nt hea ling afte r plac ement(Menicucci et a l., 2013; Marte ns et al., 2014), satisfactory aesthetics(Ostman et al., 2010a), and successful immediate loading results with regular(Cannizzaro et al., 2012; Ostman et al., 2010b; Cannizzaro et al., 2008)orshort-length (Felice et al., 2009) Nanotite implants.13.1.6.7.3 Ossean (Intra-Lock, FL, USA)Bioceramic blasting is made to structurally and chemically modify the surface ofthis implant (Marin et al., 2008). In experiments, although torque removal valuesof Ossean have been found to be higher than nanomodified Nanotite andOsseospeed implants, this outcome has also been associated with differentmacro- and microlevel topographies of the tested implants (Coelho and Suzuki,2005). Clinically, Ossean implants have been plac ed successfully with simulta-neous bone augmentation procedures (Simonpieri et al., 2011) and exhibitedaccelerated osseointegration (Shibli et al., 2010).13.1.6.7.4 BioHelix (Bra˚nemark Integration AB, Mo¨lndal, Sweden)This type of implant is partially nanomodified by laser ablation of pTi (Palmquistet al., 2012). In vivo, despite high values of removal torque having been detectedafter insertion of BioHelix implants, 50% of the implants have failed in the shortterm after placement (Palmquist et al., 2011). BioHelix nanomodified implantspresented successful short- and long-term clinical results (Thomsson and LarssonWexell, 2013; Thomsson and Esposito, 2008).354 CHAPTER 13 Tissue engineering applications and nanobiomaterials 13.2 NANOBIOMATERIALS IN PERIODONTOLOGYPeriodontal disease, trauma, tumor resections, or congenital abnormalities andatrophy after tooth loss are some of the common causes of soft and hard tissuedefects of the dentoalveolar complex. These defects cause loss of function,aesthetic problems, and impair patients’ quality of life. Re construction of tissuesin this area is often difficult to achieve due to the high complexity of the nativetissues and unique properties of the oral cavity (Ramseier et al., 2012).Autogenous, allogenic, xenogenic, and synt hetic biomat erial applications arecomponents of the surgical intervention; however, both alternatives have theirown shortcomings (Murugan and Ramakrishna, 2005).Autogenous tissues have been widely used and are still considered as the goldstandard as they contain all the main elements of tissue formation, namely cells,extracellular matrix, and growth factors (Pape et al., 2010). However, even themost advanced reconstructive techniques using autologous materials are ofteninsufficient to restore extensive or complex maxillofacial defects (Susarla et al.,2011). The use of autogenous tissue involves the need of harvest ing it froma donor site, with increases in costs, procedure time, patient discomfort, andpossible complications. Also, the volume of harvested tissues may not besufficient to fill or cover a defect, given the limited availability of autogenoustissues (Zouhary, 2010).Various exogenous substitute materials, including allografts, xenografts,and alloplasts, have been used in clinical practice over recent decades (Bauer andMuschler, 2000). These materials primarily act as scaffolds, supporting themigration of cells from the periphery of the grafted area. Unfortunately, whencomparing these biomaterials to autografts other limitations emerge. The presenceof cellular populations, orchestrating the release of growth factors, maintaining astable scaffold, and stimulating angiogenesis are key for successful tissue regener-ation as they play a fundamental role in the healing process (Taba et al., 2005).However, conventional biomaterials generally either have very low or no inherentbiological activit y and act mostly as gap-fillers, failing to restore tissue integrityand/or function (Izumi et al., 2011).Researchers seek new materials and methods to overcome the limitations anddifficulties of regenerative medicine. Research on nanotechnology and principlesof tissue engineering promise novel methods already translated to clinical practiceat some level.Nanotechnology is defined as the production and manipulation of materialson a scale of ,100 nm and integration of these nanoscopic materials into micro-scopic and macroscopic systems. Major advances in nanotechnology have alreadybeen serving in real-life applications like commercial products and medicine.Nanotechnology materials are composed of matter with a particle size smallerthan that of their conventional materials, but with the same basic atomic structure.There are two fundamental characteristics that distinguish one from the other.35513.2 Nanobiomaterials in Periodontology The behavior of nanophase materials is explained by quantum, rather than classical,mechanics. Particles with a grain size ,100 nm behave in a markedly differentway from larger particles in terms of physical, chemical, and biological properties.Also, as grain size decreases, surface area increases for a given volume (Sullivanet al., 2014). With the increase in the surface area, biomaterial interactions withhost fluids, cells, and tissues are enhanced (Mota-Filho et al., 2014).Tissue engineering principles translate the knowledge of developmentalbiology/wound healing and material science into novel clinical applications withthe involvement of three components: the signaling molecules, scaffold orsupporting matrices, and cells (Ivanovski et al., 2014). With expanding knowledgein cells/growth factor biology and much faster progress in material sciences,tissue-engineering applications are the future of regenerative dentistry andmedicine. Involvement of nanotechnology in tissue engineering is very promisingby manufacturing novel biomaterials with enhanced biological and physicalproperties.13.2.1 NANOTECHNOLOGY BIOM ATERIALS IN REGENERATIVEPERIODONTAL THERAPIESDifferent treatments have been suggested to regenerate the damaged periodontaltissues. Periodontal regeneration is defined as the regeneration of the tooth-supporting tissues including alveolar bone, periodontal ligament (PDL), and cemen-tum. The development of new cementum with PDL fibers connected to alveolarbone is the main goal of periodontal regeneration (Shue et al., 2012). In order toserve the goal of periodontal regeneration, applied biomaterial has to interact withdifferent cells involved at regeneration: PDL cells, cementoblasts, osteoblasts,and precursor cells residing in PDL and perivascular region. Current research,although not comprehensive, demonstrates that nanoparticle biomaterials may fulfillthe requirements of biomaterialhost cell/tissue interactions for realization ofperiodontal regeneration.13.2.1.1 Periodontal tissue engineering using nanostructure scaffoldsNanostructured scaffolds for bone and periodontal tissue engineering are apromising approach to overcome the obstacles for regeneration of the periodontaltissues. The use of cells may cover the problem of inadequacy of repopulation oftarget cells. The application of biological mediators will enhance the regenerativecapacities of both the residing and applied cells. Finally, the use of scaffold mayserve the attachment, biocompatibility, and vascularization goals (Akman et al.,2010; Chen and Jin, 2010). Various nanotechnology materials and their combina-tions have been tested for periodontal tissue engineering purposes. The clinical useof cell-based therapies is still in debate due to safety and ethical considerations.Almost all of the reports and research are limited to in vitro and animal studies.Some of the publications are summarized in Table 13.2.356 CHAPTER 13 Tissue engineering applications and nanobiomaterials These advantages and unique properties are not surprising considering humantissues such as bone and periodontium are also composed of nanostructuralcomponents: crystalline HA, type 1 collagen, noncollagenous proteins, and withspecial importance adhesion molecules (Tran and Webster, 2009; Murugan andRamakrishna, 2005). Cellular mechanotransduction relies on the ability ofproteins of the focal adhesion to change chemical activity state when physicallydistorted, converting mechanical energy into biochemical energy by modulatingthe kinetics of proteinprotein or proteinligand interactions within the cell(Biggs et al., 2010).13.2.1.2 Nanoparticle bone grafts: in vitro studies13.2.1.2.1 Osteoblasts and progenitorsAs bone formation is a common goal of various different regenerative medicinedisciplines including orthopedics, plastic surgery, neurosurgery, and oral surgery,enhancing regenerative capac ities of osteoblasts and their progenitors havebeen investigated extensively. One of the strategies is the use of nanoparticlebone grafts to enhance the regenerative capacity of these cells (Murugan andRamakrishna, 2005).Webster et al. (2000a) demonstrated the influence of nanoparticle ceramic onosteoblast adhesion in 1999. Compared to micron-sized particles, osteoblastadhesion was significantly higher on nanoparticle alumina and titanium substrates(,100 nm). Since an increase in osteoblast adhesion was observed for bothnanoparticles, osteoblast adhesion was enhanced by surface morphology and notby surface characteristics. Following research reporting enhanced osteoblastproliferation, ALP activity and mineralization by nanoparticle ceramic alsosupported these findings. The same research group investigated further theTable 13.2 Summary of Publications on Bone and Periodontal TissueEngineering Using Nanostructured ScaffoldsCellular Activity Cells Biomaterial ReferencesEnhancedadhesionOsteoprogenitor COsteoblastsPDL cellsPolystyrene-pBMAPolystyrene blendNano-HA-PCL-chitosanand nanobioactive glassBerry et al. (2006)Lim et al. (2005)Shalumon et al.(2013)IncreasedproliferationOsteoprogenitor COsteoblastsPDL cellsNano-HA-coated CPPolysisine-nano-HANano-HA-coated dermalmatrixHu et al. (2014)Pilloni et al. (2014)Ge et al. (2013)Matrix synthesisand mineralizationOsteoprogenitor COsteoblastsPDL cellsNSQ50 embossed PCLNanofibrous PCLSilicatitanateNano-HA-collagen-PLAKantawong et al.(2009)Baylan et al. (2013)Brie et al. (2014)He et al. (2010)35713.2 Nanobiomaterials in Periodontology mechanisms of induction osteoblast activity by nanophase ceramics. Increasedsurface area and change in surface characteristics enhanced vitronectin adhesionand related osteoblastic activities (Webster et al., 2000b).How nanoscale pits and grooves of biomaterials affect focal adhesion formationin osteoblasts and the osteoblastic differentiation of mesenchymal cells was investi-gated by evaluation of ERK/MAPK signaling pathway activation. The findingsrevealed that topographical modification can modulate cellular differentiation inmultipotent stem cells, regulated by the ERK/MAPK signaling pathway, known tobe activated by growth factors from TGF-β family and BMP-2, by enhancing cellu-lar adhesion (Biggs et al., 2009b). Biggs et al. (2009a) also evaluated the effectsof various modifications of nanosurfaces on cultured osteoblasts and STRO-1 1progenitor cells’ morphology, adhesion, and gene expressions. Random nanoislandsand nanocraters enhanced formation and maturation of adhesion mechanisms. Geneexpressions of growth factors related to osteoblastic differentiation like PDGF-BB,IGF-1, and TGF-β were also increased.13.2.1.2.2 PDL cellsThe major cell type in the PDL is the fibroblast. PDL cells are very important, asthey are the main cells to produce PDL fibers, a prerequisite of periodontalregeneration. These cells are quite different from gingival fibroblasts by means ofgene expressions and they have the capacity to differentiate into osteoblasts andcementoblasts. Also, undifferentiated MSCs reside in the PDL area, also shown tobe a very important cell niche for cellular events to regenerate periodontium(Chamila Prageeth Pandula et al., 2014; Chen and Jin, 2010). Although manypublications have investigated PDL cells cultured with nanostructured scaffold,research with currently available nanoparticle bone substitutes is limited.PDL cells cultured with nano-HA parti cles pres ented increased ALP activity,however, cell proliferation was similar in both groups. Nanoparticles were notedto be engulfed by PDL cells in dicating that nan osized particles are mo re absorb-able (Sun et al., 2007). Li et al. (2013) observed increased mitotic activity whenPDL cells were cul tured with nano-HA suspension via speeding up the cell cycle.PDL cells with nano-HA presented an earlier transition from G 1 into S phase(Li et al., 2013). Kasaj and colleagues investigated PDL cells stimulated withnano-HA paste (Ostim) comparing cell behavior with bovine serum albuminor enamel matrix protein derivative (Emdogain) stimulated PDL cells. The nano-HA gro up prese nted enhance d PDL proli feration and MAPK pathway activationcompared to the BSA group through activation of EGF activation (Kasaj et al.,2008b). Em dogain, known to be a favorable biologic mediator for periodontalregeneration, was found to be more potent at inducing the MAPK pathway.Kasaj et al . further inve stigated the efficacy of the nano-HA-coated surface.PDL mig ration was m ore efficiently mediated by EMD gradient as compa redwith the nano-HA. However, adhesion of PDLs to compound-coated dishes wasmore effectively mediated by nano-HA as comp ared with EMD. Also, c oatednano-HA stimulated PDL proliferation to a larger extent as compared with358 CHAPTER 13 Tissue engineering applications and nanobiomaterials coated EMD (Kasaj et al., 2012). PD L cells cultured with n ano-HA particlespres ented increased BMP-2 gene expression and MAPK pathway activationcomp ared to microsized particles (Suto et al., 2013).13.2.1.2.3 CementoblastsRoot cementum, a specialized mineralized tissue lining the tooth root surface,is another essential component of the periodontium and is a calcifi ed avascularmesenchymal tissue existing in acellular and cellular forms (Nanci and Bosshardt,2006). Cementum is anatomically attached to the tooth, but functi onally it is acomponent of the periodont ium, and is a substrate for attachment of principalPDL