14 Nanobiomaterials in endodontics










CHAPTER
14
Nanobiomaterials
in endodontics
Maryam Khoroushi
1
, Abbas Ali Khademi
2
, M az iar Ebrahimi Dastgurdi
3
and
Majid Abdolrahi mi
4
1
Dental Materials Research Center and Department of Operative Dentistry, School of Dentistry,
Isfahan University of Medical Sciences, Isfahan, Iran
2
Torabinejad Dental Research Center and
Department of Endodontics, School of Dentistry, Isfahan University of Medical Sciences,
Isfahan, Iran
3
Maxillofacial Stem Cells Research Center and Department of Endodontics,
School of Dentistry, Islamic Azad University, Isfahan (Khorasgan Branch), Isfahan, Iran
4
School of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran
14.1 INTRODUCTION
Since World War II, when Dr Orban described pulpal pathosis, endodontic
treatments have progressively become more popular among and accepted by
patients and dentists. Root canal therapy (RCT) as the most commonly per-
formed treatment in endodontics is based on mechanical and chemical clean-
ing a nd shaping of the canal and filling the canal with inert materials. O ver
the past decades, improvements in techniques, instruments, and materials h ave
dramatically increased the success rate of RCTs.
On the other hand, regenerative concepts have opened new horizons to
endodontic treatments. In regenerative procedures the main goal is not to
remove the pulp and fill the canal but to retain the pulp tissue and provoke the
repair mechanism o f the pulp (such as direct pulp c appin g or ape xoge nesis
procedure) or to provoke the existing stem cells to produce new vital pulp
tissue in the canal (such as the revascularization procedure).
Nano-sizing improves the bioavailability and bioactivity of the materials. In
endodontics, r esearchers have studied using these nanosized materials in differ-
ent areas of endodontics. Nanoparticles in irrigat ion solutions and obturating
materials, in osteoconductive a nd osteoinductive materials, in drug-delivery
systems and in scaffolds are some of the possible applications of nanomaterials
in endodontics.
In this chapter we will review some of the recent developments in nano-
materials used in endodontics.
389
Nanobiomaterials in Dentistry. DOI: http://dx.doi.org/10.1016/B978-0-323-42867-5.00014-X
© 2016 Elsevier Inc. All rights reserved.

14.2 NANOPARTICLES AS IRRIGANTS
AND ANTIMICROBIAL AGENTS
Disinfection of the root canal system plays a key role in the success of root canal
treatment. Various irrigants and medicaments with different antibacterial activities
and physical properties have been used in endodontics. Despite outstanding proper-
ties of many of these irrigants and medicaments, none of them has all the ideal
characteristics of an antibacterial agent. Therefore, efforts have focused on improv-
ing the properties of the existing irrigants and medicaments and one of the ways to
achieve this goal is reducing the particle size of these agents to the nano-scale.
The higher surface area and charge density of nanoparticles enable them to more
efficiently interact with bacterial cells and give them more antibacterial potential
compared to antibacterial powders (
Kishen et al., 2008; Yamamoto, 2001). They
have broad-spectrum antibacterial activity and lower potential for provoking bacterial
resistance (Kishen, 2010
). Silver, zinc oxide, chitosan, bioactive glass, and calcium
hydroxide are some materials with high antibacterial activity as nanoparticles.
14.2.1 CALCIUM HYDROXIDE
For many years calcium hydroxide nanoparticles (CH NPs) have been investigated
in different fields of science (
Roy and Bhattacharya, 2010; Salvadori and Dei,
2001) but studies on CH NPs are limited in dentistry. Comparison of cytotoxicity
of CH and CH NPs on fibroblast cell lines showed that CH and CH NPs have
comparable cytotoxic effects at 24, 48, and 72 h. Both types of CH had a signifi-
cantly lower toxicity at 72 h compared to 24 and 48 h (Dianat et al., 2015a
). In
another study the antibacterial efficacy of CH and CH NPs was compared.
Interestingly, the minimal inhibitory concentration of CH NPs was four times less
than that of CH, indicating that CH NPs at lower concentrations have antibacterial
efficacy similar to conventional CH at a higher concentration. In the agar diffusion
test the combination of CH NPs and distilled water (DW) exhibited the highest
efficacy, followed by chlorhexidine (CHX)/CH NPS, CHX/CH, and CH/DW.
When the microbial content of dentinal tubules was assessed, no significant differ-
ences were observed in 200 μm of dentinal tubules between CH NPs and CH.
However, at a depth of 400 μm, the CH NPs group exhibited a lower microbial
content when compared to CH. It seems that CH NPs can penetrate into deeper
depths of dentinal tubules (
Dianat et al., 2015b).
14.2.2 SILVER
Silver has been used since ancient times to control infection. Silver, silver ions,
and silver compounds have a strong antibacterial activity against different
microorganisms, including Escherichia coli (
Pal et al., 2007).
The toxicity of silver and silver compounds, even at low concentrations,
has been a matter of discussion . A recent study showed that 47 ppm of Ag
390 CHAPTER 14 Nanobiomaterials in endodontics

nanoparticles and 2.5% sodium hypochlorite, implanted in subcutaneous tissue
of rats, resulted in moderate chronic inflammation in 7 days, which gradual ly
and consistently decreased in severity with time. On day 15, lower concen-
trations of Ag NPs (23 ppm) provoked only a mild inflammatory response,
which was less than that with 47 ppm Ag NPs and 2.5% sodium hyp och lorite
(
Gomes-Filho et al., 2 010).
In antibacterial evaluation, 2-minute irrigation with 0.1% Ag NPs solution
exhibited no differences from saline solution and neither was effective against
Enterococcus faecalis biofilm. However, the gel form of Ag NP at 0.01%
and 0.02% concentrations and also calcium hydroxide effectively disrupted the
E. faecalis biofilm and resident bacteria in biofilm structure, with better results
achieved with 0.02% Ag NPs compared to 0.01% Ag NPs and calcium hydroxide
(
Wu et al., 2014). The Ag NPs can also be used in combination with calcium hydr-
oxide to enhance the antibacterial activity of the medicament (
Javidi et al., 2014).
It is noteworthy that discoloration and cytotoxicity of AG NPs arouse contro-
versies for their clinical application and more well-designed clinical studies
should be carried out in this area (
Garcı
´
a-Contreras et al., 2011).
14.2.3 CHITOSAN
Chitosan is a biopolymer derived from the deacetylation of chitin, with excellent
antimicrobial and antifungal activities. Chitosan is positively charged and can
bind to negatively charged surfaces of microorganisms and mucosal surfaces.
CS NPs also exhibit affinity to collagenase enzyme, which can improve
collagen stability of dentin in the long term (
Persadmehr et al., 2014). Furthermore,
in nanoparticle form chitosan has noticeable antibacterial activities.
Kishen et al.
(2008)
showed that chitosan nanoparticles can completely kill E. faecalis after
8 h. Other NPs, such as zinc oxide nanoparticles (ZnO NPs) and CS/ZnO NPs,
can also dramatically reduce the bacterial population. All the above-mentioned
NPs can reduce the adherence of E. faecalis to dentin, with the maximum
reduction with chlorhexidine followed by nanoparticles.
CS NPs are more effective than ZnO NPs against E. faecalis strains (
Shrestha
et al., 2010
). These NPs have the ability to retain their antibacterial activity even
after aging for 90 days in PBS or saliva. CS NPs and ZnO NPs both can disrupt
E. faecalis biofilm with better results with ZnO NPs (
Shrestha et al., 2010).
CS NPs can also improve the antibacterial potential of some sealers such as
zinc oxide eugenol and Therm aseal. CS NPs cannot enhance antibacterial activity
in sealers with high antibacterial properties such as mineral trioxide aggregate
(MTA) sealers (
del Carpio-Perochena et al., n.d.; Shrestha et al., 2010). In
addition, the ability of CS NPs in inactivation of bacterial endotoxins is also
limited (Shrestha et al., 2015a
).
Chitosan is also used in drug-delivery systems and in regenerative treatments,
which we address in the regeneration section.
39114.2 Nanoparticles as Irrigants and Antimicrobial Agents

14.2.4 BIOACTIVE GLASS
Bioactive glass is a glass with bone-bonding properties (Khoroushi and Keshani,
2013; Rezwan et al., 2006). In aqueous solution, ionic alkaline species are released
from the glass and elevate pH in the surrounding environment to 11.7, which is the
reason for antibacterial activity of BAG. Similar to calcium hydroxide, BAG NPs
have a slow release of alkaline components over time (Waltimo et al., 2007
).
However, a superiority of BAG NPs to calcium hydroxide is in its Ca/P precipitation
which can promote dentin remineralization (
Vollenweider et al., 2007).
Some authors reported that micrometer BAG particles had better antibacterial
activity compared to Ca(OH)
2
due to higher alkalinity of micrometer particles of
BAG. However, considering the sub-micrometric microbiota in the root canal,
these micrometer BAG particles may not be suitable for root canal dressing
(
Waltimo et al., 2009); therefore, some suggestions have been made for using
nanosized BAG in the root canal system.
There is concern about the effect of alkaline materials on the mechanical
properties of dentin. Some materials such as MTA, Ca(OH)
2
, and sodium hypo-
chlorite have a negative effect on the linkage between hydroxyapatite crystals and
dentin matrix or on the structure of dentin matrix (
Andreasen et al., 2002;
Marending et al., 2009; White et al., 2002). The comparison between BAG NPs,
Ca(OH)
2
and saline (control) on the flexural strength of dentin showed that Ca
(OH)
2
significantly reduced the flexural strength of treated dentin (35% reduction)
compared to the control group. However, the flexural strength reduction caused
by BAG NPs was not significantly different from the saline group (Marending
et al., 2009
). As mentioned above, the BAG NPs can remineralize dentin by
increasing the mineral content of the demineralized dentin but the mechanical
properties of this remineralized dentin are lower than those of natural dentin
(
Vollenweider et al., 2007).
The use of BG in tissue engineering is discussed later in this chapter.
14.3 APPLICATION OF NANOTECHNOLOGY
IN ROOT CANAL SEALERS
Sealers are one of the key components in achieving root canal seal. Sealing a
canal prevents future bacterial penetration into the root canal system and enhances
the chances of success of root canal treatment.
Most efforts in using nanoparticles in root canal sealer aim to improve the
antibacterial properties of the sealers. For this purpose, quaternary ammonium
polyethylenimine (QPEI) has been widely investigated by researchers. It is a
hydrophobic positively charged material previously showing long-lasting anti-
bacterial effects when composed with provisional cements and resin-based
materials (
Abramovitz et al., 2012; Barros et al., 2014c).
392 CHAPTER 14 Nanobiomaterials in endodontics

Both AH Plus and GuttaFlow sealers with 0.5%, 1%, or 2% concentrations of
QPEI NPs showed higher growth inhibition against E. faecalis in comparison to
unmodified sealers. Higher concentrations of QPEI were more effective than
lower dosages (
Kesler Shvero et al., 2013); however, the efficacy of QPEI added
to sealers was not so promising on the bacterial biofilm.
Joana Barros et al.
(2014b)
evaluated the effect of AH Plus sealer and Pulp Canal Sealer with and
without 2% QPEI on bacterial biofilms formed by two E. faecalis strains. The
results showed that Pulp Canal Sealer with QPEI was signif icantly better than
other materials in killing bacteria in biofilms formed by E. faecalis ATCC and
RW35 strains. AH Plus with QPEI was effective against ATCC strain but not
against RW35 strain. The effect of these materials on the biofilm biomass was
different. No material could reduce the biomass formed by RW35 strain but AH
Plus with QPEI reduced the biomass of the biofilm formed by ATCC.
QPEI alters the physicochemical and mechanical properties of sealers. Adding
QPEI to AH Plus sealer and Pulp Canal Sealer increased the wettability and
surface charge (more po sitive) of both sealers. An increase in the setting time was
seen with Pulp Canal Sealer. Interestingly, by adding QPEI, hydrophobicity of
sealers changed to hydrophilicity (
Barros et al., 2014c).
In another study the biocompatibility after adding QPEI to three different
sealers was evaluated. The results showed that QPEI at 1% concentration had no
negative effect on the biocompatibility of AH Plus, Epiphany, and GuttaFlow
sealers. However, incorporation of 2% QPEI exhibited slight toxic effects
(
Abramovitz et al., 2012). Incorporation of QPEI at 1% and 2% concentrations to
AH Plus and Pulp Canal Sealer did not influence the behavior of osteoblastic and
osteoclastic cells. However, higher concentrations of QPEI had a dose-dependent
inhibitory effect. Two percent QPEI modulated proliferation and differentiation of
osseous cells (
Joana Barros et al., 2014a).
14.4 NANOBIOMATERIALS IN ENDODONTICS
In the past decade some multipotential biomaterials were introduced to endodontics.
MTA, calcium-enriched mixture (CEM) cement (
Asgary et al., 2010), biodentine
(
Zhou et al., 2013a), and calcium phosphates have been commercially marketed and
have extensively been used. Some efforts have been made to produce and investigate
the nanoparticle size of some of these materials.
14.4.1 NANOMODIFIED MTA
Mineral trioxide aggregat e, known as MTA, is a hydrophilic material containing
mainly calcium oxide, silicon, and bismuth oxide (
Parirokh and Torabinejad,
2010; Torabinejad and White, 1998). Due to its high biocompatibility, sealing
ability, and odontogenic potential, it has gained popularity in different areas of
39314.4 Nanobiomaterials in Endodontics

endodontics (Ghasemi et al., 2014; Shahi et al., 2012, 2010). MTA has been
successfully used in pulp capping (Dominguez et al., 2003; Mente et al., 2014),
pulpotomy of deciduous and permanent teeth (Menezes et al., 2004; Shayegan
et al., 2008), root-end filling procedures (Shabahang et al., 1999; Tawil et al.,
2009), perforation repair (Al-Daafas and Al-Nazhan, 2007
), root coronal barrier
formation (
Mohammadi and Khademi, 2006), and recently in regeneration
treatments (
Banchs and Trope, 2004). However, MTA still has some drawbacks,
especially in handling; it also has a complex setting reaction (
Darvell and Wu,
2011
). Furthermore, acidic environments or solutions reduc e the microhardness
and increase the porosity of MTA (
Namazikhah et al., 2008; Saghiri et al., 2008).
Komabayashi and Spa
˚
ngberg showed that MTA’s particle size has a great
impact on the extent of particles penetrating into dentinal tubules. Particle size
also affects the dicalcium and tricalcium silicate particle reactivity and conse-
quently the porosity of the cement (
Komabayashi and Spa
˚
ngberg, 2008a,b).
Recently, nanomodified white MTA (NWMTA) has been patented by Saghiri
et al. (2012a,b) (Table 14.1
). The inventors claim that NWMTA exhibits “higher
resistance to acidic environments, higher durability in the face of ambient
changes, better hydration ability, better inertness toward toxic ambience, better
stability with regard to organic and inorganic contaminants, better strength, less
expansion, lower porosity, improved interfacial mi crostructure, induction of
hydroxyapatite formulation, better biocompatibility, quicker setting time, espe-
cially in an aqueous environment, quicker stimulation of hard tissue healing,
superior microhardness owing to the presence of nanoparticles, a smoother
surface that enables better adhesion to the tooth structure and less gaps, improved
cementogenesis and higher osteoconductivity” when compared to other similar
products such as MTA and Portland cement.
The particle sizes in NWMTA are 40100 nm. Reduced particle size in
NWMTA provides a surface area about four times higher than that of WMTA,
enhancing hydration reactions; as a result, the initial setting time decreased from
40 min in WMTA to 6 min in NWMTA (
Saghiri et al., 2012a,b).
Table 14.1 Components of NWMTA (Saghiri et al., 2012a,b)
Ingredient Formula Percentage
Disodium hydrogen phosphate Na
2
HPO
4
2
Bismuth oxide (bismite) Bi
2
O
3
17
Tricalcium silicate (hatrurite) Ca
3
SiO
5
50
Dicalcium silicate (larnite) Ca
2
SiO
4
15
Calcium sulfate (anhydrite) CaSo
4
2
Gypsum CaSo
4
2H
2
O5
Strontium carbonate SrCo
3
3
Zeolite M
2
/nOA
12
O
3
xSiO
2
yH
2
O2
Tricalcium aluminate Ca
3
Al
2
O
6
4
394 CHAPTER 14 Nanobiomaterials in endodontics

In comparison to WMTA, four new ingredients have been added to NWMTA.
These ingredients are tricalcium aluminate, calcium sulfate, zeolite, and strontium
carbonate. Tricalcium aluminate is used for flash setting. However, flash setting
is associated with an increase in heat; therefore, the amount of tricalcium alumi-
nate in the composition should be limited (
Saghiri et al., 2014).
The newly added strontium carbonate in the composition of NWMTA helps
uniform distribution of ingredients via preventing particle agglomeration. It also
reduces the setting time and increases the bioactivity of the cement (
Saghiri et al.,
2012a,b). Energy-dispersive spectroscopy dot map showed WMTA to have no
strontium in its composition (Saghiri et al., 2012a,b).
Zeolite is a crystalline hydrated aluminosilicate of alkaline metals and metals
of alkaline soils (Ca, K, Na, Mg). It works as an anticorrosive and stabilizing
component of NWMTA (
Saghiri et al., 2014). Anticorrosive components of
NWMTA such as zeolite can reduce the effect of sulfate attack during the setting
reaction (
Saghiri et al., 2013).
NWMTA has two times less porosity due to its nanosized particles, leading to
reduced crack propagation and acid penetration into the surface texture compared
with WMTA (
Saghiri et al., 2012a,b). In acidic environments NWMTA has
shown some cement loss (Saghiri et al., 2014
) but it has higher microhardness in
acidic conditions in comparison to WMTA. In fact at a pH value of 7.4, the
microhardness of NWMTA and WMTA were 81.53 6 2.62 and 51.31 6 1.14,
respectively; in the acidic environment (pH 5 4.4) the microhardness of both
cements decreased to 54.59 6 1.08 for NWMTA and 16.10 6 2.84 for WMTA
(
Saghiri et al., 2012a,b).
In another study the effect of different pH values on the compressive strength
of NWMTA, WMTA, and Bioaggregate was evaluated. The results showed that
all the tested materials showed their highest compressive strength in alkaline pH
(pH 5 10.4), which were 133.19, 103.63, and 29.07 for NWMTA, WMTA, and
Bioaggregate, respectively. Lowering the pH to 7.4 decreased the compressive
strength of NWMTA, WMTA, and Bioaggregate to 126.81, 86.23, and 25.36,
respectively. The lowest compressive strength of tested materials was in acidic pH
(pH 5 4.4). The compressive strengths of 111.41, 63.78, and 10.88 were recorded
for NWMTA, WMTA, and Bioaggregate, respectively. In conclusion, NWMTA
exhibited the highest compressive strength at all the three pH levels (
Saghiri et al.,
2013
). When the solubility of NWMTA, WMTA, and Bioaggregate was evaluated
under the same pH, the results showed that at a pH value of 10.4, all the tested
materials had comparable solubility. However, when the pH value decreased to 7.4,
NWMTA exhibited significantly lower solubility compared to Bioaggregate. At a
pH value of 4.4, both Bioggreage and MTA groups exhibited significantly higher
solubility compared to NWMTA (
Saghiri et al., 2014).
There were some concerns that the faster hydration of NWMTA might result
in cement dislodgment in the tooth (
Saghiri et al., 2012a,b). More recent research
showed that NWMTA exhibits better adhesive bonding to dentin and a higher
push-out bond strength than WMTA ( Saghiri et al., 2013
). Despite this superb
39514.4 Nanobiomaterials in Endodontics

characteristic of NWMTA, push-out strength of the material significantly
decreased in thermocycling test (
Saghiri et al., 2013).
It seems NWMTA is very biocompatible. As compare d to WMTA, NWMTA
had better inflammatory response and bone regeneration properties (
Saghiri et al.,
2015c
); however, a better bone healing response was seen when nanotricalcium
aluminate was added to NMTA (
Saghiri et al., 2014).
WMTA
Portland
Cement
Dental Cement of the
Present Invention
Water-to-cement 1:3 1:3 1:2 to 1:3
Powder ratio needed
Setting time (min) 39.1 139.1 6.2
Microhardness 52.21 29.32 85.21
At pH 5 7.4
Microhardness 13.98 13.14 72.21
At pH 5 4.4
Leakage (ng/ml) 0.282 6 0.079 0.410 6 0.093 0.012 6 0.011
Calcium ion content in NWMTA is 80%, which is higher than that in WMTA
(5075%). On the other hand, the increase in total surface of NWMTA and
improvement in hydration of cement particles leads to an increase in calcium
hydroxide formation. Both these phenomena enhance calcium release from the
material and elevate the pH value in the peripheral environment of NWMTA
(
Saghiri et al., 2015a).
Another change made in MTA is a change in the particle size of bismuth oxide
to nanosize. Hydrated MTA has a weaker microstructure than Portland cement
(
Camilleri, 2007). It seems that some additives in MTA, such as bismuth oxide, do
not contribute to hydration reactions and ultimately increase the porosity of the
cement and decrease the compressive strength of the cement (
Coomaraswamy
et al., 2007
). In the same manner, tricalcium silicate cement (CSC), with properties
similar to those of MTA, showed higher physical properties than CSC with 10%
bismuth oxide (
Coomaraswamy et al., 2007; Saghiri et al., 2015b). However,
adding 10% nano-bismuth oxide to the CSCs significantly enhanced the com-
pressive strength and microhardness of the cement compared to that of CSCs and
CSCs with 10% regular size bismuth oxide (Saghiri et al., 2015b
).
14.4.1.1 Bioaggregate
Bioaggregate is a calcium-silicate-based material composed of nanosized particles
with similar main components and indications for use with WMTA. It was devel-
oped by Innovative BioCaramix Inc. (Vancouver, BC, Canada). The main dif-
ference between the two cements in their composition is in elimination of
aluminum from Bioaggregate. This cement is known as the first repair cement
in endodontics with nanosized particles (
De-Deus et al., 2009). The chief
396 CHAPTER 14 Nanobiomaterials in endodontics

components of Bioaggregate are tricalcium silicate, dicalcium silicate, tantalum
pentoxide, and calcium phosphate monobasic.
Tantalum pentoxide is used as a radiopacifer and is a substitute for bismuth
oxide in MTA (
Zhang et al., 2009). Tanta lum pentoxide is an inert material which
is mostly used in the orthopedic field. X-ray diffraction (XRD) evaluation of set
and fresh powder of Bioaggregate showed a high peak of tantalum oxide calcium
silicate oxide, calcium silicate, hydroxyapatite, quartz, and calcium phosphate
silicate. Calcite and calcium hydroxide were observed in set form of the cement
but no t in the fresh powder (
Park et al., 2010). In fact, similar to MTA, calcium
silicate hydrate and c alcium hydroxide are two of the final products of the
hydration reaction of Bioaggregate ce ment (
Zhang et al., 2009). Another study
showed some phosphorus in the compos ition of Bioaggregate in EDX analysis
but it was not co nfi rmed in scanning electron micrographs (
Grech et al., 2013).
Calcium aluminum oxide, calcium magnesium aluminum oxide, and bismuth
oxide are three materials of MTA, which have been eliminated from
Bioaggregate composition (
Park et al., 2010).
The pH of Bioaggregate was comparable to that of tricalcium silicate cement
(Mineral Research Processing, Meyzieu, France) and Biodentinet (Septodont,
Saint-Maur-des-fosse
´
s Cedex, France). But the calcium ion release of Bioaggregate
was significantly lower than others. All the tested materials reached their highest
level of calcium release by day 14 (
Grech et al., 2013).
De-Deus et al. compared the cytocompatiblity of Bioaggregate cement with
MTA as a root-end filling material. The results showed that human mesenchymal
cells have cytocompatibility responses comparable to the cements (
De-Deus et al.,
2009
). The cytotoxicity assay of Bioaggregate and MTA cements to MC3T3-E1
cell lines showed similar viability and proliferation patterns between cements on
days 1 to 3. Bioaggregate and MTA suppressed the expression of collagen type I,
osteocalcine, and osteopontin genes on the first day. On the second and third days
Bioaggregate showed similar or higher gene expression than MTA. It is supposed
that high pH of freshly mixed cements inhibits the gene expression on the first day.
It seems differences in the composition and speed of ions released between
Bioaggregate and MTA affect the expression of mineral-associated genes in
MC3T3-E1 cells (
Yuan et al., 2010).
However, the cytotoxicity of Bioaggregate and MTA to human periodontal
ligament fibroblasts was very similartothatofMC3T3-E1cells.Whenthe
expression o f alk aline p hosp ha tase gene was evaluated, the results showed that
MTA upregulate d the ALP a ctivity on da y 3 but not on days 5 and 7. On the
other hand, Bioaggregate upregulated the ALP activity on day 7 but not on pre-
vious d ays. Col 1 expression wa s a little diffe rent. MTA and Bioaggregate
increased the expression of Col 1 expression on days 3 and 5 and days 5 and 7,
respectively (
Yan et al., 2010).