fibers, Sharpey’s fibers. Cementoblasts within the root of the tooth surfacebuild up the cementum (Grzesik and Narayanan, 2002).Limited in vitro research with cementoblasts is present since these cells aredifficult to isolate from their natural location. Data obtained using an immortal-ized cem entoblast cell line (OC-CM) demonstrates these cells have the potentialto be a valuable source for tissue engineering applications (Akman et al., 2010;Zhao et al., 2004). Research with cementoblasts cultured with nanopart iclebioactive glass demonstrated ionic products from the nanoparticles are shown toincrease cement oblast viability, mitochondrial activity, and cell proliferation(Carvalho et al., 2012).13.2.2 GUIDED TISSUE REGENERATION AND GUIDED BONEREGENERATION WITH NANOSTRUCTURED BARRIERMEMBRANES AND NANOPARTICLE BONE GRAFTS13.2.2.1 Guided tissue regeneration: guided bone regenerationGuided tissue regeneration (GTR) aims to regain lost periodontal tissues thatutilize the cell-occluding barrier between the gingival tissues and the periodontaldefect. With conventional periodontal surgery, periodontal defects are left emptyafter debridement. Epithelial cells and fibroblasts from the gingiva are the firstcells to repopulate at the defect region. As a result, fibroepithelial tissue is notformed with the original components of the periodontium (Chen and Jin, 2010).The use of a barrier membrane in GTR technique prevents epithelial downgrowthand gingival fibroblast migration to the defect. The maintenance of the spaceenables the repopulation of PDL cell cementoblasts and osteoblasts and theirprogenitors. Thus, instead of an attachment composed of a long epithelialattachment (healing by repair), periodontal regeneration can occur with the forma-tion of original attachment components (Wang and Cooke, 2005). Guided boneregeneration is a term used when barrier membranes are applied only to enhancebone regeneration at a defect site where no teeth are involved, therefore there is noexpectancy for the formation of new PDL or cementum. GBR techniques are usedfor vertical/horizontal augmentations, socket preservation, sinus augmentation,and peri-implantitis defects (Rakhmatia et al., 2013; Gentile et al., 2011).35913.2 Nanobiomaterials in Periodontology Various materials were used to fabricate barrier membranes for GTR/GBR andthese membranes are categorized as resorbable or nonresorbable. The biomaterialand physical properties of the membranes influence their function, and selection ofa specific material is based on the biological properties of the membrane as wellas the treatment requirements, with each material bearing inherent advantages anddisadvantages (Wang and Cooke, 2005; Rakhmatia et al., 2013).Resorbable materials that are used as membranes have either natural orsynthetic polymer structure natural or synthetic polymers. Collagen and syntheticpolymers, like polyglycolide or polylactide, are best known for their medicalapplicability (Hutmacher et al., 1996). Resorbable materials offer the advantage ofbeing resorbed by the body without the need of a second surgery to be removed.This property saves time and decreases the risk of the secondary surgery which isvery appealing both for the patient and the dentist (Chiapasco and Zaniboni,2009). The disadvantages of resorbable materials are their unpredictable degree ofdegradation, which may disrupt the wound-healing process and cause less boneformation. When the membranes are exposed the inflammatory reactions in theadjacent tissue, with the increased enzymatic activity of the local inflammatorycells, the membrane is degraded more rapidly. Another shortcoming is thatresorbable, especially collagen, membranes have low physical resistance and theygenerally lose strength, and collapse into the defect area (Wang and Cooke, 2005,Rakhmatia et al., 2013).Nonresorbable membranes, including polytetrafluoroethylene (PTFE) andtitanium mesh, have effective barrier function. With physical properties superiorto resorbable barriers, they can maintain the space beneath more efficiently.One drawback in the use of this type of membrane is the necessity for itsremoval with a second-stage surgical procedure (Nociti et al., 2001). Also,lower biocompatibility com pared to PLA or collagen membranes was reported(Takata et al., 2001).Synthetic barrier membranes with multilayers, sometimes in combination oforganic and inorganic layers have provided improved results maintaining bothgood biocompatibility and physical properties (Liao et al., 2007; Liao and Cui,2004). Two- or multilayer membranes can better fulfill the requirements of woundhealing by forming different environments for the side facing the defect or theside facing the gingiva. With composite and multilayer techniques openingnew insights for barrier membrane fabrication, nanotechnology provides furtheropportunities to improve efficiency. The use of appropriate nanostructures canimprove biocompatibi lity with enhanced cell adhesion, biomi metics, as well asphysical properties.Various nanostru ctured barrier membranes, including nanocarbonated HA-collagen-PLGA (Liao et al., 2008), nanofiber gelatin-HA (Kim et al., 2005a,b),polycaprolactone/calcium carbonate composite nanofibers (Fujihara et al., 2005),nanoapatite/PCL composite (Yang et al., 2009), silk fibroin nanofiber membranes(Kim et al., 2005a,b), nano-HA/poly(vinyl alcohol ) (n-HA/PVA) composite(Zeng et al., 2011), and nano-HA (n-HA)/poly(ε-caprolactone)-poly(ethylene360 CHAPTER 13 Tissue engineering applications and nanobiomaterials glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) (Fu et al., 2011) weretested in vitro and promising data were obtained. However, in vivo research onnanotechnology barrier membranes still remains limited.Nano-HA/polyamide-66 (nHA/PA66) membrane was tested in comparison toe-PTFE barrier in a rat study. nHA/PA66 membrane performed similar to ePTFEand was suggested as an alternative due to the absence of requirement for a secondsurgery (Zhang et al., 2010). The nHA/PA66 membranes were also implanted intosubcutaneous sites of nine SpragueDawley rats. The wounds and implant siteswere free from suppuration and necrosis in all periods. All nHA/PA66 membraneswere surrounded by fibrous capsule and it was concluded that nHA/PA66membrane showed excellent biocompatibility and indicated its use in GTR orGBR (Qu et al., 2010). A modification of the nHA/PA66, a membrane withantibacterial properties Ag-nHA-nTiO(2)/PA66 was fabricated. In vivo researchconcluded that these membranes are as biocompatible as nHA/PA66 membranes,thus they may be applied safely for GBR, providing better antibacterial activity atinfected sites (Ye et al., 2011).A composite barrier membrane with components, electrospun PLLA fiber,multiwalled nanocarbontubes, and nano-HA (PLLA-MWNCTs-HA) was fabri-cated. While the PLLA fibers formed a structure resembling native collagenfibers, nanocarbon tubes, and nano-HA particles increased biological activityand regulated degradation. In vitro studies proved PLLA-MWNCTs-HAmembrane degrades slowe r compared to PLLA and PLLA-HA mem brane s.Also, PDL cell proliferation was more enhanced in the PLLA-MWNCTs-HAgroup.PLLA-MWNCTs-HAmembraneswerealsotestedinanin vivo model.When implante d intr amusc ular ly and s eeded with PDL cell s, a fter 4 weeks ther ewas no evident inflammation at the i mplantat ion site. Newl y formed tissueshowed m ineralization, osteocalcin activity, and abundant new blood vessels(Cai and Yang, 2012).13.2.2.2 Nanoparticle bone grafts for GTR/GBRNanocrystalline-HA paste has been tested in animal models for the inductionof bone formation at experimental femoral, tibial, and craniofacial defects andbeneficial effects have been demonstrated (Huber et al., 2006; Brandt et al., 2010,Thorwarth et al., 2005). A case report on the use of nano-HA (Ostim) withradiographic biopsy findings after 3 years reveals that nanoparticles werewell-integrated with newly formed bone (Smeets et al., 2008). Case series offindings 6 months after surgery for the GBR treatment of peri-implantitis defectspresented that nanocrystalline-HA performed similar to bovine HA and collagenmembrane (Schwarz et al., 2006).The use of nanocrystalline calcium sulfate (Nanogen) for socket augmentationwas evaluated histologically and compared to medical-grade calcium sulfate in aclinical trial. Biopsies obtained at 1, 3, and 4 months after surgery revealed bothgroups showed similar healing socket fill. Nanogen-grafted sites presented betterhealing with less soft tissue formation at 4 months (Kumari et al., 2014).36113.2 Nanobiomaterials in Periodontology In a case series, nanostructured Mg-HA (SINTlife) was used in a combination ofnonresorbable barrier membrane for vertical ridge augmentation and simultaneousimplant placement. The authors reported 5.6 mm gain in bone height and survivalof all 42 rough surface implants after 3 months. Rapid increase in ISQ values,representing implant stability (49 at surgery and 63 after 3 months) enabledearly loading (Canullo and Sisti, 2010). Nanostructured Mg-HA was also testedin socket augmentation intervention in a randomized clinical trial, and bone speci-mens were collected 2 or 4 months after surgery. From the histomorphometricevaluation of the biopsies the author concluded that Mg-enriched HA is asuitable material for socket preservation and ensures early angiogenesis and earlyosteogenesis (Canullo et al., 2013).In a randomized clinical trial, application of nanocrystalline-HA paste wascompared to open flap debridement. Findings from 6 months of follow-up showedthat nanocrystalline-HA was more efficient at the pocket depth (PD) reduction andclinical attachment level (CAL) gain (Kasaj et al., 2008a). Nanocrystalline-HAwas used for the treatment of peri-implantitis defects in comparison to bovine-HA 1 collagen membrane. Nano-HA was found to be a suitable biomaterial,however the GBR group performed better when 4-year findings were evaluated(Schwarz et al., 2009). Similar findings were also reported from a human biopsystudy. PD reduction and CAL gain were obtained when nanocrystalline-HA wasused in the treatment of intrabony periodontal defects. However, biopsy findingsdemonstrated epithelial downgrowth and minimal new cement formation (Horvathet al., 2013). The findings suggest that increased biological activity of nano-HAwas not adequate at inhibiting epithelial downgrowth and should be used incombination with a barrier membrane.13.3 CONCLUSIONS AND FUTURE PERSPECTIVENanotechnology has the potential for enhancing bioactivity and osseointegrationat periodontal and dental implant therapy with its effects at cellular and molecularlevels. The scientific area that the materials are produced on 100 nm or less scaleand integrated into macro- or microlevel systems is defined as nanotechn ologyand has been already utilized in medicine and commercial product fabrication.With the recent developments, nanomodified products are now experimentallytested, some of which are also commercially available.There are several dental implant systems manufactured with various materialsand surface properties. Today, nanotechnology also has an emerging role inimplant dentistry in which it has effective functions in bone-related eventsand interactions that generate on various surfaces after implant placement. Bythes e interact ions, osseo integration process and associated clini cal succes s canbe improved. Although this hypothesis has been verified by several in vitro,in vivo, and clinical experiments, the substantial clinical contribution of “pop”362 CHAPTER 13 Tissue engineering applications and nanobiomaterials nanotechnology advances still remains controversial. Moreover, there is still alack of information invo lving long-term clinic al results and potential impact ofbone bonding behavior on the titanium surface and its underlying mechanismssuch as osteoinduction, osteoconduction, BIC, and osseointegration shouldbe revised at nanolevel. Therefore, long-term clinical follow-up trials should beconducted parallel with fundamental tests evaluating underlying mechanismsexplaining chemical techniqueostegenic activity interactions. In this way,development strategies can be ranged up and potential harms and risks aboutdeveloping nanotechnology in clinical health of dental implant candidates can behighlighted more.The soft tissue interface at the upper part (shoulder) of the implant is anothertopic that should be developed to advance into the ideal option(s) in im plantsurfacesurrounding epithelium/connective tissue connection. According to theliterature, potential contribution of nanotechnology to the interact ion at the softtissue interface remains unknown due to the low number of well-designed trialsexploring new nanotechnology applications for such an improvement.In the near future, nanotech nology has the potential to play one o f themost active roles in the creation of ideal implant surface and material proper-ties to obtain the best BIC with ideal soft tissue closure around. Moreover, byusing nanotechnology, dental implant success r ates can be enhanced with theaddition of molecules orienting the important cellular events and antibacterialactivities. These modifications will be modulated selectively in case of thespecific needs.Periodontal disease, trauma, resect ions, or atrophy are some common causesof dentoalveolar complex defects that need to be treated with a regenerativeapproach. Since alveolar bone and periodontal tissues have nanost ructure, a nano-composite structure to be more exact, the use of nanoparticle bone grafts seems tobe a plausible clinical approach in therapeutic approaches targeting periodontalregeneration. For this purpose, although numerous nanobiomaterials have beenfabricated and investigated, the research is predominantly at an in vitro level andonly a few types of nanoparticle bone grafts have been exhibited on the market.Although the use of these products for regenera tive therapies has also been testedin several clinical trials and some of the findings are promising, available dataeven for the commercially available products is still not adequate.GTR is a regenerative periodontal treatment that aims to regain lost tissues byplacing cell-occluding barriers between the gingival tissues and periodontal defectalone or in combination with bone grafts. Vascularization is one of the mostcritical prerequisites of periodontal regeneration. Nanotechnology was thought ofas a potential supporter of GTR by nanomodifications of these barrier membranes.Despite satisfactory in vitro results associated with these nanomodifiedmembranes/graft combinations, in vivo studies still remain to be enhanced byadvancing data before finding widespread use in clinical periodontal therapy.Moreover, very limi ted data are present on vascularization at the site treated bynanomodified GTR and grafts.36313.3 Conclusions and Future Perspective REFERENCESAbrahamsson, I., Albouy, J.P., Berglundh, T., 2008. Healing at fluoride-modified implantsplaced in wide marginal defects: an experimental study in dogs. Clin. Oral Implants Res.19, 153159. Available from:http://dx.doi.org/10.1111/j.1600-0501.2007.01454.x.Abrahamsson, I., Berglundh, T., Lindhe, J., 1998. Soft tissue response to plaque formationat different implant systems. A comparative study in the dog. Clin. Oral Implants Res.9, 7379.Abrahamsson, I., Zitzmann, N.U., Berglundh, T., Linder, E., Wennerberg, A., Lindhe, J.,2002. The mucosal attachment to titanium implants with different surface characteristics:an experimental study in dogs. J. Clin. Periodontol. 