Zhang et al. showed that Bioaggregate and MTA can increase the activity of
ALP and expression of odontoblastic differentiation genes (OC, DSPP, and
DMP-1) of hDPSCs from day 1 to day 7. Only on day 7, was the ALP activity in
39714.4 Nanobiomaterials in Endodontics

the Bioaggregate group significantly higher than that in the MTA group. In
comparison to MTA Bioaggregate gene upregulation was higher for DSPP on day
7 and for DMP-1 on days 5 and 7 (
Zhang et al., 2013). These findings were
consistent with a recent research which showed excellent cytocompatibility of
Bioaggregate. In this study Cell Counting Kit-8 Assay (CCK-8) was used to
assess the cell viability of hDPSCs exposed to different dilutions of Bioaggregate
and MTA. The results showed that in 24 h the cell viability of the undiluted
Bioaggregate group was significantly higher than that of the control, diluted
Bioaggregate, and diluted and undiluted MTA groups. At 48-h interval, treating
the cells with undiluted Bioaggregate and undiluted MTA caused a significant
increase and decrease in viable cells, respectively. All dilutions of MTA reduced
the cell viability in 72 h. At 24-, 48-, and 72-h intervals, cell viability of undiluted
Bioaggregate was higher than that of MTA. Cell adhesion and cell migration
of undiluted Bioaggregate was also higher than that of the MTA group. It is
noteworthy that in comparison to the control group, only undiluted Bioaggregate
could enhance cell adhesion; however, cell migration was enhanced by all the
dilutions of Bioaggregate and MTA. SEM images showed that Bioaggregate-
treated cells were more flattened and exhibited better spreading compared to
MTA-treated cells. The authors believed that hydroxyapatite formation after
hydration in Bioaggregate cement resulted in superior cytocompatibility of
Bioaggregate compared to MTA. Therefore Bioaggregate coul d be considered an
alternative to MTA in direct pulp-capping procedures (
Zhu et al., 2014).
Chang et al. showed that hDPSC viability adjacent to Bioaggregate was
enhanced over time. Bioaggregate also increased ALP activity, mineralization,
and mRNA expression of some odontogenic markers such as ALP, OC, dSPP,
and DMP-1 in a time-dependent manner (
Chang et al., 2014).
Evaluation of the effect of Bioaggregate on kidney and liver showed that in
comparison to the control group the amount of inflammatory cells had significantly
increased on day 7. On this day, an increase in Kupffer cells, distortion, and dilata-
tion in the hepatic portal vein (HPV) with rupture in the endothelial lining of the
vein and congestion of the sinusoidal spaces were seen in the liver. In the kidney,
changes in the Malpighian corpuscles of renal cortex, debris of degenerated
glomeruli, changes, and distortion in nuclei of the visceral layer of Bowman’s
capsules, and vacuolation of cytoplasm of the distal convoluted tubules (DCTs)
were prominent. In both kidney and liver, collagen deposition was enhanced.
On day 30, inflammatory responses had significantly reduced. The kidney and
liver had recovered to some extent. However, dilation of the central vein of the
liver and some abnormality in hepatocytes still existed. Hemorrhage could still be
seen in some areas of kidney. Collagen fibers were normal.
Biochemical tests of liver and kidney also showed some changes.
Bioaggregate resulted in an increase in aspartate aminotransferase (AST) level on
days 7 and 30 compared to the control group. However, the level of AST was
significantly lower on day 30 compared to day 7. On the contrary, alanine amino-
transferase (ALT) of the Bioaggregate group exhibited no differences from
398 CHAPTER 14 Nanobiomaterials in endodontics

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CHAPTER14Nanobiomaterialsin endodonticsMaryam Khoroushi1, Abbas Ali Khademi2, M az iar Ebrahimi Dastgurdi3andMajid Abdolrahi mi41Dental Materials Research Center and Department of Operative Dentistry, School of Dentistry,Isfahan University of Medical Sciences, Isfahan, Iran2Torabinejad Dental Research Center andDepartment of Endodontics, School of Dentistry, Isfahan University of Medical Sciences,Isfahan, Iran3Maxillofacial Stem Cells Research Center and Department of Endodontics,School of Dentistry, Islamic Azad University, Isfahan (Khorasgan Branch), Isfahan, Iran4School of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran14.1 INTRODUCTIONSince World War II, when Dr Orban described pulpal pathosis, endodontictreatments have progressively become more popular among and accepted bypatients and dentists. Root canal therapy (RCT) as the most commonly per-formed treatment in endodontics is based on mechanical and chemical clean-ing a nd shaping of the canal and filling the canal with inert materials. O verthe past decades, improvements in techniques, instruments, and materials h avedramatically increased the success rate of RCTs.On the other hand, regenerative concepts have opened new horizons toendodontic treatments. In regenerative procedures the main goal is not toremove the pulp and fill the canal but to retain the pulp tissue and provoke therepair mechanism o f the pulp (such as direct pulp c appin g or ape xoge nesisprocedure) or to provoke the existing stem cells to produce new vital pulptissue in the canal (such as the revascularization procedure).Nano-sizing improves the bioavailability and bioactivity of the materials. Inendodontics, r esearchers have studied using these nanosized materials in differ-ent areas of endodontics. Nanoparticles in irrigat ion solutions and obturatingmaterials, in osteoconductive a nd osteoinductive materials, in drug-deliverysystems and in scaffolds are some of the possible applications of nanomaterialsin endodontics.In this chapter we will review some of the recent developments in nano-materials used in endodontics.389Nanobiomaterials in Dentistry. DOI: http://dx.doi.org/10.1016/B978-0-323-42867-5.00014-X© 2016 Elsevier Inc. All rights reserved. 14.2 NANOPARTICLES AS IRRIGANTSAND ANTIMICROBIAL AGENTSDisinfection of the root canal system plays a key role in the success of root canaltreatment. Various irrigants and medicaments with different antibacterial activitiesand physical properties have been used in endodontics. Despite outstanding proper-ties of many of these irrigants and medicaments, none of them has all the idealcharacteristics of an antibacterial agent. Therefore, efforts have focused on improv-ing the properties of the existing irrigants and medicaments and one of the ways toachieve this goal is reducing the particle size of these agents to the nano-scale.The higher surface area and charge density of nanoparticles enable them to moreefficiently interact with bacterial cells and give them more antibacterial potentialcompared to antibacterial powders (Kishen et al., 2008; Yamamoto, 2001). Theyhave broad-spectrum antibacterial activity and lower potential for provoking bacterialresistance (Kishen, 2010). Silver, zinc oxide, chitosan, bioactive glass, and calciumhydroxide are some materials with high antibacterial activity as nanoparticles.14.2.1 CALCIUM HYDROXIDEFor many years calcium hydroxide nanoparticles (CH NPs) have been investigatedin different fields of science (Roy and Bhattacharya, 2010; Salvadori and Dei,2001) but studies on CH NPs are limited in dentistry. Comparison of cytotoxicityof CH and CH NPs on fibroblast cell lines showed that CH and CH NPs havecomparable cytotoxic effects at 24, 48, and 72 h. Both types of CH had a signifi-cantly lower toxicity at 72 h compared to 24 and 48 h (Dianat et al., 2015a). Inanother study the antibacterial efficacy of CH and CH NPs was compared.Interestingly, the minimal inhibitory concentration of CH NPs was four times lessthan that of CH, indicating that CH NPs at lower concentrations have antibacterialefficacy similar to conventional CH at a higher concentration. In the agar diffusiontest the combination of CH NPs and distilled water (DW) exhibited the highestefficacy, followed by chlorhexidine (CHX)/CH NPS, CHX/CH, and CH/DW.When the microbial content of dentinal tubules was assessed, no significant differ-ences were observed in 200 μm of dentinal tubules between CH NPs and CH.However, at a depth of 400 μm, the CH NPs group exhibited a lower microbialcontent when compared to CH. It seems that CH NPs can penetrate into deeperdepths of dentinal tubules (Dianat et al., 2015b).14.2.2 SILVERSilver has been used since ancient times to control infection. Silver, silver ions,and silver compounds have a strong antibacterial activity against differentmicroorganisms, including Escherichia coli (Pal et al., 2007).The toxicity of silver and silver compounds, even at low concentrations,has been a matter of discussion . A recent study showed that 47 ppm of Ag390 CHAPTER 14 Nanobiomaterials in endodontics nanoparticles and 2.5% sodium hypochlorite, implanted in subcutaneous tissueof rats, resulted in moderate chronic inflammation in 7 days, which gradual lyand consistently decreased in severity with time. On day 15, lower concen-trations of Ag NPs (23 ppm) provoked only a mild inflammatory response,which was less than that with 47 ppm Ag NPs and 2.5% sodium hyp och lorite(Gomes-Filho et al., 2 010).In antibacterial evaluation, 2-minute irrigation with 0.1% Ag NPs solutionexhibited no differences from saline solution and neither was effective againstEnterococcus faecalis biofilm. However, the gel form of Ag NP at 0.01%and 0.02% concentrations and also calcium hydroxide effectively disrupted theE. faecalis biofilm and resident bacteria in biofilm structure, with better resultsachieved with 0.02% Ag NPs compared to 0.01% Ag NPs and calcium hydroxide(Wu et al., 2014). The Ag NPs can also be used in combination with calcium hydr-oxide to enhance the antibacterial activity of the medicament (Javidi et al., 2014).It is noteworthy that discoloration and cytotoxicity of AG NPs arouse contro-versies for their clinical application and more well-designed clinical studiesshould be carried out in this area (Garcı´a-Contreras et al., 2011).14.2.3 CHITOSANChitosan is a biopolymer derived from the deacetylation of chitin, with excellentantimicrobial and antifungal activities. Chitosan is positively charged and canbind to negatively charged surfaces of microorganisms and mucosal surfaces.CS NPs also exhibit affinity to collagenase enzyme, which can improvecollagen stability of dentin in the long term (Persadmehr et al., 2014). Furthermore,in nanoparticle form chitosan has noticeable antibacterial activities.Kishen et al.(2008)showed that chitosan nanoparticles can completely kill E. faecalis after8 h. Other NPs, such as zinc oxide nanoparticles (ZnO NPs) and CS/ZnO NPs,can also dramatically reduce the bacterial population. All the above-mentionedNPs can reduce the adherence of E. faecalis to dentin, with the maximumreduction with chlorhexidine followed by nanoparticles.CS NPs are more effective than ZnO NPs against E. faecalis strains (Shresthaet al., 2010). These NPs have the ability to retain their antibacterial activity evenafter aging for 90 days in PBS or saliva. CS NPs and ZnO NPs both can disruptE. faecalis biofilm with better results with ZnO NPs (Shrestha et al., 2010).CS NPs can also improve the antibacterial potential of some sealers such aszinc oxide eugenol and Therm aseal. CS NPs cannot enhance antibacterial activityin sealers with high antibacterial properties such as mineral trioxide aggregate(MTA) sealers (del Carpio-Perochena et al., n.d.; Shrestha et al., 2010). Inaddition, the ability of CS NPs in inactivation of bacterial endotoxins is alsolimited (Shrestha et al., 2015a).Chitosan is also used in drug-delivery systems and in regenerative treatments,which we address in the regeneration section.39114.2 Nanoparticles as Irrigants and Antimicrobial Agents 14.2.4 BIOACTIVE GLASSBioactive glass is a glass with bone-bonding properties (Khoroushi and Keshani,2013; Rezwan et al., 2006). In aqueous solution, ionic alkaline species are releasedfrom the glass and elevate pH in the surrounding environment to 11.7, which is thereason for antibacterial activity of BAG. Similar to calcium hydroxide, BAG NPshave a slow release of alkaline components over time (Waltimo et al., 2007).However, a superiority of BAG NPs to calcium hydroxide is in its Ca/P precipitationwhich can promote dentin remineralization (Vollenweider et al., 2007).Some authors reported that micrometer BAG particles had better antibacterialactivity compared to Ca(OH)2due to higher alkalinity of micrometer particles ofBAG. However, considering the sub-micrometric microbiota in the root canal,these micrometer BAG particles may not be suitable for root canal dressing(Waltimo et al., 2009); therefore, some suggestions have been made for usingnanosized BAG in the root canal system.There is concern about the effect of alkaline materials on the mechanicalproperties of dentin. Some materials such as MTA, Ca(OH)2, and sodium hypo-chlorite have a negative effect on the linkage between hydroxyapatite crystals anddentin matrix or on the structure of dentin matrix (Andreasen et al., 2002;Marending et al., 2009; White et al., 2002). The comparison between BAG NPs,Ca(OH)2and saline (control) on the flexural strength of dentin showed that Ca(OH)2significantly reduced the flexural strength of treated dentin (35% reduction)compared to the control group. However, the flexural strength reduction causedby BAG NPs was not significantly different from the saline group (Marendinget al., 2009). As mentioned above, the BAG NPs can remineralize dentin byincreasing the mineral content of the demineralized dentin but the mechanicalproperties of this remineralized dentin are lower than those of natural dentin(Vollenweider et al., 2007).The use of BG in tissue engineering is discussed later in this chapter.14.3 APPLICATION OF NANOTECHNOLOGYIN ROOT CANAL SEALERSSealers are one of the key components in achieving root canal seal. Sealing acanal prevents future bacterial penetration into the root canal system and enhancesthe chances of success of root canal treatment.Most efforts in using nanoparticles in root canal sealer aim to improve theantibacterial properties of the sealers. For this purpose, quaternary ammoniumpolyethylenimine (QPEI) has been widely investigated by researchers. It is ahydrophobic positively charged material previously showing long-lasting anti-bacterial effects when composed with provisional cements and resin-basedmaterials (Abramovitz et al., 2012; Barros et al., 2014c).392 CHAPTER 14 Nanobiomaterials in endodontics Both AH Plus and GuttaFlow sealers with 0.5%, 1%, or 2% concentrations ofQPEI NPs showed higher growth inhibition against E. faecalis in comparison tounmodified sealers. Higher concentrations of QPEI were more effective thanlower dosages (Kesler Shvero et al., 2013); however, the efficacy of QPEI addedto sealers was not so promising on the bacterial biofilm.Joana Barros et al.(2014b)evaluated the effect of AH Plus sealer and Pulp Canal Sealer with andwithout 2% QPEI on bacterial biofilms formed by two E. faecalis strains. Theresults showed that Pulp Canal Sealer with QPEI was signif icantly better thanother materials in killing bacteria in biofilms formed by E. faecalis ATCC andRW35 strains. AH Plus with QPEI was effective against ATCC strain but notagainst RW35 strain. The effect of these materials on the biofilm biomass wasdifferent. No material could reduce the biomass formed by RW35 strain but AHPlus with QPEI reduced the biomass of the biofilm formed by ATCC.QPEI alters the physicochemical and mechanical properties of sealers. AddingQPEI to AH Plus sealer and Pulp Canal Sealer increased the wettability andsurface charge (more po sitive) of both sealers. An increase in the setting time wasseen with Pulp Canal Sealer. Interestingly, by adding QPEI, hydrophobicity ofsealers changed to hydrophilicity (Barros et al., 2014c).In another study the biocompatibility after adding QPEI to three differentsealers was evaluated. The results showed that QPEI at 1% concentration had nonegative effect on the biocompatibility of AH Plus, Epiphany, and GuttaFlowsealers. However, incorporation of 2% QPEI exhibited slight toxic effects(Abramovitz et al., 2012). Incorporation of QPEI at 1% and 2% concentrations toAH Plus and Pulp Canal Sealer did not influence the behavior of osteoblastic andosteoclastic cells. However, higher concentrations of QPEI had a dose-dependentinhibitory effect. Two percent QPEI modulated proliferation and differentiation ofosseous cells (Joana Barros et al., 2014a).14.4 NANOBIOMATERIALS IN ENDODONTICSIn the past decade some multipotential biomaterials were introduced to endodontics.MTA, calcium-enriched mixture (CEM) cement (Asgary et al., 2010), biodentine(Zhou et al., 2013a), and calcium phosphates have been commercially marketed andhave extensively been used. Some efforts have been made to produce and investigatethe nanoparticle size of some of these materials.14.4.1 NANOMODIFIED MTAMineral trioxide aggregat e, known as MTA, is a hydrophilic material containingmainly calcium oxide, silicon, and bismuth oxide (Parirokh and Torabinejad,2010; Torabinejad and White, 1998). Due to its high biocompatibility, sealingability, and odontogenic potential, it has gained popularity in different areas of39314.4 Nanobiomaterials in Endodontics endodontics (Ghasemi et al., 2014; Shahi et al., 2012, 2010). MTA has beensuccessfully used in pulp capping (Dominguez et al., 2003; Mente et al., 2014),pulpotomy of deciduous and permanent teeth (Menezes et al., 2004; Shayeganet al., 2008), root-end filling procedures (Shabahang et al., 1999; Tawil et al.,2009), perforation repair (Al-Daafas and Al-Nazhan, 2007), root coronal barrierformation (Mohammadi and Khademi, 2006), and recently in regenerationtreatments (Banchs and Trope, 2004). However, MTA still has some drawbacks,especially in handling; it also has a complex setting reaction (Darvell and Wu,2011). Furthermore, acidic environments or solutions reduc e the microhardnessand increase the porosity of MTA (Namazikhah et al., 2008; Saghiri et al., 2008).Komabayashi and Spa˚ngberg showed that MTA’s particle size has a greatimpact on the extent of particles penetrating into dentinal tubules. Particle sizealso affects the dicalcium and tricalcium silicate particle reactivity and conse-quently the porosity of the cement (Komabayashi and Spa˚ngberg, 2008a,b).Recently, nanomodified white MTA (NWMTA) has been patented by Saghiriet al. (2012a,b) (Table 14.1). The inventors claim that NWMTA exhibits “higherresistance to acidic environments, higher durability in the face of ambientchanges, better hydration ability, better inertness toward toxic ambience, betterstability with regard to organic and inorganic contaminants, better strength, lessexpansion, lower porosity, improved interfacial mi crostructure, induction ofhydroxyapatite formulation, better biocompatibility, quicker setting time, espe-cially in an aqueous environment, quicker stimulation of hard tissue healing,superior microhardness owing to the presence of nanoparticles, a smoothersurface that enables better adhesion to the tooth structure and less gaps, improvedcementogenesis and higher osteoconductivity” when compared to other similarproducts such as MTA and Portland cement.The particle sizes in NWMTA are 40100 nm. Reduced particle size inNWMTA provides a surface area about four times higher than that of WMTA,enhancing hydration reactions; as a result, the initial setting time decreased from40 min in WMTA to 6 min in NWMTA (Saghiri et al., 2012a,b).Table 14.1 Components of NWMTA (Saghiri et al., 2012a,b)Ingredient Formula PercentageDisodium hydrogen phosphate Na2HPO42Bismuth oxide (bismite) Bi2O317Tricalcium silicate (hatrurite) Ca3SiO550Dicalcium silicate (larnite) Ca2SiO415Calcium sulfate (anhydrite) CaSo42Gypsum CaSo4•2H2O5Strontium carbonate SrCo33Zeolite M2/nO•A12O3•xSiO2•yH2O2Tricalcium aluminate Ca3Al2O64394 CHAPTER 14 Nanobiomaterials in endodontics In comparison to WMTA, four new ingredients have been added to NWMTA.These ingredients are tricalcium aluminate, calcium sulfate, zeolite, and strontiumcarbonate. Tricalcium aluminate is used for flash setting. However, flash settingis associated with an increase in heat; therefore, the amount of tricalcium alumi-nate in the composition should be limited (Saghiri et al., 2014).The newly added strontium carbonate in the composition of NWMTA helpsuniform distribution of ingredients via preventing particle agglomeration. It alsoreduces the setting time and increases the bioactivity of the cement (Saghiri et al.,2012a,b). Energy-dispersive spectroscopy dot map showed WMTA to have nostrontium in its composition (Saghiri et al., 2012a,b).Zeolite is a crystalline hydrated aluminosilicate of alkaline metals and metalsof alkaline soils (Ca, K, Na, Mg). It works as an anticorrosive and stabilizingcomponent of NWMTA (Saghiri et al., 2014). Anticorrosive components ofNWMTA such as zeolite can reduce the effect of sulfate attack during the settingreaction (Saghiri et al., 2013).NWMTA has two times less porosity due to its nanosized particles, leading toreduced crack propagation and acid penetration into the surface texture comparedwith WMTA (Saghiri et al., 2012a,b). In acidic environments NWMTA hasshown some cement loss (Saghiri et al., 2014) but it has higher microhardness inacidic conditions in comparison to WMTA. In fact at a pH value of 7.4, themicrohardness of NWMTA and WMTA were 81.53 6 2.62 and 51.31 6 1.14,respectively; in the acidic environment (pH 5 4.4) the microhardness of bothcements decreased to 54.59 6 1.08 for NWMTA and 16.10 6 2.84 for WMTA(Saghiri et al., 2012a,b).In another study the effect of different pH values on the compressive strengthof NWMTA, WMTA, and Bioaggregate was evaluated. The results showed thatall the tested materials showed their highest compressive strength in alkaline pH(pH 5 10.4), which were 133.19, 103.63, and 29.07 for NWMTA, WMTA, andBioaggregate, respectively. Lowering the pH to 7.4 decreased the compressivestrength of NWMTA, WMTA, and Bioaggregate to 126.81, 86.23, and 25.36,respectively. The lowest compressive strength of tested materials was in acidic pH(pH 5 4.4). The compressive strengths of 111.41, 63.78, and 10.88 were recordedfor NWMTA, WMTA, and Bioaggregate, respectively. In conclusion, NWMTAexhibited the highest compressive strength at all the three pH levels (Saghiri et al.,2013). When the solubility of NWMTA, WMTA, and Bioaggregate was evaluatedunder the same pH, the results showed that at a pH value of 10.4, all the testedmaterials had comparable solubility. However, when the pH value decreased to 7.4,NWMTA exhibited significantly lower solubility compared to Bioaggregate. At apH value of 4.4, both Bioggreage and MTA groups exhibited significantly highersolubility compared to NWMTA (Saghiri et al., 2014).There were some concerns that the faster hydration of NWMTA might resultin cement dislodgment in the tooth (Saghiri et al., 2012a,b). More recent researchshowed that NWMTA exhibits better adhesive bonding to dentin and a higherpush-out bond strength than WMTA ( Saghiri et al., 2013). Despite this superb39514.4 Nanobiomaterials in Endodontics characteristic of NWMTA, push-out strength of the material significantlydecreased in thermocycling test (Saghiri et al., 2013).It seems NWMTA is very biocompatible. As compare d to WMTA, NWMTAhad better inflammatory response and bone regeneration properties (Saghiri et al.,2015c); however, a better bone healing response was seen when nanotricalciumaluminate was added to NMTA (Saghiri et al., 2014).WMTAPortlandCementDental Cement of thePresent InventionWater-to-cement 1:3 1:3 1:2 to 1:3Powder ratio neededSetting time (min) 39.1 139.1 6.2Microhardness 52.21 29.32 85.21At pH 5 7.4Microhardness 13.98 13.14 72.21At pH 5 4.4Leakage (ng/ml) 0.282 6 0.079 0.410 6 0.093 0.012 6 0.011Calcium ion content in NWMTA is 80%, which is higher than that in WMTA(5075%). On the other hand, the increase in total surface of NWMTA andimprovement in hydration of cement particles leads to an increase in calciumhydroxide formation. Both these phenomena enhance calcium release from thematerial and elevate the pH value in the peripheral environment of NWMTA(Saghiri et al., 2015a).Another change made in MTA is a change in the particle size of bismuth oxideto nanosize. Hydrated MTA has a weaker microstructure than Portland cement(Camilleri, 2007). It seems that some additives in MTA, such as bismuth oxide, donot contribute to hydration reactions and ultimately increase the porosity of thecement and decrease the compressive strength of the cement (Coomaraswamyet al., 2007). In the same manner, tricalcium silicate cement (CSC), with propertiessimilar to those of MTA, showed higher physical properties than CSC with 10%bismuth oxide (Coomaraswamy et al., 2007; Saghiri et al., 2015b). However,adding 10% nano-bismuth oxide to the CSCs significantly enhanced the com-pressive strength and microhardness of the cement compared to that of CSCs andCSCs with 10% regular size bismuth oxide (Saghiri et al., 2015b).14.4.1.1 BioaggregateBioaggregate is a calcium-silicate-based material composed of nanosized particleswith similar main components and indications for use with WMTA. It was devel-oped by Innovative BioCaramix Inc. (Vancouver, BC, Canada). The main dif-ference between the two cements in their composition is in elimination ofaluminum from Bioaggregate. This cement is known as the first repair cementin endodontics with nanosized particles (De-Deus et al., 2009). The chief396 CHAPTER 14 Nanobiomaterials in endodontics components of Bioaggregate are tricalcium silicate, dicalcium silicate, tantalumpentoxide, and calcium phosphate monobasic.Tantalum pentoxide is used as a radiopacifer and is a substitute for bismuthoxide in MTA (Zhang et al., 2009). Tanta lum pentoxide is an inert material whichis mostly used in the orthopedic field. X-ray diffraction (XRD) evaluation of setand fresh powder of Bioaggregate showed a high peak of tantalum oxide calciumsilicate oxide, calcium silicate, hydroxyapatite, quartz, and calcium phosphatesilicate. Calcite and calcium hydroxide were observed in set form of the cementbut no t in the fresh powder (Park et al., 2010). In fact, similar to MTA, calciumsilicate hydrate