29, 448455.Abron, A., Hopfensperger, M., Thompson, J., Cooper, L.F., 2001. Evaluation of a predic-tive model for implant surface topography effects on early osseointegration in the rattibia model. J. Prosthet. Dent. 85, 40 46. Available from:http://dx.doi.org/10.1067/mpr.2001.112415.Adell, R., Eriksson, B., Lekholm, U., Branemark, P.I., Jemt, T., 1990. Long-term follow-up study of osseointegrated implants in the treatment of totally edentulous jaws. Int. J.Oral. Maxillofac. Implants 5, 347359.Adelow, C., Segura, T., Hubbell, J.A., Frey, P., 2008. The effect of enzymatically degrad-able polyethylene glycol. Hydrogels on smooth muscle cell phenotype. Biomaterials29, 314326. Available from:http://dx.doi.org/10.1016/j.biomaterials.2007.09.036.Advincula, M.C., Rahemtulla, F.G., Advincula, R.C., Ada, E.T., Lemons, J.E., Bellis, S.L.,2006. Osteoblast adhesion and matrix mineralization on sol-gel-derived titanium oxide.Biomaterials 27, 22012212. Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.11.014.Agis, H., Kandler, B., Fischer, M.B., Watzek, G., Gruber, R., 2009. Activated plateletsincrease fibrinolysis of mesenchymal progenitor cells. J. Orthop. Res. 27, 972980.Available from:http://dx.doi.org/10.1002/jor.20819.Akagawa, Y., Hosokawa, R., Sato, Y., Kamayama, K., 1998. Comparison between free-standing and tooth-connected partially stabilized zirconia implants after two years’function in monkeys: a clinical and histologic study. J. Prosthet. Dent. 80, 551558.Akman, A.C., Tigli, R.S., Gumusderelioglu, M., Nohutcu, R.M., 2010. bFGF-loaded HA-chitosan: a promising scaffold for periodontal tissue engineering. J. Biomed. Mater.Res. A 92, 953962. Available from:http://dx.doi.org/10.1002/jbm.a.32428.Al-Hamdan, K., Al-Moaber, S.H., Junker, R., Jansen, J.A., 2011. Effect of implant surfaceproperties on peri-implant bone healing: a histological and histomorphometric study indogs. Clin. Oral Implants Res. 22, 399405. Available from:http://dx.doi.org/10.1111/j.1600-0501.2010.02106.x.Andersson, A.S., Backhed, F., von Euler, A., Richter-Dahlfors, A., Sutherland, D.,Kasemo, B., 2003. Nanoscale features influence epithelial cell morphology and cyto-kine production. Biomaterials 24, 34273436.Aznavoorian, S., Stracke, M.L., Krutzsch, H., Schiffmann, E., Liotta, L.A., 1990. Signaltransduction for chemotaxis and haptotaxis by matrix molecules in tumor cells. J. Cell.Biol. 110, 14271438.Bagno, A., Di Bello, C., 2004. Surface treatments and roughness properties of Ti-basedbiomaterials. J. Mater. Sci. Mater. Med. 15, 935949. Available from:http://dx.doi.org/10.1023/B:JMSM.0000042679.28493.7f.364 CHAPTER 13 Tissue engineering applications and nanobiomaterials Baharloo, B., Textor, M., Brunette, D.M., 2005. Substratum roughness alters the growth,area, and focal adhesions of epithelial cells, and their proximity to titanium surfaces.J. Biomed. Mater. Res. A 74, 12 22. Available from:http://dx.doi.org/10.1002/jbm.a.30321.Balasundaram, G., Sato, M., Webster, T.J., 2006. Using hydroxyapatite nanoparticles anddecreased crystallinity to promote osteoblast adhesion similar to functionalizing withRGD. Biomaterials 27, 27982805. Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.12.008.Barrere, F., van der Valk, C.M., Meijer, G., Dalmeijer, R.A., de Groot, K., Layrolle, P.,2003. Osteointegration of biomimetic apatite coating applied onto dense and porousmetal implants in femurs of goats. J. Biomed. Mater. Res. B Appl. Biomater. 67,655665. Available from:http://dx.doi.org/10.1002/jbm.b.10057.Bauer, T.W., Muschler, G.F., 2000. Bone graft materials. An overview of the basic science.Clin. Orthop. Relat. Res., 1027.Baylan, N., Bhat, S., Ditto, M., Lawrence, J.G., Lecka-Czernik, B., Yildirim-Ayan, E.,2013. Polycaprolactone nanofiber interspersed collagen type-I scaffold for bone regen-eration: a unique injectable osteogenic scaffold. Biomed. Mater. 8, 045011. Availablefrom:http://dx.doi.org/10.1088/1748-6041/8/4/045011.Becker, W., Becker, B.E., Ricci, A., Bahat, O., Rosenberg, E., Rose, L.F., et al., 2000.A prospective multicenter clinical trial comparing one- and two-stage titanium screw-shaped fixtures with one-stage plasma-sprayed solid-screw fixtures. Clin. Implant Dent.Relat. Res. 2, 159165.Ben-Nissan, B., Choi, A.H., 2006. Sol-gel production of bioactive nanocoatings for medicalapplications. Part 1: an introduction. Nanomed. Lond. 1, 311319. Available from:http://dx.doi.org/10.2217/17435889.1.3.311.Bergers, G., Brekken, R., McMahon, G., Vu, T.H., Itoh, T., Tamaki, K., et al., 2000.Matrix metalloproteinase-9 triggers the angiogenic switch during carcinogenesis. Nat.Cell Biol. 2, 737744. Available from:http://dx.doi.org/10.1038/35036374.Berglundh, T., Abrahamsson, I., Albouy, J.P., Lindhe, J., 2007. Bone healing at implantswith a fluoride-modified surface: an experimental study in dogs. Clin. Oral ImplantsRes. 18, 147152. Available from:http://dx.doi.org/10.1111/j.1600-0501.2006.01309.x.Berglundh, T., Lindhe, J., 1996. Dimension of the periimplant mucosa. Biological widthrevisited. J. Clin. Periodontol. 23, 971973.Berglundh, T., Lindhe, J., Ericsson, I., Marinello, C.P., Liljenberg, B., Thomsen, P., 1991.The soft tissue barrier at implants and teeth. Clin. Oral Implants Res. 2, 8190.Berglundh, T., Lindhe, J., Jonsson, K., Ericsson, I., 1994. The topography of the vascularsystems in the periodontal and peri-implant tissues in the dog. J. Clin. Periodontol. 21,189193.Berry, C.C., Dalby, M.J., Oreffo, R.O., McCloy, D., Affrosman, S., 2006. The interactionof human bone marrow cells with nanotopographical features in three dimensionalconstructs. J. Biomed. Mater. Res. A 79, 431439. Available from:http://dx.doi.org/10.1002/jbm.a.30960.Bessho, K., Carnes, D.L., Cavin, R., Chen, H.Y., Ong, J.L., 1999. BMP stimulation ofbone response adjacent to titanium implants in vivo. Clin. Oral Implants Res. 10,212218.Biggs, M.J., Richards, R.G., Dalby, M.J., 2010. Nanotopographical modification: a regula-tor of cellular function through focal adhesions. Nanomedicine 6, 619633. Availablefrom:http://dx.doi.org/10.1016/j.nano.2010.01.009.365References Biggs, M.J., Richards, R.G., Gadegaard, N., McMurray, R.J., Affrossman, S., Wilkinson,C.D., et al., 2009a. Interactions with nanoscale topography: adhesion quantification andsignal transduction in cells of osteogenic and multipotent lineage. J. Biomed. Mater.Res. A 91, 195208. Available from:http://dx.doi.org/10.1002/jbm.a.32196.Biggs, M.J., Richards, R.G., Gadegaard, N., Wilkinson, C.D., Oreffo, R.O., Dalby, M.J.,2009b. The use of nanoscale topography to modulate the dynamics of adhesion forma-tion in primary osteoblasts and ERK/MAPK signalling in STRO-11 enriched skeletalstem cells. Biomaterials 30, 50945103. Available from:http://dx.doi.org/10.1016/j.biomaterials.2009.05.049.Bigi, A., Nicoli-Aldini, N., Bracci, B., Zavan, B., Boanini, E., Sbaiz, F., et al., 2007.In vitro culture of mesenchymal cells onto nanocrystalline hydroxyapatite-coatedTi13Nb13Zr alloy. J. Biomed. Mater. Res. A 82, 213221. Available from:http://dx.doi.org/10.1002/jbm.a.31132.Bitar, M., Friederici, V., Imgrund, P., Brose, C., Bruinink, A., 2012. In vitro bioactivity ofmicro metal injection moulded stainless steel with defined surface features. Eur. Cell.Mater. 23, 333347.Born, A.K., Rottmar, M., Lischer, S., Pleskova, M., Bruinink, A., Maniura-Weber, K.,2009. Correlating cell architecture with osteogenesis: first steps towards live single cellmonitoring. Eur. Cell. Mater. 18, 4960, 61 42; discussion 60.Boyne, P., Jones, S.D., 2004. Demonstration of the osseoinductive effect of bonemorphogenetic protein within endosseous dental implants. Implant Dent. 13, 180184.Brandt, J., Henning, S., Michler, G., Hein, W., Bernstein, A., Schulz, M., 2010.Nanocrystalline hydroxyapatite for bone repair: an animal study. J. Mater. Sci. Mater.Med. 21, 283294. Available from:http://dx.doi.org/10.1007/s10856-009-3859-1.Branemark, P.I., Adell, R., Albrektsson, T., Lekholm, U., Lundkvist, S., Rockler, B., 1983.Osseointegrated titanium fixtures in the treatment of edentulousness. Biomaterials 4,2528.Branemark, P.I., Adell, R., Breine, U., Hansson, B.O., Lindstrom, J., Ohlsson, A., 1969.Intra-osseous anchorage of dental prostheses. I. Experimental studies. Scand. J. Plast.Reconstr. Surg. 3, 81100.Branemark, P.I., Svensson, B., van Steenberghe, D., 1995. Ten-year survival rates of fixedprostheses on four or six implants ad modum Branemark in full edentulism. Clin. OralImplants Res. 6, 227231.Brie, I.C., Soritau, O., Dirzu, N., Berce, C., Vulpoi, A., Popa, C., et al., 2014. Comparativein vitro study regarding the biocompatibility of titanium-base composites infiltratedwith hydroxyapatite or silicatitanate. J. Biol. Eng. 8, 14. Available from:http://dx.doi.org/10.1186/1754-1611-8-14.Briggs, E.P., Walpole, A.R., Wilshaw, P.R., Karlsson, M., Palsgard, E., 2004. Formation ofhighly adherent nano-porous alumina on Ti-based substrates: a novel bone implantcoating. J. Mater. Sci. Mater. Med. 15, 10211029. Available from:http://dx.doi.org/10.1023/B:JMSM.0000042688.33507.12.Browne, M., Gregson, P.J., 2000. Effect of mechanical surface pretreatment on metal ionrelease. Biomaterials 21, 385392.Brunette, D.M., 1988. The effects of implant surface topography on the behavior of cells.Int. J. Oral Maxillofac. Implants 3, 231246.Buser, D., Broggini, N., Wieland, M., Schenk, R.K., Denzer, A.J., Cochran, D.L., et al.,2004. Enhanced bone apposition to a chemically modified SLA titanium surface.J. Dent. Res. 83, 529533.366 CHAPTER 13 Tissue engineering applications and nanobiomaterials Buser, D., Schenk, R.K., Steinemann, S., Fiorellini, J.P., Fox, C.H., Stich, H., 1991.Influence of surface characteristics on bone integration of titanium implants. A histo-morphometric study in miniature pigs. J. Biomed. Mater. Res. 25, 889902. Availablefrom:http://dx.doi.org/10.1002/jbm.820250708.Buser, D., Weber, H.P., Donath, K., Fiorellini, J.P., Paquette, D.W., Williams, R.C., 1992. Softtissue reactions to non-submerged unloaded titanium implants in beagle dogs.J. Periodontol. 63, 225235. Available from:http://dx.doi.org/10.1902/jop.1992.63.3.225.Cai, K., Bossert, J., Jandt, K.D., 2006. Does the nanometre scale topography of titaniuminfluence protein adsorption and cell proliferation? Colloids Surf. B Biointerfaces 49,136144. Available from:http://dx.doi.org/10.1016/j.colsurfb.2006.02.016.Cai, Q., Yang, X., 2012. Multiwalled carbon nanotubes, hydroxyapatite nanoparticlesincorporated GTR membranes. In: Ahmed, W., Subramani, K. (Eds.), EmergingNanotechnologies in Dentistry: Processes, Materials and Applications. Elsevier,London, pp. 151165.Cannizzaro, G., Felice, P., Leone, M., Ferri, V., Viola, P., Esposito, M., 2012. Immediateversus early loading of 6.5 mm-long flapless-placed single implants: a 4-year afterloading report of a split-mouth randomised controlled trial. Eur. J. Oral Implantol. 5,111121.Cannizzaro, G., Leone, M., Torchio, C., Viola, P., Esposito, M., 2008. Immediate versusearly loading of 7 mm-long flapless-placed single implants: a split-mouth randomisedcontrolled clinical trial. Eur. J. Oral Implantol. 1, 277292.Canullo, L., Sisti, A., 2010. Early implant loading after vertical ridge augmentation VRA.using e-PTFE titanium-reinforced membrane and nano-structured hydroxyapatite:2-year prospective study. Eur. J. Oral Implantol. 3, 5969.Canullo, L., Heinemann, F., Gedrange, T., Biffar, R., Kunert-Keil, C., 2013. Histologicalevaluation at different times after augmentation of extraction sites grafted with amagnesium-enriched hydroxyapatite: double-blinded randomized controlled trial. Clin.Oral Implants Res. 24, 398406. Available from:http://dx.doi.org/10.1111/clr.12035.Cao, X., Yu, W.Q., Qiu, J., Zhao, Y.F., Zhang, Y.L., Zhang, F.Q., 2012. RGD peptideimmobilized on TiO2nanotubes for increased bone marrow stromal cells adhesion andosteogenic gene expression. J. Mater. Sci. Mater. Med. 23, 527536. Available from:http://dx.doi.org/10.1007/s10856-011-4479-0.Carlsson, L.V., Alberktsson, T., Berman, C., 1989. Bone response to plasma-cleanedtitanium implants. Int. J. Oral Maxillofac. Implants 4, 199204.Carvalho, S.M., Oliveira, A.A., Jardim, C.A., Melo, C.B., Gomes, D.A., de Fatima Leite,M., et al., 2012. Characterization and induction of cementoblast cell proliferation bybioactive glass nanoparticles. J. Tissue Eng. Regen. Med. 6, 813821. Available from:http://dx.doi.org/10.1002/term.488.Catelas, I., Dwyer, J.F., Helgerson, S., 2008. Controlled release of bioactive transforminggrowth factor beta-1 from fibrin gels in vitro. Tissue Eng. C Methods 14, 119128.Available from:http://dx.doi.org/10.1089/ten.tec.2007.0262.Catelas, I., Sese, N., Wu, B.M., Dunn, J.C., Helgerson, S., Tawil, B., 2006. Human mesenchy-mal stem cell proliferation and osteogenic differentiation in fibrin gels in vitro. TissueEng. 12, 23852396. Available from:http://dx.doi.org/10.1089/ten.2006.12.2385.Cavalcanti-Adam, E.A., Volberg, T., Micoulet, A., Kessler, H., Geiger, B., Spatz, J.P.,2007. Cell spreading and focal adhesion dynamics are regulated by spacing of integrinligands. Biophys. J. 92, 29642974. Available from:http://dx.doi.org/10.1529/biophysj.106.089730.367References Cecchinato, D., Lops, D., Salvi, G.E., Sanz, M., 2015. A prospective, randomized, con-trolled study using OsseoSpeed implants placed in maxillary fresh extraction socket:soft tissues response. Clin. Oral Implants Res. 26, 2027. Available from:http://dx.doi.org/10.1111/clr.12295.Ceylan, H., Kocabey, S., Unal Gulsuner, H., Balcik, O.S., Guler, M.O., Tekinay, A.B.,2014. Bone-like mineral nucleating peptide nanofibers induce differentiation of humanmesenchymal stem cells into mature osteoblasts. Biomacromolecules 15, 24072418.Available from:http://dx.doi.org/10.1021/bm500248r.Cha, H.S., Kim, Y.S., Jeon, J.H., Lee, J.H., 2013. Cumulative survival rate and complica-tion rates of single-tooth implant; focused on the coronal fracture of fixture in theinternal connection implant. J. Oral Rehabil. 40, 595602. Available from:http://dx.doi.org/10.1111/joor.12065.Chamila Prageeth Pandula, P.K., Samaranayake, L.P., Jin, L.J., Zhang, C., 2014.Periodontal ligament stem cells: an update and perspectives. J. Investig. Clin. Dent. 5,8190. Available from:http://dx.doi.org/10.1111/jicd.12089.Chang, Y.L., Lew, D., Park, J.B., Keller, J.C., 1999. Biomechanical and morphometricanalysis of hydroxyapatite-coated implants with varying crystallinity. J. OralMaxillofac. Surg. 57, 10961108, discussion 11081099.Chavrier, C.A., Couble, M.L., 1999. Ultrastructural immunohistochemical study of intersti-tial collagenous components of the healthy human keratinized mucosa surroundingimplants. Int. J. Oral Maxillofac. Implants 14, 108112.Chen, F.M., Jin, Y., 2010. Periodontal tissue engineering and regeneration: currentapproaches and expanding opportunities. Tissue Eng. B Rev. 16, 219255. Availablefrom:http://dx.doi.org/10.1089/ten.TEB.2009.0562.Chiapasco, M., Zaniboni, M., 2009. Clinical outcomes of GBR procedures to correct peri-implant dehiscences and fenestrations: a systematic review. Clin. Oral Implants Res. 20(Suppl. 4), 113123. Available from:http://dx.doi.org/10.1111/j.1600-0501 .2009.0178 1.x.Chiesa, R., Giavaresi, G., Fini, M., Sandrini, E., Giordano, C., Bianchi, A., et al., 2007. Invitro and in vivo performance of a novel surface treatment to enhance osseointegrationof endosseous implants. Oral Surg. Oral. Med. Oral Pathol. Oral Radiol. Endod. 103,745756. Available from:http://dx.doi.org/10.1016/j.tripleo.2006.09.025.Chivu, M., Dima, S.O., Stancu, C.I., Dobrea, C., Uscatescu, V., Necula, L.G., et al., 2009.In vitro hepatic differentiation of human bone marrow mesenchymal stem cells underdifferential exposure to liver-specific factors. Transl. Res. 154, 122132. Availablefrom:http://dx.doi.org/10.1016/j.trsl.2009.05.007.Cho, S.A., Park, K.T., 2003. The removal torque of titanium screw inserted in rabbit tibiatreated by dual acid etching. Biomaterials 24, 36113617.Choi, J.Y., Lee, H.J., Jang, J.U., Yeo, I.S., 2012. Comparison between bioactive fluoridemodified and bioinert anodically oxidized implant surfaces in early bone responseusing rabbit tibia model. Implant Dent. 21, 124128. Available from:http://dx.doi.org/10.1097/ID.0b013e318249f283.Chun, A.L., Moralez, J.G., Webster, T.J., Fenniri, H., 2005. Helical rosette nanotubes: abiomimetic coating for orthopedics? Biomaterials 26, 73047309. Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.05.080.Cochran, D.L., Buser, D., ten Bruggenkate, C.M., Weingart, D., Taylor, T.M., Bernard,J.P., et al., 2002. The use of reduced healing times on ITI implants with a sandblastedand acid-etched SLA. Surface: early results from clinical trials on ITI SLA implants.Clin. Oral Implants Res. 13, 144153.368 CHAPTER 13 Tissue engineering applications and nanobiomaterials Cochran, D.L., Schenk, R.K., Lussi, A., Higginbottom, F.L., Buser, D., 1998. Boneresponse to unloaded and loaded titanium implants with a sandblasted and acid-etched surface : a histometric study in the canine mandible. J. Biomed. M ater. Res.40, 111.Coelho, P.G., Suzuki, M., 2005. Evaluation of an IBAD thin-film process as an alternativemethod for surface incorporation of bioceramics on dental implants: a study in dogs.J. Appl. Oral Sci. 13, 8792.Collaert, B., Wijnen, L., De Bruyn, H., 2011. A 2-year prospective study on immediate load-ing with fluoride-modified implants in the edentulous mandible. Clin. Oral Implants Res.22, 11111116. Available from:http://dx.doi.org/10.1111/j.1600-0501.2010.02077.x.Colon, G., Ward, B.C., Webster, T.J., 2006. Increased osteoblast and decreasedStaphylococcus epidermidis functions on nanophase ZnO and TiO2. J. Biomed. Mater.Res. A 78, 595604. Available from:http://dx.doi.org/10.1002/jbm.a.30789.Comut, A.A., Weber, H.P., Shortkroff, S., Cui, F.Z., Spector, M., 2001. Connective tissue ori-entation around dental implants in a canine model. Clin. Oral Implants Res. 12, 433440.Conner, K.A., Sabatini, R., Mealey, B.L., Takacs, V.J., Mills, M.P., Cochran, D.L., 2003.Guided bone regeneration around titanium plasma-sprayed, acid-etched, and hydroxy-apatite-coated implants in the canine model. J. Periodontol. 74, 658668.Cooper, L.F., Reside, G.J., Raes, F., Garriga, J.S., Tarrida, L.G., Wiltfang, J., et al., 2014.Immediate provisionalization of dental implants placed in healed alveolar ridges andextraction sockets: a 5-year prospective evaluation. Int. J. Oral Maxillofac. Implants29, 709717. Available from:http://dx.doi.org/10.11607/jomi.3617.Cooper, L.F., Zhou, Y., Takebe, J., Guo, J., Abron, A., Holmen, A., et al., 2006. Fluoridemodification effects on osteoblast behavior and bone formation at TiO2grit-blasted c.p.titanium endosseous implants. Biomaterials 27, 926936. Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.07.009.Daculsi, G., Laboux, O., Malard, O., Weiss, P., 2003. Current state of the art of biphasiccalcium phosphate bioceramics. J. Mater. Sci. Mater. Med. 14, 195200.Dalby, M.J., McCloy, D., Robertson, M., Wilkinson, C.D., Oreffo, R.O., 2006.Osteoprogenitor response to defined topographies with nanoscale depths. Biomaterials27, 13061315. Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.08.028.Davarpanah, M., Martinez, H., Tecucianu, J.F., Fromentin, O., Celletti, R., 2000. To conserveor implant: which choice of therapy? Int. J. Periodontics Restorative Dent. 20, 412422.Davies, J.E., 1998. Mechanisms of endosseous integration. Int. J. Prosthodont. 11, 391401.Davies, J.E., 2003. Understanding peri-implant endosseous healing. J. Dent. Educ. 67,932949.De Bruyn, H., Raes, F., Cooper, L.F., Reside, G., Garriga, J.S., Tarrida, L.G., et al., 2013.Three-years clinical outcome of immediate provisionalization of single Osseospeed.Implants in extraction sockets and healed ridges. Clin. Oral Implants Res. 24,217223. Available from:http://dx.doi.org/10.1111/j.1600-0501.2012.02449.x.de Groot, K., Wolke, J.G., Jansen, J.A., 1998. Calcium phosphate coatings for medicalimplants. Proc. Inst. Mech. Eng. H. 212, 137147.de Oliveira, P.T., Zalzal, S.F., Beloti, M.M., Rosa, A.L., Nanci, A., 2007. Enhancement ofin vitro osteogenesis on titanium by chemically produced nanotopography. J. Biomed.Mater. Res. A 80, 554564. Available from:http://dx.doi.org/10.1002/jbm.a.30955.Dean III, J.W., Culbertson, K.C., D’Angelo, A.M., 1995. Fibronectin and laminin enhancegingival cell attachment to dental implant surfaces in vitro. Int. J. Oral Maxillofac.Implants 10, 721728.369References Degidi, M., Artese, L., Scarano, A., Perrotti, V., Gehrke, P., Piattelli, A., 2006.Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascularendothelial growth factor expression, and proliferative activity in peri-implant softtissues around titanium and zirconium oxide healing caps. J. Periodontol. 77, 7380.Available from:http://dx.doi.org/10.1902/jop.2006.77.1.73.Deporter, D.A., Watson, P.A., Pilliar, R.M., Howley, T.P., Winslow, J., 1988. A histologicalevaluation of a functional endosseous, porous-surfaced, titanium alloy dental implantsystem in the dog. J. Dent. Res. 67, 11901195.Di Carmine, M., Toto, P., Feliciani, C., Scarano,A.,Tulli,A.,Strocchi,R.,etal.,2003. Spreading of epithelial cells on machined and sandblasted titanium surfaces:an in vitro study. J. Periodontol. 74, 289295. Available from:http://dx.doi.org/10.1902/jop.2003.74.3.289.Dohan Ehrenfest, D.M., Vazquez, L., Park, Y.J., Sammartino, G., Bernard, J.P., 2011.Identification card and codification of the chemical and morphological characteristicsof 14 dental implant surfaces. J. Oral Implantol. 37, 525542. Available from:http://dx.doi.org/10.1563/AAID-JOI-D-11-00080.Douglass, C.W., Shih, A., Ostry, L., 2002. Will there be a need for complete dentures inthe United States in 2020? J. Prosthet. Dent. 87, 58.Douglass, C.W., Watson, A.J., 2002. Future needs for fixed and removable partial denturesin the United States. J. Prosthet. Dent. 87, 914.Ehrbar, M., Rizzi, S.C., Hlushchuk, R., Djonov, V., Zisch, A.H., Hubbell, J.A., et al., 2007.Enzymatic formation of modular cell-instructive fibrin analogs for tissue engineering.Biomaterials 28, 38563866. Available from:http://dx.doi.org/10.1016/j.biomaterials.2007.03.027.Eisenbarth, E., Velten, D., Breme, J., 2007. Biomimetic implant coatings. Biomol. Eng. 24,2732. Available from:http://dx.doi.org/10.1016/j.bioeng.2006.05.016.El-Ghannam, A., Starr, L., Jones, J., 1998. Laminin-5 coating enhances epithelial cellattachment, spreading, and hemidesmosome assembly on Ti-6A1-4V implant materialin vitro. J. Biomed. Mater. Res. 41, 3040.Ellingsen, J.E., Johansson, C.B., Wennerberg, A., Holmen, A., 2004. Improved retentionand bone-tolmplant contact with fluoride-modified titanium implants. Int. J. OralMaxillofac. Implants 19, 659666.Engler, A.J., Sen, S., Sweeney, H.L., Discher, D.E., 2006. Matrix elasticity directs stemcell lineage specification. Cell 126, 677689. Available from:http://dx.doi.org/10.1016/j.cell.2006.06.044.Eppell, S.J., Tong, W., Katz, J.L., Kuhn, L., Glimcher, M.J., 2001. Shape and size ofisolated bone mineralites measured using atomic force microscopy. J. Orthop. Res. 19,10271034. Available from:http://dx.doi.org/10.1016/S0736-026601.00034-1.Ergun, C., Liu, H., Halloran, J.W., Webster, T.J., 2007. Increased osteoblast adhesion on nano-grained hydroxyapatite and tricalcium phosphate containing calcium titanate. J. Biomed.Mater. Res. A 80, 990997. Available from:http://dx.doi.org/10.1002/jbm.a.30923.Esposito, M., Ardebili, Y., Worthington, H.V., 2014. Interventions for replacing missingteeth: different types of dental implants. Cochrane Database Syst. Rev. 7, CD003815.doi:10.1002/14651858.CD003815.pub4.Felice, P., Cannizzaro, G., Checchi, V., Marchetti, C., Pellegrino, G., Censi, P., et al.,2009. Vertical bone augmentation versus 7 mm-long implants in posterior atrophicmandibles. Results of a randomised controlled clinical trial of up to 4 months afterloading. Eur. J. Oral Implantol. 2, 720.370 CHAPTER 13 Tissue engineering applications and nanobiomaterials Fiedler, J., Leucht, F., Waltenberger, J., Dehio, C., Brenner, R.E., 2005. VEGF-A and PlGF-1stimulate chemotactic migration of human mesenchymal progenitor cells. Biochem. Biophys.Res. Commun. 334, 561568. Available from:http://dx.doi.org/10.1016/j.bbrc.2005.06.116.Friedenstein, A.J., Petrakova, K.V., Kurolesova, A.I., Frolova, G.P., 1968. Heterotopic ofbone marrow. Analysis of precursor cells for osteogenic and hematopoietic tissues.Transplantation 6, 230247.Frosch, K.H., Barvencik, F., Viereck, V., Lohmann, C.H., Dresing, K., Breme, J., et al.,2004. Growth behavior, matrix production, and gene expression of human osteoblastsin defined cylindrical titanium channels. J. Biomed. Mater. Res. A 68, 325334.Available from:http://dx.doi.org/10.1002/jbm.a.20010.Fu, S.Z., Wang, X.H., Guo, G., Shi, S., Fan, M., Liang, H., et al., 2011. Preparation andproperties of nano-hydroxyapatite/PCL-PEG-PCL composite membranes for tissueengineering applications. J. Biomed. Mater. Res. B Appl Biomater. 97, 7483.Available from:http://dx.doi.org/10.1002/jbm.b.31788.Fujihara, K., Kotaki, M., Ramakrishna, S., 2005. Guided bone regeneration membranemade of polycaprolactone/calcium carbonate composite nano-fibers. Biomaterials 26,41394147. Available from:http://dx.doi.org/10.1016/j.biomaterials.2004.09.014.Galindo-Moreno, P., Nilsson, P., King, P., Becktor, J., Speroni, S., Schramm, A., et al.,2012. Clinical and radiographic evaluation of early loaded narrow diameter implants -1-year follow-up. Clin. Oral Implants Res. 23, 609616. Available from:http://dx.doi.org/10.1111/j.1600-0501.2011.02254.x.Ge, S., Zhao, N., Wang, L., Liu, H., Yang, P., 2013. Effects of hydroxyapatite nanostruc-ture on channel surface of porcine acellular dermal matrix scaffold on cell viability andosteogenic differentiation of human periodontal ligament stem cells. Int. J. Nanomed.8, 18871895. Available from:http://dx.doi.org/10.2147/IJN.S44695.Gentile, P., Chiono, V., Tonda-Turo, C., Ferreira, A.M., Ciardelli, G., 2011. Polymericmembranes for guided bone regeneration. Biotechnol. J. 6, 11871197. Availablefrom:http://dx.doi.org/10.1002/biot.201100294.Germanier, Y., Tosatti, S., Broggini, N., Textor, M., Buser, D., 2006. Enhanced bone appo-sition around biofunctionalized sandblasted and acid-etched titanium implant surfaces.A histomorphometric study in miniature pigs. Clin. Oral Implants Res. 17, 251257.Available from:http://dx.doi.org/10.1111/j.1600-0501.2005.01222.x.Geurs, N.C., Jeffcoat, R.L., McGlumphy, E.A., Reddy, M.S., Jeffcoat, M.K., 2002.Influence of implant geometry and surface characteristics on progressive osseointegra-tion. Int. J. Oral Maxillofac. Implants 17, 811815.Giannobile, W.V., Somerman, M.J., 2003. Growth and amelogenin-like factors in periodon-tal wound healing. A systematic review. Ann. Periodontol. 