and c alcium hydroxide are two of the final products of thehydration reaction of Bioaggregate ce ment (Zhang et al., 2009). Another studyshowed some phosphorus in the compos ition of Bioaggregate in EDX analysisbut it was not co nfi rmed in scanning electron micrographs (Grech et al., 2013).Calcium aluminum oxide, calcium magnesium aluminum oxide, and bismuthoxide are three materials of MTA, which have been eliminated fromBioaggregate composition (Park et al., 2010).The pH of Bioaggregate was comparable to that of tricalcium silicate cement(Mineral Research Processing, Meyzieu, France) and Biodentinet (Septodont,Saint-Maur-des-fosse´s Cedex, France). But the calcium ion release of Bioaggregatewas significantly lower than others. All the tested materials reached their highestlevel of calcium release by day 14 (Grech et al., 2013).De-Deus et al. compared the cytocompatiblity of Bioaggregate cement withMTA as a root-end filling material. The results showed that human mesenchymalcells have cytocompatibility responses comparable to the cements (De-Deus et al.,2009). The cytotoxicity assay of Bioaggregate and MTA cements to MC3T3-E1cell lines showed similar viability and proliferation patterns between cements ondays 1 to 3. Bioaggregate and MTA suppressed the expression of collagen type I,osteocalcine, and osteopontin genes on the first day. On the second and third daysBioaggregate showed similar or higher gene expression than MTA. It is supposedthat high pH of freshly mixed cements inhibits the gene expression on the first day.It seems differences in the composition and speed of ions released betweenBioaggregate and MTA affect the expression of mineral-associated genes inMC3T3-E1 cells (Yuan et al., 2010).However, the cytotoxicity of Bioaggregate and MTA to human periodontalligament fibroblasts was very similartothatofMC3T3-E1cells.Whentheexpression o f alk aline p hosp ha tase gene was evaluated, the results showed thatMTA upregulate d the ALP a ctivity on da y 3 but not on days 5 and 7. On theother hand, Bioaggregate upregulated the ALP activity on day 7 but not on pre-vious d ays. Col 1 expression wa s a little diffe rent. MTA and Bioaggregateincreased the expression of Col 1 expression on days 3 and 5 and days 5 and 7,respectively (Yan et al., 2010).Zhang et al. showed that Bioaggregate and MTA can increase the activity ofALP and expression of odontoblastic differentiation genes (OC, DSPP, andDMP-1) of hDPSCs from day 1 to day 7. Only on day 7, was the ALP activity in39714.4 Nanobiomaterials in Endodontics the Bioaggregate group significantly higher than that in the MTA group. Incomparison to MTA Bioaggregate gene upregulation was higher for DSPP on day7 and for DMP-1 on days 5 and 7 (Zhang et al., 2013). These findings wereconsistent with a recent research which showed excellent cytocompatibility ofBioaggregate. In this study Cell Counting Kit-8 Assay (CCK-8) was used toassess the cell viability of hDPSCs exposed to different dilutions of Bioaggregateand MTA. The results showed that in 24 h the cell viability of the undilutedBioaggregate group was significantly higher than that of the control, dilutedBioaggregate, and diluted and undiluted MTA groups. At 48-h interval, treatingthe cells with undiluted Bioaggregate and undiluted MTA caused a significantincrease and decrease in viable cells, respectively. All dilutions of MTA reducedthe cell viability in 72 h. At 24-, 48-, and 72-h intervals, cell viability of undilutedBioaggregate was higher than that of MTA. Cell adhesion and cell migrationof undiluted Bioaggregate was also higher than that of the MTA group. It isnoteworthy that in comparison to the control group, only undiluted Bioaggregatecould enhance cell adhesion; however, cell migration was enhanced by all thedilutions of Bioaggregate and MTA. SEM images showed that Bioaggregate-treated cells were more flattened and exhibited better spreading compared toMTA-treated cells. The authors believed that hydroxyapatite formation afterhydration in Bioaggregate cement resulted in superior cytocompatibility ofBioaggregate compared to MTA. Therefore Bioaggregate coul d be considered analternative to MTA in direct pulp-capping procedures (Zhu et al., 2014).Chang et al. showed that hDPSC viability adjacent to Bioaggregate wasenhanced over time. Bioaggregate also increased ALP activity, mineralization,and mRNA expression of some odontogenic markers such as ALP, OC, dSPP,and DMP-1 in a time-dependent manner (Chang et al., 2014).Evaluation of the effect of Bioaggregate on kidney and liver showed that incomparison to the control group the amount of inflammatory cells had significantlyincreased on day 7. On this day, an increase in Kupffer cells, distortion, and dilata-tion in the hepatic portal vein (HPV) with rupture in the endothelial lining of thevein and congestion of the sinusoidal spaces were seen in the liver. In the kidney,changes in the Malpighian corpuscles of renal cortex, debris of degeneratedglomeruli, changes, and distortion in nuclei of the visceral layer of Bowman’scapsules, and vacuolation of cytoplasm of the distal convoluted tubules (DCTs)were prominent. In both kidney and liver, collagen deposition was enhanced.On day 30, inflammatory responses had significantly reduced. The kidney andliver had recovered to some extent. However, dilation of the central vein of theliver and some abnormality in hepatocytes still existed. Hemorrhage could still beseen in some areas of kidney. Collagen fibers were normal.Biochemical tests of liver and kidney also showed some changes.Bioaggregate resulted in an increase in aspartate aminotransferase (AST) level ondays 7 and 30 compared to the control group. However, the level of AST wassignificantly lower on day 30 compared to day 7. On the contrary, alanine amino-transferase (ALT) of the Bioaggregate group exhibited no differences from398 CHAPTER 14 Nanobiomaterials in endodontics the control group on day 7 but the level of ALT in the Bioaggregate groupsignificantly increased on day 30. Biochemical tests of kidney showed no dif-ferences in the serum urea levels between the Bioaggregate and control groups.However, Bioaggregate resulted in an increase in creatinine levels after 30 days.The authors concluded that Bioaggregate had some adverse effects on the kidneyand liver (Khalil and Eid, 2013).In antifungal assessment freshly mixed and 24-h set Bioaggregate could notinhibit Candida albicans growth during 1-h to 24-h periods. However, no fungalgrowth was observed after 3 and 5 days of exposu re to either preparationof Bioaggreate. Th is is probably because of a delayed increase in pH levels ofBioaggregate (Dohaithem et al., 2011).It seems the antibacterial activity of Bioaggregate is the same as MTA. Thefresh powder and powder obtained from crushing the set material of both cementscan kill more than 99% of E. faecalis cells in 1 minute and kill all the bacterialcells in 6 min. The set materials of both cement types exhibited quicker bacterialkilling activity than fresh powder. Both uncrushed cements needed more time(about 4 h) to kill all the bacteria. Surprisingly, the dentin powder did not reducethe antibacterial activity of Bioaggregate and MTA. Both cements showedinsignificant alkaline pH levels (Zhang et al., 2009).It seems that MTA is superior to Bioaggregate in acidic environments. Asmentioned earlier, of WMTA, NWMTA, and Bioaggregate, the latter has thelowest compressive strength in acidic environments (Saghiri et al., 2014).In another study the effect of acidic environment on push-out strength ofMTA and Bioaggregate as perforation repair materials was evaluated. Thesamples were stored in PBS for 4 days, in acetic acid for 4 days, in PBS for34 days, or in acetic ac id for 4 days an d in PBS for 30 days. The result sshowed that after storing in PBS for 4 days, MTA exhibited almost a twofoldgreater push-out strength value than Bioaggregate. How ever, exposing to acidicsolution for 4 days negatively affected t he dislodgment resista nce of M T A buthad no effect on resistance of Bioaggregate. On the contrary, after 34 days,acidic solution had no adverse effect on MTA but reduced the resistance ofBioaggregate. The authors concluded that MTA is more susceptible to acidicpH because of highe r ca lci um hydr oxi de con tent o f MTA com pare d toBioaggregate but this susceptibility could be reversed by exposure to PBS. Onthe other hand, Bioaggregate resiste d acid at tack better than MTA but the finaldislodging resistance of Bioaggregate was lower than MTA (Hashem andWanees Amin, 2012).Long-term use of calcium hydroxide in the apexification p rocedure ofimmature permanent teeth is associated with higher susceptibility to rootfracture. However, when Bioaggregate was used in the canal, the frac tureresistance of the teeth was about 60% higher than that of calcium hydroxide(Tuna et al., 2011).When used as a root-end filling material, Bioaggregate had less apical micro-leakage compared to amalgam, IRM, and MTA (Sayed and El Saeed, 2012).39914.4 Nanobiomaterials in Endodontics 14.4.1.2 EndoSequence Bioceramic Root Repair MaterialEndoSequence Bioceramic Root Repair Material, introduced by Brassler USA(Savannah, GA), is another bioceramic material with approximately 50% of theparticles being nanospheres with a maximum size of 1 3 103μm. These nano-particles can enter the dentinal tubules and interact with the moisture present indentin. According to the manufacturer, it is available in two specifically formulatedconsistencies: a syringable paste called EndoSequence Root Repair Material (RRM)and a condensable putty called EndoSequence Root Repair Putty (RRP) (Damaset al., 2011). It is a premixed product composed of calcium silicates, zirconiumoxide, tantalum oxide, calcium phosphate monobasic, fillers, and thickening agents.Compounds that use Ta2O5or ZrO2, such as ERRM, display more color stability anddo not have the “graying effect” seen by other Bi2O3-based root filling materials.According to the manufacturer, the material is hydrophilic, insoluble,radiopaque, and aluminum-free, with high pH and a working time of 30 min(Alanezi et al., 2010; Ma et al., 2011). This material is recommended for per-foration repair, apical surgery, apical plug, and pulp capping (Ma et al., 2011).The manufacturer claimed that complete setting occurs 12 h after contact withmoisture. However, a study byDamas et al. (2011) showed that even after 120 hof keeping in 100% humidity, none of the samples exhibited complete setting.Complete setting of materials only occurred after 168 h of storage in a moistenvironment. This is consistent with another study which showed that 48 h ormore is needed for achieving an optimum setting. Faster setting has been reportedfor ERRM putty (Charland et al., 2013; Ma et al., 2011).Cytotoxicity assay of this material has shown that two types of the material havedifferent cytotoxic effects. When the human dermal fibroblasts were treated withwhite ProRoot MTA, white Angelus MTA, Brasseler RRM, and RRP for 24 h, thethree former materials exhibited no significant differences in cell viability from thecontrol group. However, the cell survival in the RRP group was significantly lowerthan that of the control group but RRP exhibited cell survival comparable to ProRootMTA, white Angelus MTA (Damas et al., 2011).Ma et al. assessed the cytotoxicity and cell adhesion of 2- and 7-day set samplesof ERRM putty, ERRM paste, MTA, intermediate restorative material (IRM), andCavit G. The results showed that the type of the material and its setting time andincubation time significantly affected the cell survival. As an example, from day 1to day 7 the cell viability of treat ed cells decreased when the cells were treatedwith undiluted ERRM Putty, ERRM Paste, and MTA, 1:1 dilution of ERRM Pasteand all dilutions of IRM and Cavit G of 2-day set material.A high concentration of ERRM Paste was a little more toxic to cells thanERRM Putty and MTA. Seven-day set samples of RRM Putty, ERRM Paste, andMTA exhibited higher cell viability compared to their 2-day counterparts.The higher toxicity of 2-day samples of ERRM paste could be related todelayed setting of thes e materials and release of some toxic components fromunreacted material into their peripheral environment.400 CHAPTER 14 Nanobiomaterials in endodontics Precipitation of calcium carbonate was seen on the surface of ERRM pasteand ERRM putty and MTA. This is possibly the product of the reaction betweencalcium hydroxide, released from the hydration reaction of these materials, andthe CO2present in the air (Ma et al., 2011).In another study the cytotoxicity of ERRM paste was compared to that ofGrey MTA (GMTA), WMTA, and AH26. When freshly mixed materials wereevaluated the results showed that on day 1 the cell viability of the ERRM groupwith 1000 elution was higher than that of GMTA. On day 3 cell viability ofERRM was comparable to GMTA and WMTA. When the set materials weretested, cell viability of ERRM was similar to that of GMTA and WMTA in allelutions and at all times (Alanezi et al., 2010).The subcutaneous implantation of ERRM supported the in vitro findings.ERRM produced significant inflammatory responses compared to the controlgroup after 7- and 30-day intervals. However, the extent of inflammatory infiltra-tion, the amount of mononuclear cell infiltration and the thickness of fibrouscapsule around the material was significantly less in the ERRM group comparedto the MTA group on day 7.In comparison to day 7, on day 30 the thickness of fibrous capsule in both theERRM and MTA groups increas ed, but the extent of inflammatory infiltrationand the amount of mononuclear cell infiltration decreased.In conclusion it seems that MTA produced more injuries than ERRM at 7- and30-day intervals. Remarkably, the detached particles of MTA were surroundedby inflammatory cell infiltrates, necrotic areas, and abscesses, but thedetached particles of ERRM were surrounded by a fibrous capsule (Khalil andAbunasef, 2015).In antibacterial assessments against E. faecalis, ERRM paste and ERRM puttyexhibited antibacterial activity comparable to MTA (Lovato and Sedgley, 2011).The pH of freshly mixed ERRM was reported to be 12.40. When the pH ofthe surface of root filled with ERRM was measured, the pH values during the first24 h at 2- and 5-mm levels wer e around 8.5 and 9, respectively. The pH atboth levels decreased over time until it reached approximately 7.5 at week 4at both 2- and 5-mm levels. This trend was also seen in the MTA group with afinal pH of around 8 at week 4. It is noteworthy that high pH of freshly mixedWMTA remained persistent for a week but the high pH of ERRM only persistedfor the first 24 h and after that it decreased dramatically (Hansen et al., 2011).Hirschberg et al. (2013) compared the apical sealing ability of ERRM withtwo other materials. They showed that as an apical retrofill material, 93% of thesamples in the ERRM group had apical leakage with no differences from the posi-tive control group. However, only 20% of the MTA group samples exhibited api-cal leakage. No difference s were seen between the negative control and MTAgroups, contrary to the results of a study byNair et al. (2011), in which bacterialleakage test was used and no differences were shown between sealing ability ofERRM and MTA.40114.4 Nanobiomaterials in Endodontics Shokouhinejad e t al. (2014) reported that “t he marginal adaptation of thenew bioceramic material, ERRM paste/putty, was comparabl e to that of MTA.However, it might b e better to use ERRM putty or MTA in filling of the root-end cavities because of their superior adaptation compared to ERRM paste inlongitudinal sections.”In an animal study, CBCT and micro-CT images showed a significantlyhigher healing rate in teeth which were retrofilled with ERRM compared tothose retrofilled with MTA (Chen et al., 2015).In a compressive strength test ERRM soaked into either FBS or salinehad higher compressive strength than WMTA (Walsh et al., 2014). TheseauthorsalsoreportedanunusualexpansionofERRM,whichwastypicallybetween 1 and 3 mm above the upper edge of their molds. This expansion hasnot been reported by other authors. Excessive expansions could enhance therisk of root fracture.Antifungal assessment of ERRM showed that ERRM, G-MTA, and W-MTAcaused 70%, 18%, and 51% decreases in biofilm formation after 24 h of exposure.The amounts of biofilm reduction after 48 h of exposure to the tested materialwere 62%, 76%, and 77% for ERRM, G-MTA, and W-MTA, respectively. Thedifferences betwee n the control group and all the above-mentioned experimentalgroups were significant.The biofilm reduction in set ERRM sample s was significantly higher thanthose of G-MTA and W-MTA when incubated for 24 h. However, the differencewas not significant after 48 h of incubation. In samples set for 24 h, biofilmreductions after 24 h of incubation were 50% for ERRM, 24% for G-MTA, and12% for W-MTA. Biofilm reductions after 48 h of incubation were 45%, 68%,and 77% for ERRM , GMTA, and WMTA , respectively. The reduction of biofilmformation on ERRM set for 24 h was significant after 24 h when compared withboth MTA forms (50% vs. 24% and 12%, respectively). However, G-MTA andW-MTA set for the same length (24 h) reduced biofilm formation more sub-stantially after 48 h (68% and 77% vs. 45%, respectively). The authors reportedthat the average pH value of the media in contact with MTA and ERRM set for 24h was 8.5 and 8, respectively. The low pH values reported in the present studycompared with other studies might be attributed to the buffering effect of theculture medium used compared with water used previously (Alsalleeh et al., 2014).14.4.2 CALCIUM PHOSPHATE CEMENTSCalcium phosphates are commonly used in hard tissue engineering due totheir biocompatibility, osteoconductivity, and osteoinductivity (Bohner et al.,2013; Bose and Tarafder, 2012). Of all the different compositions of calciumphosphate cements, hydroxyapatite (HA; Ca5(PO4)3OH), β-tricalcium phosphate(β-TCP; Ca3(PO4)2), and biphasic calcium phosphate have been inve stigated morethan others (Bohner et al., 2013)(Table 14.2). Calcium phosphate has beenused in different areas of medical and dental sciences, in tissue engineering402 CHAPTER 14 Nanobiomaterials in endodontics Table 14.2 List of CaP Phases (Reprinted) (Bohner et al., 2013)Category Name Symbol Formula Ca/P MineralLow-temperature CaPs Monocalcium phosphate monohydrate MCPM Ca(H2PO4)2H2O 0.50 Dicalcium phosphate DCP CaHPO41.00 MonetiteDicalciumphosphate dehydrate DCPD CaHPO42H2O 1.00 BrushiteOctocalcium phosphate OCP Ca8H2(PO4)65H2O 1.33 Precipitated hydroxyapatite PHA Ca102x(HPO4)x(PO4)62x(OH)22x1.501.67 x 5 1 CDHA Ca9(HPO4)1(PO4)5(OH) 1.50x 5 0HACa10(PO4)6(OH)21.67Amorphous calcium phosphate ACP Ca3(PO4)2nH2O wheren 5 34.5; 1520% H2O1.50 High-temperature CaPs Monocalcium phosphate MCP Ca(H2PO4)20.50 α-Tricalcium phosphate α-TCP α-Ca3(PO4)21.50 β-Tricalcium phosphate β-TCP β-Ca3(PO4)21.50 Hydroxyapatite HA Ca10(PO4)6(OH)21.67 HydroxyapatiteOxyapatite OXA Ca10(PO4)6O 1.67 Tetracalcium phosphate TetCP Ca4(PO4)2O 2.00 Hilgenstockite (Samavedi et al., 2013; Shue et al., 2012), gene and drug delivery (Ito andOtsuka, 2013; Xie et al., 2013), remineralization (Cochrane et al., 2010;Khoroushi et al., 2011), and implant coating (Junker et al., 2009).The calcium and phosphate components of the material promote cell attachmentand growth in and on calcium phosphate (Choi et al., 2013). The solubility ofcalcium phosphate occurs over time, depending on the calcium/phosphate ratio,crystallinity, phase purity of the composition, and the pH of the environment (Boseand Tarafder, 2012). In contact with vital tissues such as bone surface, ions of thematerial are gradually exchanged with those in the environment; therefore, peptidesand collagen adsorb to the material and a strong bond forms between calciumphosphate and mineralized tissues (Bose and Tarafder, 2012; Choi and Ben-Nissan,2007). Even in cements with strong bonding to the mineralized tissue such as glass-ionomer cement, adding calcium phosphate to the cement improves bonding betweenglass-ionomer and mineralized tissue (Khoroushi et al., 2010; Moshaverinia et al.,2008; Nejatidanesh et al., 2012).14.4.2.1 HydroxyapatiteBlocks of HA measuring about 25 nm in width, 4 nm in thickness, and 35 nm inlength compose dentin structure up to about 70% of its weight (Cai and Tang,2008). Synthesis of nano-hydroxyapatite improved the biocompatibility, bio-activity, and mechanical properties of the material (Shi et al., 2009; Thorwarthet al., 2005) even in nano-scale size; reducing the particle size of HA from 80 to20 nm enhanced cell growth and proliferation (Sh i et al., 2009). Many researchesconsider HA as one of the best biomaterials in dentin regeneration. Combination ofHA with tricalcium phosphate has been used as a suitable scaffold for tooth ordentin regeneration by many researchers (Huang et al., 2008; Iohara et al., 2004;Tziafas et al., 2001). In the regeneration section we review the use of calciumphosphate in regenerative procedures.14.5 REGENERATIONAs previously mentioned, the regenerative procedure in endodontics is currentlyfocused on vital pulp therapy and regenerative endodontics (revascularization).Regeneration is based on three main components: stem cells, scaffolds, andgrowth factors and drugs. Although stem cell sizes cannot be reduced to nanosize,many nano-scaled scaffolds and drugs have been used in regenerative procedures.Many of these scaffolds are also loaded with drugs which are released slowly.The main goal of drug-del ivery systems is a controlled release of a particularamount of the drug (or growth factor) during a particular period of the time.In these systems, the scaffold, the drug, or both the scaffold and drug arefabricated in nanosize.404 CHAPTER 14 Nanobiomaterials in endodontics The techniq ues discussed above to induce wound-healing processes in thedental pulp are consi dered attempts to prevent tissue destruction and maintainthe vitality of the remaining pulp tissue. When the pulp has sustained severeinjuries, has mounted a severe inflammatory reaction, or has exhibited necrosis,it might be impossible to save the pulp. Pulpectomy is the treatment of choice insuch cases, and the entire root canal system must be disinfected and obturated toprevent bacterial infiltration and recontamination. Although routine root canalprocedures are generally successful, regeneration of the pulp is considered amuch superior treatment modality.It is a major challenge to treat an empty root canal with a regenerativetechnique because it resembles an alien environment for regenerative processes.Research efforts are under way to understand the cellular reactions and activitiesnecessary for regenerative processes, including formation of a scaffold, applica-tion of stem cells, and use of signaling molecules to elici t the cellular responsesfor de novo tissue development, differentiation, and revascul arization.Briefly, regenerative endodontic procedures are carried out in teeth withnecrotic pulps an d/or periapical le sions. Root canal systems of these teeth areirrigated with copious amounts of the irrigation solution for disinfection,followed by the application of triple antibiotic medication consisting o f metroni-dazole, ciprofloxacin, and tetracycline. Then, bleeding is induced in periapicaltissues so that blood fills the root canal. After a blood clot is forme d in the coro nalpart of the root canal, MTA is placed on the blood clot and a permanent restorationis applied.It might be concluded that revascularization as a result of disinfection ofthe root canal system with large amounts of irrigation solutions, applicationof triantibiotic paste, and induction of a blood clot in immature necrotic andinfected dog teeth results in accelerated revascularization and root developmentrate similar to that in imma ture vital teeth (Khademi et al., 2014).A recent study assessed various case series and reports that used revasculariza-tion based on the recommendations made by the American Association ofEndodontics. The subjects were followed for 6 108 months. Based on the resultsthere was radiographic evidence of healing in the periapi cal tissues with apicalpathoses in the majority of cases. Over 75% of cases exhibited root lengtheningalong with root canal thickening (Law, 2013).Despite the evaluation of biological responses exhibited by different dentalstem cells to nanomaterials in many studies, to the best of our knowledge nostudies to date have directly used nanomat erials in regenerative procedures.14.5.1 NANOSIZED SCAFFOLDSScaffolds are necessary to support the cells and define the ultimate structure ofthe engineered tissue (Hutmacher, 2000; Langer and Vacanti, 1993). For asuccessful pulp and dentin regeneration, the chemical composition and physical40514.5 Regeneration structure of scaffolds should mimic the features of the extracellular matrix,extracellular fibers, and proteins of the pulp and dentin (Ekblom et al., 1986;Ma, 2008). Collagen, as a main organic component of the dentin, is asuitable natural scaffold for pulp and dentin regeneration (Prescott et al., 2008).On the other hand, synthetic scaffolds have attracted great attention due to theirgreat control on the biodegradation rate, mechanical and physical properties, andpattern and structure. Many efforts have been made for fabricating nanosizedscaffold to mimic the structure of extracellular matrix. Three methods have beenused to produce nano-fibrous scaffolds: electrospinning, self-assembly, and phaseseparation (Smith et al., 2009).14.5.1.1 Methods of fabricationIn electrospinning, an electric charge is used to flow polymer solution from anorifice to a collector (Smith and Ma, 2004). By controlling different factorssuch as nozzlecollector distance, radius of initial jet, charge de ns ity, viscosity,and relaxation time the fiber diameter can be determined (Thompson et al.,2007). Nano-fibrous scaffolds of polycaprolactone (Li et al., 2003), polylacticacid (Yang et al., 2005) poly(D,L-lactid e)-poly (ethy lene glyc ol) (PLA-PEG)(Luu et al., 2003), silk (Li et al., 2006), and collagen have been ge nera ted w iththis method (Figures 14.114. 