8, 193204. Availablefrom:http://dx.doi.org/10.1902/annals.2003.8.1.193.Giavaresi, G., Fini, M., Cigada, A., Chiesa, R., Rondelli, G., Rimondini, L., et al., 2003.Mechanical and histomorphometric evaluations of titanium implants with differentsurface treatments inserted in sheep cortical bone. Biomaterials 24, 15831594.Goene, R.J., Testori, T., Trisi, P., 2007. Influence of a nanometer-scale surface enhance-ment on de novo bone formation on titanium implants: a histomorphometric study inhuman maxillae. Int. J. Periodontics Restorative Dent. 27, 211219.Gotfredsen, K., Wennerberg, A., Johansson, C., Skovgaard, L.T., Hjorting-Hansen, E.,1995. Anchorage of TiO2-blasted, HA-coated, and machined implants: an experimentalstudy with rabbits. J. Biomed. Mater. Res. 29, 12231231. Available from:http://dx.doi.org/10.1002/jbm.820291009.371References Groessner-Schreiber, B., Neubert, A., Muller, W.D., Hopp, M., Griepentrog, M., Lange, K.P.,2003. Fibroblast growth on surface-modified dental implants: an in vitro study. J. Biomed.Mater. Res. A 64, 591599. Available from:http://dx.doi.org/10.1002/jbm.a.10417.Grzesik, W.J., Narayanan, A.S., 2002. Cementum and periodontal wound healing andregeneration. Crit. Rev. Oral Biol. Med. 13, 474484.Gulje, F., Abrahamsson, I., Chen, S., Stanford, C., Zadeh, H., Palmer, R., 2013. Implantsof 6 mm vs. 11 mm lengths in the posterior maxilla and mandible: a 1-year multicenterrandomized controlled trial. Clin. Oral Implants Res. 24, 13251331. Available from:http://dx.doi.org/10.1111/clr.12001.Gulje, F., Raghoebar, G.M., Ter Meulen, J.W., Vissink, A., Meijer, H.J., 2012. Mandibularoverdentures supported by 6 mm dental implants: a 1-year prospective cohort study.Clin. Implant Dent. Relat. Res. 14 (Suppl. 1), e59 e66. Available from:http://dx.doi.org/10.1111/j.1708-8208.2011.00358.x.Guo, J., Padilla, R.J., Ambrose, W., De Kok, I.J., Cooper, L.F., 2007. The effect of hydro-fluoric acid treatment of TiO2grit blasted titanium implants on adherent osteoblastgene expression in vitro and in vivo. Biomaterials 28, 54185425. Available from:http://dx.doi.org/10.1016/j.biomaterials.2007.08.032.Gutwein, L.G., Webster, T.J., 2004. Increased viable osteoblast density in the presence ofnanophase compared to conventional alumina and titania particles. Biomaterials 25,41754183. Available from:http://dx.doi.org/10.1016/j.biomaterials.2003.10.090.Guy, S.C., McQuade, M.J., Scheidt, M.J., McPherson 3rd, J.C., Rossmann, J.A., Van Dyke,T.E., 1993. In vitro attachment of human gingival fibroblasts to endosseous implantmaterials. J. Periodontol. 64, 542546. Available from:http://dx.doi.org/10.1902/jop.1993.64.6.542.Hamilton, D.W., Brunette, D.M., 2007. The effect of substratum topography on osteoblastadhesion mediated signal transduction and phosphorylation. Biomaterials 28,18061819. Available from:http://dx.doi.org/10.1016/j.biomaterials.2006.11.041.Hansen, J.C., Lim, J.Y., Xu, L.C., Siedlecki, C.A., Mauger, D.T., Donahue, H.J., 2007.Effect of surface nanoscale topography on elastic modulus of individual osteoblasticcells as determined by atomic force microscopy. J. Biomech. 40, 28652871.Available from:http://dx.doi.org/10.1016/j.jbiomech.2007.03.018.Hansson, S., 1999. The implant neck: smooth or provided with retention elements. A bio-mechanical approach. Clin. Oral Implants Res. 10, 394405.Hansson, S., 2000. Surface roughness parameters as predictors of anchorage strength inbone: a critical analysis. J. Biomech. 33, 12971303.Hansson, S., Norton, M., 1999. The relation between surface roughness and interfacialshear strength for bone-anchored implants. A mathematical model. J. Biomech. 32,829836.Hashimoto, M., Akagawa, Y., Nikai, H., Tsuru, H., 1989. Ultrastructure of the peri-implantjunctional epithelium on single-crystal sapphire endosseous dental implant loaded withfunctional stress. J. Oral Rehabil. 16, 261270.He, H., Yu, J., Cao, J., E, L., Wang, D., Zhang, H., et al., 2010. Biocompatibility andosteogenic capacity of periodontal ligament stem cells on nHAC/PLA and HA/TCPscaffolds. J. Biomater. Sci. Polym. Ed. Available from:http://dx.doi.org/10.1163/092050609X12587018007767.He, Q., Wan, C., Li, G., 2007. Concise review: multipotent mesenchymal stromal cellsin blood. Stem Cells 25, 6977. Available from:http://dx.doi.org/10.1634/stemcells.2006-0335.372 CHAPTER 13 Tissue engineering applications and nanobiomaterials Hobkirk, J.A., 1983. Progress in implant research. Int. Dent. J. 33, 341349.Hoogduijn, M.J., Crop, M.J., Peeters, A.M., Van Osch, G.J., Balk, A.H., Ijzermans, J.N.,et al., 2007. Human heart, spleen, and perirenal fat-derived mesenchymal stem cellshave immunomodulatory capacities. Stem Cells Dev. 16, 597604. Available from:http://dx.doi.org/10.1089/scd.2006.0110.Hormia, M., Kononen, M., 1994. Immunolocalization of fibronectin and vitronectinreceptors in human gingival fibroblasts spreading on titanium surfaces. J. Periodontal.Res. 29, 146152.Hormia, M., Kononen, M., Kivilahti, J., Virtanen, I., 1991. Immunolocalization of proteinsspecific for adhaerens junctions in human gingival epithelial cells grown on differentlyprocessed titanium surfaces. J. Periodontal. Res. 26, 491497.Horvath, A., Stavropoulos, A., Windisch, P., Lukacs, L., Gera, I., Sculean, A., 2013.Histological evaluation of human intrabony periodontal defects treated with an unsin-tered nanocrystalline hydroxyapatite paste. Clin. Oral Investig. 17, 423430. Availablefrom:http://dx.doi.org/10.1007/s00784-012-0739-8.Hu, J., Zhou, Y., Huang, L., Liu, J., Lu, H., 2014. Effect of nano-hydroxyapatite coatingon the osteoinductivity of porous biphasic calcium phosphate ceramics. BMCMusculoskelet. Disord. 15, 114. Available from:http://dx.doi.org/10.1186/1471-2474-15-114.Hu, Y., Cai, K., Luo, Z., Zhang, Y., Li, L., Lai, M., et al., 2012. Regulation of the differen-tiation of mesenchymal stem cells in vitro and osteogenesis in vivo by microenviron-mental modification of titanium alloy surfaces. Biomaterials 33, 35153528. Availablefrom:http://dx.doi.org/10.1016/j.biomaterials.2012.01.040.Huang, Y.C., Simmons, C., Kaigler, D., Rice, K.G., Mooney, D.J., 2005. Bone regenerationin a rat cranial defect with delivery of PEI-condensed plasmid DNA encoding for bonemorphogenetic protein-4 BMP-4. Gene Ther. 12, 418426. Available from:http://dx.doi.org/10.1038/sj.gt.3302439.Huber, F.X., McArthur, N., Hillmeier, J., Kock, H.J., Baier, M., Diwo, M., et al., 2006.Void filling of tibia compression fracture zones using a novel resorbable nanocrystal-line hydroxyapatite paste in combination with a hydroxyapatite ceramic core: firstclinical results. Arch. Orthop. Trauma Surg. 126, 533540. Available from:http://dx.doi.org/10.1007/s00402-006-0170-1.Hutmacher, D., Hurzeler, M.B., Schliephake, H., 1996. A review of material properties ofbiodegradable and bioresorbable polymers and devices for GTR and GBR applications.Int. J. Oral Maxillofac. Implants 11, 667678.Iacono, V.J., 2000. Dental implants in periodontal therapy. J. Periodontol. 71, 19341942.Available from:http://dx.doi.org/10.1902/jop.2000.71.12.1934.Isa, Z.M., Schneider, G.B., Zaharias, R., Seabold, D., Stanford, C.M., 2006. Effects offluoride-modified titanium surfaces on osteoblast proliferation and gene expression. Int.J. Oral Maxillofac. Implants 21, 203211.Ivanovski, S., Vaquette, C., Gronthos, S., Hutmacher, D.W., Bartold, P.M., 2014.Multiphasic scaffolds for periodontal tissue engineering. J. Dent. Res. 93, 12121221.Available from:http://dx.doi.org/10.1177/0022034514544301.Izumi, Y., Aoki, A., Yamada, Y., Kobayashi, H., Iwata, T., Akizuki, T., et al., 2011.Current and future periodontal tissue engineering. Periodontology 2000 56, 166187.Available from:http://dx.doi.org/10.1111/j.1600-0757.2010.00366.x.Jan Lindhe, T.B., Lang, N.P., 2008. Osseointegration. In: Lindhe, J. (Ed.), ClinicalPeriodontology and Implant Dentistry, fifth ed. Wiley-Blackwell, Oxford, pp. 99107.373References Jansen, J.A., de Wijn, J.R., Wolters-Lutgerhorst, J.M., van Mullem, P.J., 1985. Ultrastructuralstudy of epithelial cell attachment to implant materials. J. Dent. Res. 64, 891896.Jansen, J.A., van de Waerden, J.P., Wolke, J.G., de Groot, K., 1991. Histologic evaluation ofthe osseous adaptation to titanium and hydroxyapatite-coated titanium implants. J. Biomed.Mater. Res. 25, 973989. Available from:http://dx.doi.org/10.1002/jbm.820250805.Jarmar, T., Palmquist, A., Branemark, R., Hermansson, L., Engqvist, H., Thomsen, P.,2008. Characterization of the surface properties of commercially available dentalimplants using scanning electron microscopy, focused ion beam, and high-resolutiontransmission electron microscopy. Clin. Implant Dent. Relat. Res. 10, 1122.Available from:http://dx.doi.org/10.1111/j.1708-8208.2007.00056.x.Jeffcoat, M.K., McGlumphy, E.A., Reddy, M.S., Geurs, N.C., Proskin, H.M., 2003. A com-parison of hydroxyapatite (HA)-coated threaded, HA-coated cylindric, and titaniumthreaded endosseous dental implants. Int. J. Oral Maxillofac. Implants 18, 406410.Jian, H., Shen, X., Liu, I., Semenov, M., He, X., Wang, X.F., 2006. Smad3-dependentnuclear translocation of beta-catenin is required for TGF-beta1-induced proliferation ofbone marrow-derived adult human mesenchymal stem cells. Genes Dev. 20, 666674.Available from:http://dx.doi.org/10.1101/gad.1388806.Jo, Y.Y., Lee, H.J., Kook, S.Y., Choung, H.W., Park, J.Y., Chung, J.H., et al., 2007.Isolation and characterization of postnatal stem cells from human dental tissues. TissueEng. 13, 767773. Available from:http://dx.doi.org/10.1089/ten.2006.0192.Josse, S., Faucheux, C., Soueidan, A., Grimandi, G., Massiot, D., Alonso, B., et al., 2005.Novel biomaterials for bisphosphonate delivery. Biomaterials 26, 20732080.Available from:http://dx.doi.org/10.1016/j.biomaterials.2004.05.019.Jung, Y.C., Han, C.H., Lee, I.S., Kim, H.E., 2001. Effects of ion beam-assisted depositionof hydroxyapatite on the osseointegration of endosseous implants in rabbit tibiae. Int. J.Oral Maxillofac. Implants 16, 809818.Kammerer, P.W., Heller, M., Brieger, J., Klein, M.O., Al-Nawas, B., Gabriel, M., 2011.Immobilisation of linear and cyclic RGD-peptides on titanium surfaces and their impacton endothelial cell adhesion and proliferation. Eur. Cell. Mater. 21, 364372.Kang, B.S., Sul, Y.T., Oh, S.J., Lee, H.J., Albrektsson, T., 2009. XPS, AES and SEManalysis of recent dental implants. Acta Biomater. 5, 22222229. Available from:http://dx.doi.org/10.1016/j.actbio.2009.01.049.Kang, I.H., Kim, C.W., Lim, Y.J., Kim, M.J., 2011. A comparative study on the initial stabilityof different implants placed above the bone level using resonance frequency analysis. J.Adv. Prosthodont. 3, 190195. Available from:http://dx.doi.org/10.4047/jap.2011.3.4.19 0.Kantawong, F., Burgess, K.E., Jayawardena, K., Hart, A., Burchmore, R.J., Gadegaard, N.,et al., 2009. Whole proteome analysis of osteoprogenitor differentiation induced bydisordered nanotopography and mediated by ERK signalling. Biomaterials 30,47234731. Available from:http://dx.doi.org/10.1016/j.biomaterials.2009.05.040.Kasaj, A., Rohrig, B., Zafiropoulos, G.G., Willershausen, B., 2008a. Clinical evaluation ofnanocrystalline hydroxyapatite paste in the treatment of human periodontal bonydefects—a randomized controlled clinical trial: 6-month results. J. Periodontol. 79,394400. Available from:http://dx.doi.org/10.1902/jop.2008.070378.Kasaj, A., Willershausen, B., Junker, R., Stratul, S.I., Schmidt, M., 2012. Human periodon-tal ligament fibroblasts stimulated by nanocrystalline hydroxyapatite paste or enamelmatrix derivative. An in vitro assessment of PDL attachment, migration, and prolifera-tion. Clin. Oral Investig. 16, 745754. Available from:http://dx.doi.org/10.1007/s00784-011-0570-7.374 CHAPTER 13 Tissue engineering applications and nanobiomaterials Kasaj, A., Willershausen, B., Reichert, C., Rohrig, B., Smeets, R., Schmidt, M., 2008b.Ability of nanocrystalline hydroxyapatite paste to promote human periodontal ligamentcell proliferation. J. Oral Sci. 50, 279285.Kasten, F.H., Soileau, K., Meffert, R.M., 1990. Quantitative evaluation of human gingivalepithelial cell attachment to implant surfaces in vitro. Int. J. Periodontics RestorativeDent. 10, 6879.Ker, E.D., Nain, A.S., Weiss, L.E., Wang, J., Suhan, J., Amon, C.H., et al., 2011.Bioprinting of growth factors onto aligned sub-micron fibrous scaffolds for simulta-neous control of cell differentiation and alignment. Biomaterials 32, 80978107.Available from:http://dx.doi.org/10.1016/j.biomaterials.2011.07.025.Kim, H.-W., Song, J.-H., Kim, H.-E., 2005a. Nanofiber generation of gelatinhydroxyapatite biomimetics for guided tissue regeneration. Adv. Funct. Mater. 15,19881994.Kim, K.H., Jeong, L., Park, H.N., Shin, S.Y., Park, W.H., Lee, S.C., et al., 2005b. Biologicalefficacy of silk fibroin nanofiber membranes for guided bone regeneration. J. Biotechnol.120, 327339. Available from:http://dx.doi.org/10.1016/j.jbiotec.2005.06.033.Kohal, R.J., Weng, D., Bachle, M., Strub, J.R., 2004. Loaded custom-made zirconia andtitanium implants show similar osseointegration: an animal experiment. J. Periodontol.75, 12621268. Available from:http://dx.doi.org/10.1902/jop.2004.75.9.1262.Kokoti, M., Sivropoulou, A., Koidis, P., Garefis, P., 2001. Comparison of cell proliferationon modified dental ceramics. J. Oral Rehabil. 