6).Electrospinning technique is more suitable for the fabrication of two-layerstructures. However, three-dimensional scaffolds produced by electrospinningcombined with multilayer technique resulted in a sufficient volume for cellattachment and cell penetration in regeneration processes (Srouji et al., 2008).FIGURE 14.1SEM image of the electrospun nanofibers of polyvinyl alcohol, gelatin, and bioactive glass.406 CHAPTER 14 Nanobiomaterials in endodontics The principle of self-assembly forms a pattern or a structure by the autonomousinteraction between different biomolecules or components, such as phospholipidsthat form cell membranes (Ma, 2008; Smith et al., 2009). Peptide-amphiphilenanofibers (Hartgerink et al., 2001) and chitin (Rolandi and Rolandi, 2014)structures were fabricated with this technique. However, this method is rela-tively new and limited studies have used this technique in tissue engineering(Vasita and Katti, 2006).FIGURE 14.3SEM image of the electrospun nanofibers of polycaprolactone, gelatin, and bioactive glass.FIGURE 14.2SEM image of the electrospun nanofibers of polycaprolactone, bioactive glass containing Cu.40714.5 Regeneration In phase separation, a polymer solution, usually with thermal treatment, isseparated into two polymer-rich and polymer-poor phases. After a five-stepprocessing a foam-like nanoscaffold is fabricated (Ma, 2008; Smith et al., 2009).There are many advantages to this method. Phase separation does not needadvanced equipment; it is a relatively simple procedure and there are a lot ofcontrols on the size, shape, and porosity of the structure (Ma and Zhang, 1999).FIGURE 14.5SEM image of osteoblast growth on cellulose nanofibers reinforced with starch.FIGURE 14.4SEM image of the electrospun nanofibers of PLGA and zeolite.408 CHAPTER 14 Nanobiomaterials in endodontics 14.5.1.2 Antibiotic-releasing scaffoldsAs mentioned earlier a mixture of equal amounts of minocycline, ciprofloxacin, andmetronidazole, known as triple antibiotic paste (TAP), is commonly used for rootcanal disinfection in regenerative endodontics (Hoshino et al., 1996; Huang, 2008;Khademi et al., 2014; Sato et al., 1996). This mixture is very effective in eliminatinga broad spectrum of bacteria. However, triple antibiotic paste is cytotoxic to DPSCsand SCAPs in a time- and concentration-dependent manner (Chuensombat et al.,2013). Use of drug-releasing scaffolds is a suggested approach for slow and con-trolled release of antibiotics to the root canal system with less cytotoxic effects thanthe paste or solution forms. These scaffolds are degraded in the canal and slowlyrelease the antibiotic mixture into the surrounding environment. The first antibiotic-containing nanofibers for regenerative endodontics were introduced in 2013 byBottino et al. (2013). The scaffold was made from polydioxanone monofilamentsuture material (PDS II®, Ethicon, Somerville, NJ, USA) containing 5 or 25% ofciprofloxacin or metronidazole antibiotics, using an electrospinning technique.Handling and mechanical properties of PDS make it a suitable choice for use in theroot canal system. The results of this study showed that the amounts of drug releasedduring the first 48 h were 22.4% and 27.52% for 5% and 25% ciprofloxacin and51.4% and 44.6% for 5% and 25% metronidazole, respectively. In almost all theFIGURE 14.6SEM image of polyhydroxybutyratefolic acid nanoparticles.40914.5 Regeneration groups a plateau drug release was observed after an initial burst during the first 8 h.In antibacterial tests, ciprofloxacin at both 5% and 25% concentrations was effectiveagainst E. faecalis and Porphyromonas gingivalis. Metronidazole did not show anyinhibitory effect on E. faecalis but it was effective against P. gingivalis at both doses.With the exception of 25% ciprofloxacin, none of the antibiotics had cytotoxiceffects on DPSCs (Bottino et al., 2013).In another study, a different proportion of metronidazole and ciprofloxacin wasincorporated into the PDS nanofibers (Palasuk et al., 2014). The 1:1 metronidazole/ciprofloxacin proportion exhibited the highest tensile strength when compared to3:1 (metronidazole/ciprofloxacin), 1:3 (metronidazole/ciprofloxacin), metronida-zole only, ciprofloxacin only, and scaffold only. With the exception of themetronidazole-only group, all the antibiotic-containing scaffolds had inhibitoryeffects against E. faecalis, P. gingivalis, and F. nucleatum. Contrary to the previousstudy, metronidazole was not effective against P. gingivalis and no difference wasobserved between 5% and 25% concentrations of ciprofloxacin. In cell assessment,scaffolds showed no toxicity or showed slight toxicity, suggesting them as an alter-native to the antibiotic paste in regenerative endodontics (Palasuk et al., 2014).A PDS-containing triantibiotic mixture also had promising inhibitory effects onActinomyces naeslundii, a Gram-positive anaerobic bacterial species which is themost commonly isolated bacteria from traumatized immature teeth with necroticpulps. TAP scaffold had a lower antibacterial activity than TAP solution, but stillhigher than the control group. Interestingly, metronidazole and ciprofloxacin hadan initial burst release during the first 24 h, followed by a constant and sustainedrelease up to 30 days. Minocycline first exhibited an initial burst; however, itsrelease dramatically reduced within 15 days with no further release after this time(Albuquerque et al., 2015a).The effect of PDS electrospun scaffold containing 5% or 25% ciprofloxacin onthe E. faecalis biofilm on dentin slices also showed dose-dependent effectivenessof both antibiotic concentrations in inhibition of bacterial growth (Albuquerqueet al., 2015b).14.5.1.3 Nanoscaffolds in regenerative endodonticsThe similarity in structure of nanofibers and extracellular matrix facilitates tissueformation.Researchers have shown that nanofibrous poly(l-lactic) acid scaffolds fabricatedwith phase separation technique mimic the structure of collagen I. Dental pulpstem cells (DPSCs) also exhibited better attachment, growth, and odontogenic dif-ferentiation on the NF scaffolds compared to non-nanofibrous ones (Wang et al.,2011). Adding BMP-7 and dexamethasone to the PLLA nanofibers promoted theodontogenic differentiation of DPSCs seeded on this scaffold (Wang et al., 2010).The inductive effect of the electrospun PCLs has been shown in directpulp-capping procedures. Direct pulp capping (DPC) is one of the mainstreams ofpulp regeneration (Garcia-Godoy and Murray, 2012) and for the past 60 yearscalcium hydroxide has been traditionally used for DPCs. Ca(OH)2can increase410 CHAPTER 14 Nanobiomaterials in endodontics recruitment, migration, proliferation, and mineralization of both DPSCs andPDLSCs (Ji et al., 2010); however, the long-term success rate of teeth cappedwith calcium hydroxide is about 60%. Mineral trioxide aggregate (MTA) hasbeen shown to be more suitable for DPC procedures, with a success rate over80% shown in long-term clinical trials (Hilton et al., 2013; Mente et al., 2014).Tooth discoloration and cytotoxicity of fre shly mixed MTA are some of itsdrawbacks (Balto, 2004; Belobrov and Parashos, 2011).To overcome these disadvantages use of an electrospun nanofiber mesh ofPCL has been recommended. Studies have shown that PCL n anofibers canenhance the bioactivity of MTA in DPC treatments (Lee et al., 2015, 2012). In ananimal study, either MTA or two layers of PCL mesh and MTA were placed onthe exposed pulp of premolars in beagle dogs. The histologic evaluation ofsectioned teeth showed that the dentin bridge formed beneath PCL/MTA was fourtimes thicker and more organized than that of MTA. In the PCL/MTA group, lesstertiary dentin precipitated on the pre-existing dentin in the pulp chamber. In cellculture evaluation, MTA show ed more cell toxicity and less cell proliferationcompared to PCL/MTA. These results show that PCL/MTA is a more favorablecombination for the pulp-capping procedure than MTA (Lee et al., 2012).A clinical study supported the results of the above-mentioned study. In this study,60 teeth exposed due to trauma or caries were capped with either MTA orPCL/MTA. In a 3-month follow-up, radiographic evaluations showed thatPCL/MTA induced a thicker dent in formation in shorter time compared to MTA.It seems that PCL mesh can reduce the cytotoxicity of MTA, resu lting in morecell survival and consequently faster cell attachment, proliferation, andodontoblastic differ entiation. In addition, during the 3 months of the trial, due toshallow penetration of MTA byproducts into dentinal tubules, less tooth dis-coloration was seen in the PCL/MTA group than the MTA group (Lee et al., 2015).Nowadays CS NPs, too, have attracted great attention as a drug-delivery vehicle,especially for proteins and genes. Drug release from CS NPs occurs with one ormore of three different mechanisms: (1) release from the surface of particles;(2) drug diffusion through the matrix of the carrier; and (3) erosion or degradation ofthe carrier (Gan and Wang, 2007; Soppimath et al., 2001; Zhou et al., 2013b). Itseems the mechanism of drug release from the particle has a considerable effect onthe adjacent cells. In a recent study, bovine serum albumin was loaded on CS NPswith two different techniques: the encapsulation technique in which the desired drugor protein was embedded in the matrix of the carrier and the adsorption technique inwhich the drug or protein only adsorbs to the surface of the carrier. Stem cells fromthe apical papilla (SCAP) were treated with the two above-mentioned nanoparticlesfor 28 days and the alkaline phosphatase activity of the two groups was measuredevery 7 days. Comparison of groups showed no significant differences in the ALPactivity for 7 and 14 days; however, at 21 and 28 days, higher ALP activity wasseen with the encapsulation technique compared to the adsorption technique(Shrestha et al., 2014). The same authors investigated the response of SCAPs todexamethasone-loaded CS NPs fabricated by encapsulation or adsorption technique.41114.5 Regeneration Contrary to the previous study, the SCAPs exhibited higher ALP activity in theadsorption group compared to the encapsulation group. Although same amount ofdexamethasone was loaded in both groups, the adsorption group released higher con-centrations of dexamethasone compared to the encapsulation group. Dentin matrixphosphoprotein-1 (DMP-1) and DSPP gene expressions were higher in CS NPs withdexamethasone than CS NPs without dexamethasone. In fact, dexamethasonereleased from CS NPs enhanced odontogenic differentiation of SCAPs (Shresthaet al., 2015b).14.5.2 NANOPARTICLES IN REGENERATIVE ENDODONTICS14.5.2.1 Bioactive glass in regenerative endodonticsWe previously discussed the antibacterial effect of BG NPs. BG is alsoextensively used in tissue engineering and regeneration procedures.In endodontics, when the effect of nano-58S BG, 58S BG, or 45S5 BG on thedifferentiation of DPSC s was evaluated, the results showed that nano-58S BGupregulated expression of ALP, DMP1, Col 1, and DSPP, compared to 58S BGor 45S5 BG. All BGs induced odontoblastic differentiation of DPSCs and nano-58S BG was the most effective. In addition, nano-58S BG exhibited a higherrelease of calcium than other BGs. Therefore, when compared to regular forms,the nano-form of BG is more potent in inducing differentiation and mineralizationin DPSC (Gong et al., 2014).Since BG has high brittleness and low tensile strength, it has been recommendedin a biopolymer composition with collagen to achieve suitable properties for dentaltissue engineering (Bae et al., 2012). This biopolymer can upregulate the odonto-genic differentiation of DPSCs by an ionic-mediated process (Bae et al., 2012). Theionic component released from BG NPs, too, can enhance cementoblast viability andproliferation (Carvalho et al., 2012). This means BG NPs can be used in regenerationof cementum and periodontal ligament in cases such as traumatic injuries or possiblyin some types of root resorption cases.14.5.2.2 Calcium phosphates in regenerative proceduresCalcium phosphate, especially hydroxyapatite, is used in different areas of dentalscience, especially in tooth regeneration.In an animal study, nanosized HA paste was used as a pulp dressing materialeither in pulpotomy or direct pulp-capping treatments of primary teeth of pigs.No sign of moderate or severe inflammation was seen and hard tissue was formedin both pulpotomy and DPC groups (Shayegan et al., 2010).In a study, the effect of DPSC s on the gelatin/polycaprolactone scaffold withand without HA NPs was evaluated. Blending gelatin with polycaprolactone(PCL) resulted in a scaffold with high biocompatibility potential and improvedmechanical and chemical properties. It was supposed that adding HA NPs to thescaffold could enhance cell adhesion and cell differentiation. The results show ed412 CHAPTER 14 Nanobiomaterials in endodontics that DPSC attached to both scaffolds similarly and the added HA NPs did notimprove cell attachment and growth. However, HA NPs effectively enhanc edexpression of osteoclacin, bone sialoprotein, DSPP, and DMP1 gene compared toplain scaffold, which showed the positive effect of HA NPs on differentiation ofDPSCs but not on their attachment (Yang et al., 2010).Using a chelator