28, 880887.Kommireddy, D.S., Sriram, S.M., Lvov, Y.M., Mills, D.K., 2006. Stem cellattachment to layer-by-layer assembled TiO2nanoparticle thin films. Biomaterials27, 42964303. Available from:http://dx.doi.org/10.1016/j.biomaterials.2006.03.042.Kononen, M., Hormia, M., Kivilahti, J., Hautaniemi, J., Thesleff, I., 1992. Effect of surfaceprocessing on the attachment, orientation, and proliferation of human gingival fibro-blasts on titanium. J. Biomed. Mater. Res. 26, 13251341. Available from:http://dx.doi.org/10.1002/jbm.820261006.Kraehenbuehl, T.P., Zammaretti, P., Van der Vlies, A.J., Schoenmakers, R.G., Lutolf, M.P., Jaconi, M.E., et al., 2008. Three-dimensional extracellular matrix-directedcardioprogenitor differentiation: systematic modulation of a synthetic cell-responsivePEG-hydrogel. Biomaterials 29, 27572766. Available from:http://dx.doi.org/10.1016/j.biomaterials.2008.03.016.Kubota,S.,Johkura,K.,Asanuma,K.,Okouchi,Y.,Ogiwara,N.,Sasaki,K.,etal.,2004. Titanium oxide nanotubes for bone regeneration. J. Mater. Sci. Mater. Med.15, 10311035. Available from:http://dx.doi.org/10.1023/B:JMSM.0000042689.78768.77.Kumari, B., Gautam, D.K., Horowitz, R.A., Jain, A., Mahajan, A., 2014. An evaluation andcomparison of the efficacy of nanocrystalline calcium sulfate bone grafts (Nanogen)and medical-grade calcium sulfate bone grafts (Dentogen) in human extraction sockets.Compend. Contin. Educ. Dent. 35, e28e32.Kuznetsov, S.A., Friedenstein, A.J., Robey, P.G., 1997. Factors required for bone marrowstromal fibroblast colony formation in vitro. Br. J. Haematol. 97, 561570.Le Guehennec, L., Goyenvalle, E., Lopez-Heredia, M.A., Weiss, P., Amouriq, Y.,Layrolle, P., 2008. Histomorphometric analysis of the osseointegration of four differentimplant surfaces in the femoral epiphyses of rabbits. Clin. Oral Implants Res. 19,11031110. Available from:http://dx.doi.org/10.1111/j.1600-0501.2008.01547.x.375References Le Guehennec, L., Soueidan, A., Layrolle, P., Amouriq, Y., 2007. Surface treatments oftitanium dental implants for rapid osseointegration. Dent. Mater. 23, 844854.Available from:http://dx.doi.org/10.1016/j.dental.2006.06.025.Lee, H., Dellatore, S.M., Miller, W.M., Messersmith, P.B., 2007. Mussel-inspired surfacechemistry for multifunctional coatings. Science 318, 426430. Available from:http://dx.doi.org/10.1126/science.1147241.Lee, J.J., Rouhfar, L., Beirne, O.R., 2000. Survival of hydroxyapatite-coated implants: ameta-analytic review. J. Oral Maxillofac. Surg. 58, 13721379, discussion13791380.doi:10.1053/joms.2000.18269.Lepski, G., Jannes, C.E., Maciaczyk, J., Papazoglou, A., Mehlhorn, A.T., Kaiser, S., et al.,2010. Limited Ca21and PKA-pathway dependent neurogenic differentiation of humanadult mesenchymal stem cells as compared to fetal neuronal stem cells. Exp. Cell Res.316, 216231. Available from:http://dx.doi.org/10.1016/j.yexcr.2009.08.006.Li, F., Peng, J., Hu, R., Dong, X., Chen, W., Pan, Y., et al., 2013. Effect ofnano-hydroxyapatite suspension on cell proliferation and cycle in human periodontalligament cells. J. Nanosci. Nanotechnol. 13, 45604564.Liao, S.S., Cui, F.Z., 2004. In vitro and in vivo degradation of mineralized collagen-basedcomposite scaffold: nanohydroxyapatite/collagen/poly(L-lactide). Tissue Eng. 10,7380. Available from:http://dx.doi.org/10.1089/107632704322791718.Liao, S., Murugan, R., Chan, C.K., Ramakrishna, S., 2008. Processing nanoengineeredscaffolds through electrospinning and mineralization suitable for biomimetic bone tis-sue engineering. J. Mech. Behav. Biomed. Mater. 1, 252 260. Available from:http://dx.doi.org/10.1016/j.jmbbm.2008.01.007.Liao, S., Watari, F., Zhu, Y., Uo, M., Akasaka, T., Wang, W., et al., 2007. The degradationof the three layered nano-carbonated hydroxyapatite/collagen/PLGA composite mem-brane in vitro. Dent. Mater. 23, 11201128. Available from:http://dx.doi.org/10.1016/j.dental.2006.06.045.Lickorish, D., Guan, L., Davies, J.E., 2007. A three-phase, fully resorbable, polyester/calcium phosphate scaffold for bone tissue engineering: evolution of scaffold design.Biomaterials 28, 14951502. Available from:http://dx.doi.org/10.1016/j.biomaterials.2006.11.025.Lienemann, P.S., Lutolf, M.P., Ehrbar, M., 2012. Biomimetic hydrogels for controlled bio-molecule delivery to augment bone regeneration. Adv. Drug Deliv. Rev. 64,10781089. Available from:http://dx.doi.org/10.1016/j.addr.2012.03.010.Lim, J.Y., Donahue, H.J., 2007. Cell sensing and response to micro- and nanostructuredsurfaces produced by chemical and topographic patterning. Tissue Eng. 13,18791891. Available from:http://dx.doi.org/10.1089/ten.2006.0154.Lim, J.Y., Dreiss, A.D., Zhou, Z., Hansen, J.C., Siedlecki, C.A., Hengstebeck, R.W., et al.,2007. The regulation of integrin-mediated osteoblast focal adhesion and focal adhesionkinase expression by nanoscale topography. Biomaterials 28, 17871797. Availablefrom:http://dx.doi.org/10.1016/j.biomaterials.2006.12.020.Lim, J.Y., Hansen, J.C., Siedlecki, C.A., Runt, J., Donahue, H.J., 2005. Human foetalosteoblastic cell response to polymer-demixed nanotopographic interfaces. J. R. Soc.Interface 2, 97108. Available from:http://dx.doi.org/10.1098/rsif.2004.0019.Limmer, B., Sanders, A.E., Reside, G., Cooper, L.F., 2014. Complications and patient-centered outcomes with an implant-supported monolithic zirconia fixed dentalprosthesis: 1 year results. J. Prosthodont. 23, 267275. Available from:http://dx.doi.org/10.1111/jopr.12110.376 CHAPTER 13 Tissue engineering applications and nanobiomaterials Linder, L., Albrektsson, T., Branemark, P.I., Hansson, H.A., Ivarsson, B., Jonsson, U.,et al., 1983. Electron microscopic analysis of the bone-titanium interface. Acta Orthop.Scand. 54, 4552.Listgarten, M.A., Lai, C.H., 1975. Ultrastructure of the intact interface between anendosseous epoxy resin dental implant and the host tissues. J. Biol. Buccale 3, 1328.Liu, H., Slamovich, E.B., Webster, T.J., 2006. Increased osteoblast functions among nano-phase titania/polylactide-co-glycolide. composites of the highest nanometer surfaceroughness. J. Biomed. Mater. Res. A 78, 798807. Available from:http://dx.doi.org/10.1002/jbm.a.30734.Liu, Y., de Groot, K., Hunziker, E.B., 2005. BMP-2 liberated from biomimetic implantcoatings induces and sustains direct ossification in an ectopic rat model. Bone 36,745757. Available from:http://dx.doi.org/10.1016/j.bone.2005.02.005.Liu, Y., Yan, X., Sun, Z., Chen, B., Han, Q., Li, J., et al., 2007. Flk-11 adipose-derivedmesenchymal stem cells differentiate into skeletal muscle satellite cells and amelioratemuscular dystrophy in mdx mice. Stem Cells Dev. 16, 695706. Available from:http://dx.doi.org/10.1089/scd.2006.0118.Lutolf, M.P., Weber, F.E., Schmoekel, H.G., Schense, J.C., Kohler, T., Muller, R., et al., 2003.Repair of bone defects using synthetic mimetics of collagenous extracellular matrices.Nat. Biotechnol. 21, 513518. Available from:http://dx.doi.org/10.1038/nbt818.Mahoney, M.J., Anseth, K.S., 2006. Three-dimensional growth and function of neuraltissue in degradable polyethylene glycol hydrogels. Biomaterials 27, 22652274.Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.11.007.Marin, C., Granato, R., Suzuki, M., Gil, J.N., Piattelli, A., Coelho, P.G., 2008. Removaltorque and histomorphometric evaluation of bioceramic grit-blasted/acid-etched anddual acid-etched implant surfaces: an experimental study in dogs. J. Periodontol. 79,19421949. Available from:http://dx.doi.org/10.1902/jop.2008.080106.Marinucci, L., Balloni, S., Becchetti, E., Bistoni, G., Calvi, E.M., Lumare, E., et al., 2010.Effects of hydroxyapatite and Biostite on osteogenic induction of hMSC. Ann. Biomed.Eng. 38, 640648. Available from:http://dx.doi.org/10.1007/s10439-009-9898-4.Martens, F., Vandeweghe, S., Browaeys, H., De Bruyn, H., 2014. Peri-implant outcome ofimmediately loaded implants with a full-arch implant fixed denture: a 5-year prospec-tive case series. Int. J. Periodontics Restorative Dent. 34, 189197. Available from:http://dx.doi.org/10.11607/prd.1938.Martini, D., Fini, M., Franchi, M., Pasquale, V.D., Bacchelli, B., Gamberini, M., et al.,2003. Detachment of titanium and fluorohydroxyapatite particles in unloaded endoss-eous implants. Biomaterials 24, 13091316.McGlumphy, E.A., Peterson, L.J., Larsen, P.E., Jeffcoat, M.K., 2003. Prospective study of429 hydroxyapatite-coated cylindric omniloc implants placed in 121 patients. Int. J.Oral Maxillofac. Implants 18, 8292.McKinney Jr., R.V., Steflik, D.E., Koth, D.L., 1985. Evidence for a junctional epithelial attach-ment to ceramic dental implants. A transmission electron microscopic study. J. Periodontol.56, 579591. Available from:http://dx.doi.org/10.1902/jop.1985.56.10.5 79.McManus, A.J., Doremus, R.H., Siegel, R.W., Bizios, R., 2005. Evaluation of cytocompat-ibility and bending modulus of nanoceramic/polymer composites. J. Biomed. Mater.Res. A 72, 98106. Available from:http://dx.doi.org/10.1002/jbm.a.30204.Meirelles, L., Arvidsson, A., Albrektsson, T., Wennerberg, A., 2007. Increased boneformation to unstable nano rough titanium implants. Clin. Oral Implants Res. 18,326332. Available from:http://dx.doi.org/10.1111/j.1600-0501.2006.01308.x.377References Mendes, V.C., Moineddin, R., Davies, J.E., 2007. The effect of discrete calcium phosphatenanocrystals on bone-bonding to titanium surfaces. Biomaterials 28, 47484755.Available from:http://dx.doi.org/10.1016/j.biomaterials.2007.07.020.Menicucci, G., Mussano, F., Schierano, G., Rizzati, A., Aimetti, M., Gassino, G., et al.,2013. Healing properties of implants inserted concomitantly with anorganic bovinebone. A histomorphometric human study. Aust. Dent. J. 58, 5766. Available from:http://dx.doi.org/10.1111/adj.12032.Meraw, S.J., Reeve, C.M., 1999. Qualitative analysis of peripheralperi-implant bone and influence of alendronate sodium on early bone regeneration.J. Periodontol. 70, 12281233. Available from:http://dx.doi.org/10.1902/jop.1999.70.10.1228.Meraw, S.J., Reeve, C.M., Wollan, P.C., 1999. Use of alendronate in peri-implant defectregeneration. J. Periodontol. 70, 151158. Available from:http://dx.doi.org/10.1902/jop.1999.70.2.151.Meyle, J., Gultig, K., Wolburg, H., von Recum, A.F., 1993. Fibroblast anchorage tomicrotextured surfaces. J. Biomed. Mater. Res. 27, 15531557. Available from:http://dx.doi.org/10.1002/jbm.820271212.Miller, R., Guo, Z., Vogler, E.A., Siedlecki, C.A., 2006. Plasma coagulation response tosurfaces with nanoscale chemical heterogeneity. Biomaterials 27, 208215. Availablefrom:http://dx.doi.org/10.1016/j.biomaterials.2005.05.087.Mishima, Y., Lotz, M., 2008. Chemotaxis of human articular chondrocytes and mesenchy-mal stem cells. J. Orthop. Res. 26, 14071412. Available from:http://dx.doi.org/10.1002/jor.20668.Morganstein, D.L., Wu, P., Mane, M.R., Fisk, N.M., White, R., Parker, M.G., 2010.Human fetal mesenchymal stem cells differentiate into brown and white adipocytes: arole for ERRalpha in human UCP1 expression. Cell Res. 20, 434444. Available from:http://dx.doi.org/10.1038/cr.2010.11.Morris, H.F., Ochi, S., Spray, J.R., Olson, J.W., 2000. Periodontal-type measurementsassociated with hydroxyapatite-coated and non-HA-coated implants: uncovering to 36months. Ann. Periodontol. 5, 5667. Available from:http://dx.doi.org/10.1902/annals.2000.5.1.56.Mosesson, M.W., 2005. Fibrinogen and fibrin structure and functions. J. Thromb. Haemost.3, 18941904. Available from:http://dx.doi.org/10.1111/j.1538-7836.2005.01365.x.Mota-Filho, H.G., Soares, D.M., Ginani, F., Barboza, C.A.G., 2014. Cell adhesion in bonegrafts associated tonanotechnology: a systematic review. S. Braz. Dent. J. RSBO 11,7782.Murakami, Y., Maeda, M., 2005. DNA-responsive hydrogels that can shrink or swell.Biomacromolecules 6, 29272929. Available from:http://dx.doi.org/10.1021/bm0504330.Murugan, R., Ramakrishna, S., 2005. Development of nanocomposites for bone grafting.Comps. Sci. Technol. 65, 23852406.Murugan, R., Ramakrishna, S., 2007. Design strategies of tissue engineering scaffolds withcontrolled fiber orientation. Tissue Eng. 13, 18451866. Available from:http://dx.doi.org/10.1089/ten.2006.0078.Mustafa, K., Silva Lopez, B., Hultenby, K., Wennerberg, A., Arvidson, K., 1998.Attachment and proliferation of human oral fibroblasts to titanium surfaces blastedwith TiO2particles. A scanning electron microscopic and histomorphometric analysis.Clin. Oral Implants Res. 9, 195207.378 CHAPTER 13 Tissue engineering applications and nanobiomaterials Nanci, A., Bosshardt, D.D., 2006. Structure of periodontal tissues in health and disease.Periodontology 2000 40, 1128. Available from:http://dx.doi.org/10.1111/j.1600-0757.2005.00141.x.Nociti Jr., F.H., Machado, M.A., Stefani, C.M., Sallum, E.A., 2001. Absorbable versus nonab-sorbable membranes and bone grafts in the treatment of ligature-induced peri-implantitisdefects in dogs: a histometric investigation. Int. J. Oral Maxillofac. Implants 16, 646652.Noelken, R., Neffe, B.A., Kunkel, M., Wagner, W., 2014. Maintenance of marginal bonesupport and soft tissue esthetics at immediately provisionalized OsseoSpeed implantsplaced into extraction sites: 2-year results. Clin. Oral Implants Res. 25, 214220.Available from:http://dx.doi.org/10.1111/clr.12069.Novaes Jr., A.B., Papalexiou, V., Grisi, M.F., Souza, S.S., Taba Jr., M., Kajiwara, J.K.,2004. Influence of implant microstructure on the osseointegration of immediateimplants placed in periodontally infected sites. A histomorphometric study in dogs.Clin. Oral Implants Res. 15, 3443.Ogawa, T., Saruwatari, L., Takeuchi, K., Aita, H., Ohno, N., 2008. Ti nano-nodular struc-turing for bone integration and regeneration. J. Dent. Res. 87, 751756.Oh, S.H., Finones, R.R., Daraio, C., Chen, L.H., Jin, S., 2005. Growth of nano-scalehydroxyapatite using chemically treated titanium oxide nanotubes. Biomaterials 26,49384943. Available from:http://dx.doi.org/10.1016/j.biomaterials.2005.01.048.Oh, W., Kim, D.S., Yang, Y.S., Lee, J.K., 2008. Immunological properties of umbilicalcord blood-derived mesenchymal stromal cells. Cell. Immunol. 251, 116123.Available from:http://dx.doi.org/10.1016/j.cellimm.2008.04.003.Oliva, J., Oliva, X., Oliva, J.D., 2007. One-year follow-up of first consecutive 100 zirconiadental implants in humans: a comparison of 2 different rough surfaces. Int. J. OralMaxillofac. Implants 22, 430435.Ong, J.L., Carnes, D.L., Bessho, K., 2004. Evaluation of titanium plasma-sprayed andplasma-sprayed hydroxyapatite implants in vivo. Biomaterials 25, 46014606.Available from:http://dx.doi.org/10.1016/j.biomaterials.2003.11.053.Orsini, G., Piattelli, M., Scarano, A., Petrone, G., Kenealy, J., Piattelli, A., et al., 2007.Randomized, controlled histologic and histomorphometric evaluation of implants withnanometer-scale calcium phosphate added to the dual acid-etched surface in the humanposterior maxilla. J. Periodontol. 78, 209218. Available from:http://dx.doi.org/10.1902/jop.2007.060297.Oshida, Y., 2006. Bioscience and bioengineering of titanium materials. In: Oshida, Y. (Ed.),Bioscience and Bioengineering of Titanium Materials. Elsevier Science, London, p. 448.Ostman, P.O., Hupalo, M., del Castillo, R., Emery, R.W., Cocchetto, R., Vincenzi, G.,et al., 2010a. Immediate provisionalization of NanoTite implants in support of single-tooth and unilateral restorations: one-year interim report of a prospective, multicenterstudy. Clin. Implant Dent. Relat. Res. 12 (Suppl. 1), e47e55. Available from:http://dx.doi.org/10.1111/j.1708-8208.2009.00166.x.Ostman, P.O., Wennerberg, A., Albrektsson, T., 2010b. Immediate occlusal loading of NanoTitePREVAIL implants: a prospective 1-year clinical and radiographic study. Clin. Implant Dent.Relat. Res. 12, 3947. Available from:http://dx.doi.org/10.1111/j.1708-8208.2008.00128.x.Oxby, G., Oxby, F., Oxby, J., Saltvik, T., Nilsson, P., 2014. Early loading of fluoridatedimplants placed in fresh extraction sockets and healed bone: A 3- to 5-year clinical andradiographic follow-up study of 39 consecutive patients. Clin. Implant Dent. Relat.Res. Available from:http://dx.doi.org/10.1111/cid.12210.379References Ozaki, Y., Nishimura, M., Sekiya, K., Suehiro, F., Kanawa, M., Nikawa, H., et al., 2007.Comprehensive analysis of chemotactic factors for bone marrow mesenchymal stem cells.Stem Cells Dev. 16, 119129. Available from:http://dx.doi.org/10.1089/scd.2006.0032.Palmquist, A., Emanuelsson, L., Branemark, R., Thomsen, P., 2011. Biomechanical,histological and ultrastructural analyses of laser micro- and nano-structured titaniumimplant after 6 months in rabbit. J. Biomed. Mater. Res. B Appl. Biomater. 97,289298. Available from:http://dx.doi.org/10.1002/jbm.b.31814.Palmquist, A., Grandfield, K., Norlindh, B., Mattsson, T., Branemark, R., Thomsen, P.,2012. Bone-titanium oxide interface in humans revealed by transmission electronmicroscopy and electron tomography. J. R. Soc. Interface 9, 396400. Available from:http://dx.doi.org/10.1098/rsif.2011.0420.Papalexiou, V., Novaes Jr., A.B., Grisi, M.F., Souza, S.S., Taba Jr., M., Kajiwara, J.K.,2004. Influence of implant microstructure on the dynamics of bone healing aroundimmediate implants placed into periodontally infected sites. A confocal laser scanningmicroscopic study. Clin. Oral Implants Res. 15, 4453.Pape, H.C., Evans, A., Kobbe, P., 2010. Autologous bone graft: properties and techniques.J. Orthop. Trauma 24 (Suppl. 1), S36S40. Available from:http://dx.doi.org/10.1097/BOT.0b013e3181cec4a1.Park, J.C., Kim, H.M., Ko, J., 1998. Effects of extracellular matrix constituents on theattachment of human oral epithelial cells at the titanium surface. Int. J. OralMaxillofac. Implants 13, 826836.Park, J.W., Kurashima, K., Tustusmi, Y., An, C.H., Suh, J.Y., Doi, H., et al., 2011. Bonehealing of commercial oral implants with RGD immobilization through electrodepos-ited polyethylene glycol. In rabbit cancellous bone. Acta Biomater. 7, 32223229.Available from:http://dx.doi.org/10.1016/j.actbio.2011.04.015.Park, J.Y., Davies, J.E., 2000. Red blood cell and platelet interactions with titaniumimplant surfaces. Clin. Oral Implants Res. 11, 530539.Park, Y.S., Yi, K.Y., Lee, I.S., Han, C.H., Jung, Y.C., 2005. The effects of ion beam-assisted deposition of hydroxyapatite on the grit-blasted surface of endosseous implantsin rabbit tibiae. Int. J. Oral Maxillofac. Implants 20, 3138.Peled, E., Boss, J., Bejar, J., Zinman, C., Seliktar, D., 2007. A novel polyethylene glycol-fibrinogen hydrogel for tibial segmental defect repair in a rat model. J. Biomed. Mater.Res. A 80, 874884. Available from:http://dx.doi.org/10.1002/jbm.a.30928.Peter, B., Pioletti, D.P., Laib, S., Bujoli, B., Pilet, P., Janvier, P., et al., 2005. Calciumphosphate drug delivery system: influence of local zoledronate release on bone implantosteointegration. Bone 36, 5260. Available from:http://dx.doi.org/10.1016/j.bone.2004.10.004.Pilloni, A., Pompa, G., Saccucci, M., Di Carlo, G., Rimondini, L., Brama, M., et al., 2014.Analysis of human alveolar osteoblast behavior on a nano-hydroxyapatite substrate: anin vitro study. BMC Oral Health 14, 22. Available from:http://dx.doi.org/10.1186/1472-6831-14-22.Poh, C.K., Shi, Z., Lim, T.Y., Neoh, K.G., Wang, W., 2010. The effect of VEGF functio-nalization of titanium on endothelial cells in vitro. Biomaterials 31, 15781585.Available from:http://dx.doi.org/10.1016/j.biomaterials.2009.11.042.Popat, K.C., Chatvanichkul, K.I., Barnes, G.L., Latempa Jr., T.J., Grimes, C.A., Desai, T.A.,2007a. Osteogenic differentiation of marrow stromal cells cultured on nanoporousalumina surfaces. J. Biomed. Mater. Res. A 80, 955964. Available from:http://dx.doi.org/10.1002/jbm.a.31028.380 CHAPTER 13 Tissue engineering applications and nanobiomaterials Popat, K.C., Leoni, L., Grimes, C.A., Desai, T.A., 2007b. Influence of engineered titaniananotubular surfaces on bone cells. Biomaterials 28, 31883197. Available from:http://dx.doi.org/10.1016/j.biomaterials.2007.03.020.Price, R.L., Gutwein, L.G., Kaledin, L., Tepper, F., Webster, T.J., 2003. Osteoblastfunction on nanophase alumina materials: Influence of chemistry, phase, and topogra-phy. J. Biomed. Mater. Res. A 67, 12841293. Available from:http://dx.doi.org/10.1002/jbm.a.20011.Qu, Y., Wang, P., Man, Y., Li, Y., Zuo, Y., Li, J., 2010. Preliminary biocompatible evalua-tion of nano-hydroxyapatite/polyamide 66 composite porous membrane. Int. J.Nanomed. 5, 429 435.Raes, F., Cosyn, J., De Bruyn, H., 2013. Clinical, aesthetic, and patient-related outcome ofimmediately loaded single implants in the anterior maxilla: a prospective study inextraction sockets, healed ridges, and grafted sites. Clin. Implant Dent. Relat. Res. 15,819835. Available from:http://dx.doi.org/10.1111/j.1708-8208.2011.00438.x.Raisanen, L., Kononen, M., Juhanoja, J., Varpavaara, P., Hautaniemi, J., Kivilahti, J.,et al., 2000. Expression of cell adhesion complexes in epithelial cells seeded on bioma-terial surfaces. J. Biomed. Mater. Res. 49, 7987.Rakhmatia, Y.D., Ayukawa, Y., Furuhashi, A., Koyano, K., 2013. Current barriermembranes: titanium mesh and other membranes for guided bone regeneration indental applications. J. Prosthodont. Res. 57, 314. Available from:http://dx.doi.org/10.1016/j.jpor.2012.12.001.Ramseier, C.A., Rasperini, G., Batia, S., Giannobile, W.V., 2012. Advanced reconstructivetechnologies for periodontal tissue repair. Periodontology 2000 59, 185202. Availablefrom:http://dx.doi.org/10.1111/j.1600-0757.2011.00432.x.Reynolds, M.A., Aichelmann-Reidy, M.E., Branch-Mays, G.L., Gunsolley, J.C., 2003.The efficacy of bone replacement grafts in the treatment of periodontal osseous defects.A systematic review. Ann. Periodontol. 8, 227265. Available from:http://dx.doi.org/10.1902/annals.2003.8.1.227.Roccuzzo, M., Bunino, M., Prioglio, F., Bianchi, S.D., 2001. Early loading of sandblastedand acid-etched SLA. Implants: a prospective split-mouth comparative study. Clin.Oral Implants Res. 12, 572578.Rock, G., Neurath, D., Lu, M., Alharbi, A., Freedman, M., 2006. The contribution of plate-lets in the production of cryoprecipitates for use in a fibrin glue. Vox Sang. 91,252255. Available from:http://dx.doi.org/10.1111/j.1423-0410.2006.00788.x.Roos, J., Sennerby, L., Albrektsson, T., 1997. An update on the clinical documentation oncurrently used bone anchored endosseous oral implants. Dent. Update 24, 194200.Sauberlich, S., Klee, D., Richter, E.J., Hocker, H., Spiekermann, H., 1999. Cell culturetests for assessing the tolerance of soft tissue to variously modified titanium surfaces.Clin. Oral Implants Res. 10, 379393.Sawase, T., Jimbo, R., Baba, K., Shibata, Y., Ikeda, T., Atsuta, M., 2008. Photo-inducedhydrophilicity enhances initial cell behavior and early bone apposition. Clin. Oral ImplantsRes. 19, 491496. Available from:http://dx.doi.org/10.1111/j.1600-0501.2007.01509.x.Schliephake, H., Aref, A., Scharnweber, D., Bierbaum, S., Sewing, A., 2009. Effect ofmodifications of dual acid-etched implant surfaces on peri-implant bone formation.Part I: organic coatings. Clin. Oral Implants Res. 20, 3137. Available from:http://dx.doi.org/10.1111/j.1600-0501.2008.01603.x.Schroeder, A., Buser, D.A., 1989. ITI-system. Basic and clinical procedures. Shigaku 77,12671288.381References Schroeder, A., van der Zypen, E., Stich, H., Sutter, F., 1981. The reactions of bone,connective tissue, and epithelium to endosteal implants with titanium-sprayed surfaces.J. Maxillofac. Surg. 9, 1525.Schwarz, F., Bieling, K., Latz, T., Nuesry, E., Becker, J., 2006. Healing of intrabonyperi-implantitis defects following application of a nanocrystalline hydroxyapatiteOstim. or a bovine-derived xenograft Bio-Oss. In combination with a collagenmembrane Bio-Gide. A case series. J. Clin. Periodontol. 33, 491499. Available from:http://dx.doi.org/10.1111/j.1600-051X.2006.00936.x.Schwarz, F., Ferrari, D., Herten, M., Mihatovic, I., Wieland, M., Sager, M., et al., 2007a.Effects of surface hydrophilicity and microtopography on early stages of soft and hardtissue integration at non-submerged titanium implants: an immunohistochemical studyin dogs. J. Periodontol. 78, 21712184. Available from:http://dx.doi.org/10.1902/jop.2007.070157.Schwarz, F., Herten, M., Sager, M., Wieland, M., Dard, M., Becker, J., 2007b. Histologicaland immunohistochemical analysis of initial and early osseous integration at chemicallymodified and conventional SLA titanium implants: preliminary results of a pilot studyin dogs. Clin. Oral Implants Res. 18, 481488. Available from:http://dx.doi.org/10.1111/j.1600-0501.2007.01341.x.Schwarz, F., Sahm, N., Bieling, K., Becker, J., 2009. Surgical regenerative treatment ofperi-implantitis lesions using a nanocrystalline hydroxyapatite or a natural bone mineralin combination with a collagen membrane: a four-year clinical follow-up report.J. Clin. Periodontol. 36, 807814. Available from:http://dx.doi.org/10.1111/j.1600-051X.2009.01443.x.Scotchford, C.A., Gilmore, C.P., Cooper, E., Leggett, G.J., Downes, S., 2002. Proteinadsorption and human osteoblast-like cell attachment and growth on alkylthiol on goldself-assembled monolayers. J. Biomed. Mater. Res. 59, 8499.Secchi, A.G., Grigoriou, V., Shapiro, I.M., Cavalcanti-Adam, E.A., Composto, R.J.,Ducheyne, P., et al., 2007. RGDS peptides immobilized on titanium alloy stimulatebone cell attachment, differentiation and confer resistance to apoptosis. J. Biomed.Mater. Res. A 83, 577584. Available from:http://dx.doi.org/10.1002/jbm.a.31007.Shalumon, K.T., Sowmya, S., Sathish, D., Chennazhi, K.P., Nair, S.V., Jayakumar, R.,2013. Effect of incorporation of nanoscale bioactive glass and hydroxyapatite in PCL/chitosan nanofibers for bone and periodontal tissue engineering. J. Biomed.Nanotechnol. 9, 430440.Shen, W., Zhang, K., Kornfield, J.A., Tirrell, D.A., 2006. Tuning the erosion rate of artifi-cial protein hydrogels through control of network topology. Nat. Mater. 5, 153158.Available from:http://dx.doi.org/10.1038/nmat1573.Sher, P., Custodio, C.A., Mano, J.F., 2010. Layer-by-layer technique for producingporous nanostructured 3D constructs using moldable freeform assembly of sphericaltemplates. Small 6, 26442648. Available from:http://dx.doi.org/10.1002/smll.201001066.Shi, Z., Neoh, K.G., Kang, E.T., Poh, C., Wang, W., 2009. Titanium with surface-grafteddextran and immobilized bone morphogenetic protein-2 for inhibition of bacterialadhesion and enhancement of osteoblast functions. Tissue Eng. A 15, 417426.Available from:http://dx.doi.org/10.1089/ten.tea.2007.0415.Shibli, J.A., Grassi, S., Piattelli, A., Pecora, G.E., Ferrari, D.S., Onuma, T., et al., 2010.Histomorphometric evaluation of bioceramic molecular impregnated and dual acid-etched implant surfaces in the human posterior maxilla. Clin. Implant Dent. Relat. Res.12, 281288. Available from:http://dx.doi.org/10.1111/j.1708-8208.2009.00174.x.382 CHAPTER 13 Tissue engineering applications and nanobiomaterials Shue, L., Yufeng, Z., Mony, U., 2012. Biomaterials for periodontal regeneration: a reviewof ceramics and polymers. Biomatter 2, 271277. Available from:http://dx.doi.org/10.4161/biom.22948.Simion, M., Baldoni, M., Rossi, P., 1991. A study on the attachment of human gingivalcell structures to oral implant materials. Int. J. Prosthodont. 4, 543547.Simonpieri, A., Choukroun, J., Del Corso, M., Sammartino, G., Dohan Ehrenfest, D.M.,2011. Simultaneous sinus-lift and implantation using microthreaded implants and leu-kocyte- and platelet-rich fibrin as sole grafting material: a six-year experience. ImplantDent. 20, 2 12. Available from:http://dx.doi.org/10.1097/ID.0b013e3181faa8af.Smeets, R., Grosjean, M.B., Jelitte, G., Heiland, M., Kasaj, A., Riediger, D., et al., 2008.[Hydroxyapatite bone substitute Ostim. In sinus floor elevation. Maxillary sinus flooraugmentation: bone regeneration by means of a nanocrystalline in-phase hydroxyapatiteOstim.]. Schweiz Monatsschr Zahnmed 118, 203212.Stanford, C.M., 1999. Biomechanical and functional behavior of implants. Adv. Dent. Res.13, 8892.Stanford, C.M., Brand, R.A., 1999. Toward an understanding of implant occlusion andstrain adaptive bone modeling and remodeling. J. Prosthet. Dent. 81, 553561.Stenport, V.F., Roos-Jansaker, A.M., Renvert, S., Kuboki, Y., Irwin, C., Albrektsson, T.,et al., 2003. Failure to induce supracrestal bone growth between and around partiallyinserted titanium implants using bone morphogenetic protein BMP: an experimentalstudy in dogs. Clin. Oral Implants Res. 14, 219225.Streicher, R.M., Schmidt, M., Fiorito, S., 2007. Nanosurfaces and nanostructures forartificial orthopedic implants. Nanomed. Lond. 2, 861874. Available from:http://dx.doi.org/10.2217/17435889.2.6.861.Sullivan, M.P., McHale, K.J., Parvizi, J., Mehta, S., 2014. Nanotechnology: current con-cepts in orthopaedic surgery and future directions. Bone Joint J. 96-B, 569573.Available from:http://dx.doi.org/10.1302/0301-620X.96B5.33606.Sun, W., Chu, C., Wang, J., Zhao, H., 2007. Comparison of periodontal ligament cellsresponses to dense and nanophase hydroxyapatite. J. Mater. Sci. Mater. Med. 18,677683. Available from:http://dx.doi.org/10.1007/s10856-006-0019-8.Susarla, S.M., Swanson, E., Gordon, C.R., 2011. Craniomaxillofacial reconstruction usingallotransplantation and tissue engineering: challenges, opportunities, and potentialsynergy. Ann. Plast. Surg. 67, 655661. Available from:http://dx.doi.org/10.1097/SAP.0b013e31822c00e6.Suto, M., Nemoto, E., Kanaya, S., Suzuki, R., Tsuchiya, M., Shimauchi, H., 2013.Nanohydroxyapatite increases BMP-2 expression via a p38 MAP kinase dependentpathway in periodontal ligament cells. Arch. Oral Biol. 58, 10211028. Availablefrom:http://dx.doi.org/10.1016/j.archoralbio.2013.02.014.Swope, E.M., James, R.A., 1981. A longitudinal study on hemidesmosome formation at thedental implant-tissue overflow. J. Oral Implantol. 9, 412422.Taba Jr., M., Jin, Q., Sugai, J.V., Giannobile, W.V., 2005. Current concepts in periodontalbioengineering. Orthod. Craniofac. Res. 8, 292302. Available from:http://dx.doi.org/10.1111/j.1601-6343.2005.00352.x.Taba Jr., M., Novaes Jr., A.B., Souza, S.L., Grisi, M.F., Palioto, D.B., Pardini, L.C., 2003.Radiographic evaluation of dental implants with different surface treatments: anexperimental study in dogs. Implant Dent. 12, 252258.Takata, T., Wang, H.L., Miyauchi, M., 2001. Attachment, proliferation and differentiationof periodontal ligament cells on various guided tissue regeneration membranes.J. Periodontal. Res. 36, 322327.383References Tamura, R.N., Oda, D., Quaranta, V., Plopper, G., Lambert, R., Glaser, S., et al., 1997.Coating of titanium alloy with soluble laminin-5 promotes cell attachment andhemidesmosome assembly in gingival epithelial cells: potential application to dentalimplants. J. Periodontal. Res. 32, 287294.Tatakis, D.N., Koh, A., Jin, L., Wozney, J.M., Rohrer, M.D., Wikesjo, U.M., 2002. Peri-implant bone regeneration using recombinant human bone morphogenetic protein-2 ina canine model: a dose-response study. J. Periodontal. Res. 37, 93100.Tavares, M.G., de Oliveira, P.T., Nanci, A., Hawthorne, A.C., Rosa, A.L., Xavier, S.P.,2007. Treatment of a commercial, machined surface titanium implant with H2SO4/H2O2enhances contact osteogenesis. Clin. Oral Implants Res. 18, 452458. Availablefrom:http://dx.doi.org/10.1111/j.1600-0501.2007.01344.x.Testori, T., Wiseman, L., Woolfe, S., Porter, S.S., 2001. A prospective multicenter clinicalstudy of the Osseotite implant: four-year interim report. Int. J. Oral Maxillofac.Implants 16, 193200.Thomsson, M., Esposito, M., 2008. A retrospective case series evaluating BranemarkBioHelix implants placed in a specialist private practice following “conventional”procedures. One-year results after placement. Eur. J. Oral Implantol. 1, 229234.Thomsson, M., Larsson Wexell, C., 2013. A 5-year retrospective case series evaluatingBranemark Integration BioHelix. Dental implants placed in a private practice by a spe-cialist. Acta Odontol. Scand. 71, 11951199. Available from:http://dx.doi.org/10.3109/00016357.2012.757362.Thorwarth, M., Schultze-Mosgau, S., Kessler, P., Wiltfang, J., Schlegel, K.A., 2005. Boneregeneration in osseous defects using a resorbable nanoparticular hydroxyapatite.J. Oral Maxillofac. Surg. 63, 16261633. Available from:http://dx.doi.org/10.1016/j.joms.2005.06.010.Tinsley, D., Watson, C.J., Russell, J.L., 2001. A comparison of hydroxylapatite coatedimplant retained fixed and removable mandibular prostheses over 4 to 6 years. Clin.Oral Implants Res. 12, 159166.Tran, N., Webster, T.J., 2009. Nanotechnology for bone materials. Wiley Interdiscip. Rev.Nanomed. Nanobiotechnol. 1, 336351. Available from:http://dx.doi.org/10.1002/wnan.23.Trisi, P., Lazzara, R., Rao, W., Rebaudi, A., 2002. Bone-implant contact and bone quality:evaluation of expected and actual bone contact on machined and osseotite implantsurfaces. Int. J. Periodontics Restorative Dent. 22, 535545.Trisi, P., Marcato, C., Todisco, M., 2003. Bone-to-implant apposition with machined andMTX microtextured implant surfaces in human sinus grafts. Int. J. PeriodonticsRestorative Dent. 23, 427437.Tzaphlidou, M., 2005. The role of collagen in bone structure: an image processingapproach. Micron 36, 593601. Available from:http://dx.doi.org/10.1016/j.micron.2005.05.009.Urban, R.M., Jacobs, J.J., Tomlinson, M.J., Gavrilovic, J., Black, J., Peoc’h, M., 2000.Dissemination of wear particles to the liver, spleen, and abdominal lymph nodes ofpatients with hip or knee replacement. J. Bone Joint Surg. Am. 82, 457476.Vasita, R., Katti, D.S., 2006. Nanofibers and their applications in tissue engineering. Int. J.Nanomed. 1, 1530.Vervaeke, S., Collaert, B., De Bruyn, H., 2013. The effect of implant surface modificationson survival and bone loss of immediately loaded implants in the edentulous mandible.Int. J. Oral Maxillofac. Implants 28, 13521357. Available from:http://dx.doi.org/10.11607/jomi.3200.384 CHAPTER 13 Tissue engineering applications and nanobiomaterials Vetter, U., Eanes, E.D., Kopp, J.B., Termine, J.D., Robey, P.G., 1991. Changes in apatitecrystal size in bones of patients with osteogenesis imperfecta. Calcif. Tissue Int. 49,248250.Vogel, J.P., Szalay, K., Geiger, F., Kramer, M., Richter, W., Kasten, P., 2006. Platelet-richplasma improves expansion of human mesenchymal stem cells and retains differentia-tion capacity and in vivo bone formation in calcium phosphate ceramics. Platelets 17,462469. Available from:http://dx.doi.org/10.1080/09537100600758867.Walles, T., Lichtenberg, A., Puschmann, C., Leyh, R., Wilhelmi, M., Kallenbach, K., et al.,2003. In vivo model for cross-species porcine endogenous retrovirus transmission usingtissue engineered pulmonary arteries. Eur. J. Cardiothorac. Surg. 24, 358363.Wan, Y., Wang, Y., Liu, Z., Qu, X., Han, B., Bei, J., et al., 2005. Adhesion and prolifera-tion of OCT-1 osteoblast-like cells on micro- and nano-scale topography structuredpoly(L-lactide). Biomaterials 26, 44534459. Available from:http://dx.doi.org/10.1016/j.biomaterials.2004.11.016.Wang, H.L., Cooke, J., 2005. Periodontal regeneration techniques for treatment ofperiodontal diseases. Dent. Clin. North Am. 49, 637659, vii.doi:10.1016/j.cden.2005.03.004.Webster, T.J., Ejiofor, J.U., 2004. Increased osteoblast adhesion on nanophase metals: Ti,Ti6Al4V, and CoCrMo. Biomaterials 25, 47314739. Available from:http://dx.doi.org/10.1016/j.biomaterials.2003.12.002.Webster, T.J., Ergun, C., Doremus, R.H., Siegel, R.W., Bizios, R., 2000a. Enhancedfunctions of osteoblasts on nanophase ceramics. Biomaterials 21, 18031810.Webster, T.J., Ergun, C., Doremus, R.H., Siegel, R.W., Bizios, R., 2000b. Specific proteinsmediate enhanced osteoblast adhesion on nanophase ceramics. J. Biomed. Mater. Res.51, 475483.Webster, T.J., Ergun, C., Doremus, R.H., Lanford, W.A., 2003. Increased osteoblastadhesion on titanium-coated hydroxyapatite that forms CaTiO3. J. Biomed. Mater. Res.A 67, 975 980. Available from:http://dx.doi.org/10.1002/jbm.a.10160.Webster, T.J., Hellenmeyer, E.L., Price, R.L., 2005. Increased osteoblast functions on theta 1delta nanofiber alumina. Biomaterials 26, 953960. Available from:http://dx.doi.org/10.1016/j.biomaterials.2004.03.040.Webster, T.J., Schadler, L.S., Siegel, R.W., Bizios, R., 2001. Mechanisms of enhancedosteoblast adhesion on nanophase alumina involve vitronectin. Tissue Eng. 7,291301. Available from:http://dx.doi.org/10.1089/10763270152044152.Webster, T.J., Siegel, R.W., Bizios, R., 1999. Osteoblast adhesion on nanophase ceramics.Biomaterials 20, 12211227.Webster, T.J., Smith, T.A., 2005. Increased osteoblast function on PLGA compositescontaining nanophase titania. J. Biomed. Mater. Res. A 74, 677686. Available from:http://dx.doi.org/10.1002/jbm.a.30358.Weibrich, G., Hansen, T., Kleis, W., Buch, R., Hitzler, W.E., 2004. Effect of plateletconcentration in platelet-rich plasma on peri-implant bone regeneration. Bone 34,665671. Available from:http://dx.doi.org/10.1016/j.bone.2003.12.010.Welander, M., Abrahamsson, I., Berglundh, T., 2008. The mucosal barrier at implant abut-ments of different materials. Clin. Oral Implants Res. 19, 635641. Available from:http://dx.doi.org/10.1111/j.1600-0501.2008.01543.x.Wennerberg, A., Albrektsson, T., 2000. Suggested guidelines for the topographicevaluation of implant surfaces. Int. J. Oral Maxillofac. Implants 15, 331344.385References Wennerberg, A., Albrektsson, T., Andersson, B., Krol, J.J., 1995. A histomorphometric andremoval torque study of screw-shaped titanium implants with three different surfacetopographies. Clin. Oral Implants Res. 6, 2430.Wennerberg, A., Bolind, P., Albrektsson, T., 1991. Glow-discharge pretreated implantscombined with temporary bone tissue ischemia. Swed. Dent. J. 15, 95101.Wennerberg, A., Ektessabi, A., Albrektsson, T., Johansson, C., Andersson, B., 1997.A 1-year follow-up of implants of differing surface roughness placed in rabbit bone.Int. J. Oral Maxillofac. Implants 12, 486494.Wennerberg, A., Hallgren, C., Johansson, C., Danelli, S., 1998. A histomorphometric eval-uation of screw-shaped implants each prepared with two surface roughnesses. Clin.Oral Implants Res. 9, 1119.Wheeler, S.L., 1996. Eight-year clinical retrospective study of titanium plasma-sprayed andhydroxyapatite-coated cylinder implants. Int. J. Oral Maxillofac. Implants 11, 340350.Wickham, M.Q., Erickson, G.R., Gimble, J.M., Vail, T.P., Guilak, F., 2003. Multipotentstromal cells derived from the infrapatellar fat pad of the knee. Clin. Orthop. Relat.Res., 196212. Available from:http://dx.doi.org/10.1097/01.blo.0000072467.53786.ca.Wikesjo, U.M., Sorensen, R.G., Kinoshita, A., Wozney, J.M., 2002. RhBMP-2/alphaBSMinduces significant vertical alveolar ridge augmentation and dental implant osseointe-gration. Clin. Implant Dent. Relat. Res. 4, 174182.Wong, C., Inman, E., Spaethe, R., Helgerson, S., 2003. Fibrin-based biomaterials to deliverhuman growth factors. Thromb. Haemost. 89, 573582. Available from:http://dx.doi.org/10.1267/THRO03030573.Wong, M., Eulenberger, J., Schenk, R., Hunziker, E., 1995. Effect of surface topology onthe osseointegration of implant materials in trabecular bone. J. Biomed. Mater. Res. 29,15671575. Available from:http://dx.doi.org/10.1002/jbm.820291213.Xiao, S.J., Textor, M., Spencer, N.D., Wieland, M., Keller, B., Sigrist, H., 1997.Immobilization of the cell-adhesive peptide Arg-Gly-Asp-Cys RGDC. On titaniumsurfaces by covalent chemical attachment. J. Mater. Sci. Mater. Med. 8, 867872.Yang, F., Both, S.K., Yang, X., Walboomers, X.F., Jansen, J.A., 2009. Development of anelectrospun nano-apatite/PCL composite membrane for GTR/GBR application. ActaBiomater. 5, 32953304. Available from:http://dx.doi.org/10.1016/j.actbio.2009.05.023.Ye, J., Yao, Q., Mo, A., Nie, J., Liu, W., Ye, C., et al., 2011. Effects of an antibacterialmembrane on osteoblast-like cells in vitro. Int. J. Nanomed. 6, 18531861. Availablefrom:http://dx.doi.org/10.2147/IJN.S17749.Yokoyama, K., Ichikawa, T., Murakami, H., Miyamoto, Y., Asaoka, K., 2002. Fracturemechanisms of retrieved titanium screw thread in dental implant. Biomaterials 23,24592465.Zannettino, A.C., Paton, S., Arthur, A., Khor, F., Itescu, S., Gimble, J.M., et al., 2008.Multipotential human adipose-derived stromal stem cells exhibit a perivascular pheno-type in vitro and in vivo. J. Cell. Physiol. 214, 413421. Available from:http://dx.doi.org/10.1002/jcp.21210.Zeng, S., Fu, S., Guo, G., Liang, H., Qian, Z., Tang, X., et al., 2011. Preparation andcharacterization of nano-hydroxyapatite/polyvinyl alcohol. Composite membranes forguided bone regeneration. J. Biomed. Nanotechnol. 7, 549557.Zhang, J., Huang, C., Xu, Q., Mo, A., Li, J., Zuo, Y., 2010. Biological properties of abiomimetic membrane for guided tissue regeneration: a study in rat calvarial defects.Clin. Oral Implants Res. 21, 392397. Available from:http://dx.doi.org/10.1111/j.1600-0501.2009.01857.x.386 CHAPTER 13 Tissue engineering applications and nanobiomaterials Zhao, G., Raines, A.L., Wieland, M., Schwartz, Z., Boyan, B.D., 2007. Requirement forboth micron- and submicron scale structure for synergistic responses of osteoblasts tosubstrate surface energy and topography. Biomaterials 28, 28212829. Available from:http://dx.doi.org/10.1016/j.biomaterials.2007.02.024.Zhao, G., Schwartz, Z., Wieland, M., Rupp, F., Geis-Gerstorfer, J., Cochran, D.L., et al.,2005. High surface energy enhances cell response to titanium substrate microstructure.J. Biomed. Mater. Res. A 74, 4958. Available from:http://dx.doi.org/10.1002/jbm.a.30320.Zhao, G., Zinger, O., Schwartz, Z., Wieland, M., Landolt, D., Boyan, B.D., 2006. Osteoblast-like cells are sensitive to submicron-scale surface structure. Clin. Oral Implants Res. 17,258264. Available from:http://dx.doi.org/10.1111/j.1600-0501.2005.01195.x.Zhao, M., Jin, Q., Berry, J.E., Nociti Jr., F.H., Giannobile, W.V., Somerman, M.J., 2004.Cementoblast delivery for periodontal tissue engineering. J. Periodontol. 75, 154161.Available from:http://dx.doi.org/10.1902/jop.2004.75.1.154.Zink, C., Hall, H., Brunette, D.M., Spencer, N.D., 2012. Orthogonal nanometer-micrometerroughness gradients probe morphological influences on cell behavior. Biomaterials 33,80558061. Available from:http://dx.doi.org/10.1016/j.biomaterials.2012.07.037.Zouhary, K.J., 2010. Bone graft harvesting from distant sites: concepts and techniques.Oral Maxillofac. Surg. Clin. North Am. 22, 301316, v. Available from:http://dx.doi.org/10.1016/j.coms.2010.04.007.387References

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