is another approach to enhance the attachment of HA NPs tothe root surface. EDTA, citric acid, EDTAC, etc., have been used to remove thesmear layer and improve the bond of obturation material or other cements tothe root structure (Ebrahimi Dastgurdi et al., 2013; Zare Jahromi et al., 2010).The results of a recent study showed preconditioning the root surface with 24%EDTA can improve the retention of HA NPs (Gamal and Iacono, 2013).Calcium phosphate NPs have attracted great attention as drug-deliverysystems. They can be used for releasing antibacterial agents, growth factors, orother therapeutic agents (Uskokovi´c and Uskokovi´c, 2011).Yang et al. (2008) used calcium phosphate NPs as gene vectors for transfectingbone morphogenetic protein 2 into the rat dental pulp stem cells. They collectedSTRO-1 1 DPSCs due to their higher potential for odontogenic differentiation.These cells were transfected with nanoparticles of calcium phosphate, encapsulat-ing plasmid deoxyribonucleic acid (DNA) (plasmid enhanced green fluorescentprotein-BMP2). The results showed that transfected DPSCs had a higher alkalinephosphatase activity and higher expression of odontogenic markers such as dentinsialophosphoprotein and osteocalcin compared to non-transfected cells. Theauthors concluded that calcium phosphate nanoparticles can successfully be usedas gene vectors with relatively superior properties compared to other vectors.14.6 CONCLUSIONSIn recent years new concepts and aspects have emerged in endodontic treatment.Regenerative endodontics, stem cells in endodontics, new instruments, and definitelynanomaterials and nanobiomaterials are going to change the future of endodontictreatments. In this chapter we tried to review the nanomaterials in different area ofendodontics. Many studies have shown the superiority of nanomaterials comparedto larger-size materials. However, there are still some concerns about patient andoperator safety in clinical applications, necessitating further investigations.In addition, there are many new areas in endodon tics where nanotechnologycould be helpful. There are hopes that novel dental endodontic materials withnanoparticles incorporated will be available in near future.ACKNOWLEDGMENTSWe express our special thanks to Professor Mohammad Rafienia for providing the originalphotos.413Acknowledgments REFERENCESAbramovitz, I., Beyth, N., Weinberg, G., Borenstein, A., Polak, D., Kesler-Shvero, D.,et al., 2012. In vitro biocompatibility of endodontic sealers incorporating antibacterialnanoparticles. J. Nanomater. 2012, 12.Alanezi, A.Z., Jiang, J., Safavi, K.E., Spangberg, L.S.W., Zhu, Q., 2010. Cytotoxicityevaluation of endosequence root repair material. Oral Surg. Oral Med. Oral Pathol.Oral Radiol. Endod. 109, e122e125. Available from:http://dx.doi.org/10.1016/j.tripleo.2009.11.028.Albuquerque, M.T.P., Ryan, S.J., Mu¨nchow, E.A., Kamocka, M.M., Gregory, R.L., Valera,M.C., et al., 2015a. Antimicrobial effects of novel triple antibiotic paste-mimicscaffolds on actinomyces naeslundii biofilm. J. Endod. 41 (8), 13371343. Availablefrom:http://dx.doi.org/10.1016/j.joen.2015.03.005.Albuquerque, M.T.P., Valera, M.C., Moreira, C.S., Bresciani, E., de Melo, R.M., Bottino, M.C.,2015b. Effects of ciprofloxacin-containing scaffolds on Enterococcus faecalis biofilms.J. Endod. 41, 710714. Available from:http://dx.doi.org/10.1016/j.joen.2014.12.025.Al-Daafas, A., Al-Nazhan, S., 2007. Histological evaluation of contaminated furcal perfo-ration in dogs’ teeth repaired by MTA with or without internal matrix. Oral Surg. OralMed. Oral Pathol. Oral Radiol. Endod. 103, e92e99. Available from:http://dx.doi.org/10.1016/j.tripleo.2006.09.007.Alsalleeh, F., Chung, N., Stephenson, L., 2014. Antifungal activity of endosequence rootrepair material and mineral trioxide aggregate. J. Endod. 40, 18151819. Availablefrom:http://dx.doi.org/10.1016/j.joen.2014.08.002.Andreasen, J.O., Farik, B., Munksgaard, E.C., 2002. Long-term calcium hydroxide as aroot canal dressing may increase risk of root fracture. Dent. Traumatol. Off. Publ. Int.Assoc. Dent. Traumatol. 18, 134137.Asgary, S., Eghbal, M.J., Ehsani, S., 2010. Periradicular regeneration after endodonticsurgery with calcium-enriched mixture cement in dogs. J. Endod. 36, 837841.Available from:http://dx.doi.org/10.1016/j.joen.2010.03.005.Bae, W.-J., Min, K.-S., Kim, J.-J., Kim, J.-J., Kim, H.-W., Kim, E.-C., 2012.Odontogenic responses of human dental pulp cells to collagen/na nobioactive glassnanocomposites. Dent. Mater. 28, 12711279. Available from:http://dx.doi.org/10.1016/j.dental.2012.09.011.Balto, H .A., 2004. Atta chme nt and morphological behavior of human periodontalligament fibroblasts to mineral trioxide aggregate: a scanning electron microscopestudy. J. Endod. 30, 2529. Available from:http://dx.doi.org/10.1097/00004770-200401000-00005.Banchs, F., Trope, M., 2004. Revascularization of immature permanent teeth with apicalperiodontitis: new treatment protocol? J. Endod. 30, 196200. Available from:http://dx.doi.org/10.1097/00004770-200404000-00003.Barros, J., Costa-Rodrigues, J., Lopes, M.A., Pina-Vaz, I., Fernandes, M.H., 2014a.Response of human osteoblastic and osteoclastic cells to AH plus and pulp canal sealercontaining quaternary ammonium polyethylenimine nanoparticles. J. Endod. 40,11491155. Available from:http://dx.doi.org/10.1016/j.joen.2014.03.022.Barros, J., Silva, M.G., Roˆc¸as, I.N., Gonc¸alves, L.S., Alves, F.F., Lopes, M.A., et al.,2014b. Antibiofilm effects of endodontic sealers containing quaternary ammoniumpolyethylenimine nanoparticles. J. Endod. 40, 11671171.414 CHAPTER 14 Nanobiomaterials in endodontics Barros, J., Silva, M.G., Rodrigues, M.A., Alves, F.R.F., Lopes, M.A., Pina-Vaz, I., et al.,2014c. Antibacterial, physicochemical and mechanical properties of endodontic sealerscontaining quaternary ammonium polyethylenimine nanoparticles. Int. Endod. J. 47,725734. Available from:http://dx.doi.org/10.1111/iej.12207.Belobrov, I., Parashos, P., 2011. Treatment of tooth discoloration after the use of whitemineral trioxide aggregate. J. Endod. 37, 10171020. Available from:http://dx.doi.org/10.1016/j.joen.2011.04.003.Bohner, M., Tadier, S., van Garderen, N., de Gasparo, A., Do¨belin, N., Baroud, G., 2013.Synthesis of spherical calcium phosphate particles for dental and orthopedicapplications. Biomatter, 3. Available from:http://dx.doi.org/10.4161/biom.25103.Bose, S., Tarafder, S., 2012. Calcium phosphate ceramic systems in growth factor and drugdelivery for bone tissue engineering: a review. Acta Biomater. 8, 14011421.Available from:http://dx.doi.org/10.1016/j.actbio.2011.11.017.Bottino, M.C., Kamocki, K., Yassen, G.H., Platt, J.A., Vail, M.M., Ehrlich, Y., et al., 2013.Bioactive nanofibrous scaffolds for regenerative endodontics. J. Dent. Res. 92,963969. Available from:http://dx.doi.org/10.1177/0022034513505770.Cai, Y., Tang, R., 2008. Calcium phosphate nanoparticles in biomineralization andbiomaterials. J. Mater. Chem. 18, 37753787.Camilleri, J., 2007. Hydration mechanisms of mineral trioxide aggregate. Int. Endod. J. 40,462470. Available from:http://dx.doi.org/10.1111/j.1365-2591.2007.01248.x.Carvalho, S.M., Oliveira, A.A.R., Jardim, C.A., Melo, C.B.S., Gomes, D.A., de Fa´timaLeite, M., et al., 2012. Characterization and induction of cementoblast cell proliferationby bioactive glass nanoparticles. J. Tissue Eng. Regen. Med. 6, 813821. Availablefrom:http://dx.doi.org/10.1002/term.488.Chang, S.-W., Lee, S.-Y., Kum, K.-Y., Kim, E.-C., 2014. Effects of ProRoot MTA,Bioaggregate, and Micromega MTA on odontoblastic differentiation in human dentalpul p cells. J. E ndod. 40, 11 3118. Available from :http://dx.doi.org/10.1016/j.joen.2013.09.036.Charland, T., Hartwell, G.R., Hirschberg, C., Patel, R., 2013. An evaluation of setting timeof mineral trioxide aggregate and endosequence root repair material in the presence ofhuman blood and minimal essential media. J. Endod. 39, 10711072. Available from:http://dx.doi.org/10.1016/j.joen.2013.04.041.Chen,I.,Karabucak,B.,Wang,C.,Wang,H.-G.,Koyama,E.,Kohli,M.R.,etal.,2015. Healing after root-end microsurgery by using mineral trioxide aggregate anda new calcium silicatebased bioceramic material as root-end filling materials indogs. J. Endod. 41, 38 9399. Available from:http://dx.doi.org/10.1 016/j.jo en.2014.11.005.Choi, A.H., Ben-Nissan, B., 2007. Sol-gel production of bioactive nanocoatings for medicalapplications. Part II: current research and development. Nanomed. 2, 5161. Availablefrom:http://dx.doi.org/10.2217/17435889.2.1.51.Choi, A.H., Ben-Nissan, B., Matinlinna, J.P., Conway, R.C., 2013. Current perspectives:calcium phosphate nanocoatings and nanocomposite coatings in dentistry. J. Dent. Res.92, 853859. Available from:http://dx.doi.org/10.1177/0022034513497754.Chuensombat, S., Khemaleelakul, S., Chattipakorn, S., Srisuwan, T., 2013.Cytotoxic effects and antibacterial efficacy of a 3-antibiotic combination: an in vitrostudy. J. Endod. 39, 81 3819. Availabl e from:http://dx.doi.org/10.1016/j.joen.2012.11.041.415References Cochrane, N.J., Cai, F., Huq, N.L., Burrow, M.F., Reynolds, E.C., 2010. New approachesto enhanced remineralization of tooth enamel. J. Dent. Res. 89, 11871197. Availablefrom:http://dx.doi.org/10.1177/0022034510376046.Coomaraswamy, K.S., Lumley, P.J., Hofmann, M.P., 2007. Effect of bismuth oxideradioopacifier content on the material properties of an endodontic portland cement-based(MTA-like) system. J. Endod. 33, 295298. Available from:http://dx.doi.org/10.1016/j.joen.2006.11.018.Damas, B.A., Wheater, M.A., Bringas, J.S., Hoen, M.M., 2011. Cytotoxicity comparison ofmineral trioxide aggregates and endosequence bioceramic root repair materials.J. Endod. 37, 372375. Available from:http://dx.doi.org/10.1016/j.joen.2010.11.027.Darvell, B.W., Wu, R.C.T., 2011. “MTA”—an hydraulic silicate cement: review updateand setting reaction. Dent. Mater. 27, 407422. Available from:http://dx.doi.org/10.1016/j.dental.2011.02.001.De-Deus, G., Canabarro, A., Alves, G., Linhares, A., Senne, M.I., Granjeiro, J.M., 2009.Optimal cytocompatibility of a bioceramic nanoparticulate cement in primary humanmesenchymal cells. J. Endod. 35, 13871390. Available from:http://dx.doi.org/10.1016/j.joen.2009.06.022.Del Carpio-Perochena, A., Kishen, A., Shrestha, A., Bramante, C.M., 2015. AntibacterialProperties Associated with Chitosan Nanoparticle Treatment on Root Dentin and 2 Types ofEndodontic Sealers. J. Endod. 41, 13531358. Available from:http://dx.doi.org/10.1016/j.joen.2015.03.020.Dianat, O., Azadnia, S., Mozayeni, M.A., 2015a. Toxicity of calcium hydroxidenanoparticles on murine fibroblast cell line. Iran Endod. J. 10, 4954.Dianat, O., Saedi, S., Kazem, M., Alam, M., 2015b. Antimicrobial activity of nanoparticle cal-cium hydroxide against Enterococcus faecalis:anin vitro study. Iran Endod. J. 10, 3943.Dohaithem, A., Al-Nasser, A., Al-Badah, A., Al-Nazhan, S., Al-Maflehi, N., 2011. Anin vitro evaluation of antifungal activity of bioaggregate. Oral Surg. Oral Med. OralPathol. Oral Radiol. Endod. 112, e27e30. Available from:http://dx.doi.org/10.1016/j.tripleo.2011.03.037.Dominguez, M., Witherspoon, D., Gutmann, J., Opperman, L., 2003. Histological andscanning electron microscopy assessment of various vital pulp-therapy materials. J. Endod.29, 324333. Available from:http://dx.doi.org/10.1097/00004770-200305000-00003.Ebrahimi Dastgurdi, M., Khabiri, M., Khademi, A., Zare Jahromi, M., Hosseini Dastnaei,P., 2013. Effect of post length and type of luting agent on the dislodging time ofmetallic prefabricated posts by using ultrasonic vibration. J. Endod. 39, 14231427.Available from:http://dx.doi.org/10.1016/j.joen.2013.07.005.Ekblom, P., Vestweber, D., Kemler, R., 1986. Cell-matrix interactions and cell adhesionduring development. Annu. Rev. Cell Biol. 2, 2747. Available from:http://dx.doi.org/10.1146/annurev.cb.02.110186.000331.Gamal, A.Y., Iacono, V.J., 2013. Mixed nano/micro-sized calcium phosphate compositeand EDTA root surface etching improve availability of graft material in intrabonydefects: an in vivo scanning electron microscopy evaluation. J. Periodontol. 84,17301739. Available from:http://dx.doi.org/10.1902/jop.2013.120701.Gan, Q., Wang, T., 2007. Chitosan nanoparticle as protein delivery carrier—systematic exami-nation of fabrication conditions for efficient loading and release. Colloids Surf. BBiointerfaces 59, 2434. Available from:http://dx.doi.org/10.1016/j.colsurfb.2007.04.009.416 CHAPTER 14 Nanobiomaterials in endodontics Garcı´a-Contreras, R., Argueta-Figueroa, L., Mejı´a-Rubalcava, C., Jime´nez-Martı´nez, R.,Cuevas-Guajardo, S., Sa´nchez-Reyna, P.A., et al., 2011. Perspectives for the use ofsilver nanoparticles in dental practice. Int. Dent. J. 61, 297301. Available from:http://dx.doi.org/10.1111/j.1875-595X.2011.00072.x.Garcia-Godoy, F., Murray, P.E., 2012. Recommendations for using regenerative endodonticprocedures in permanent immature traumatized teeth. Dent. Traumatol. Off. Publ. Int.Assoc. Dent. Traumatol. 28, 3341. Available from:http://dx.doi.org/10.1111/j.1600-9657.2011.01044.x.Ghasemi, N., Rahimi, S., Lotfi, M., Solaimanirad, J., Shahi, S., Shafaie, H., et al., 2014.Effect of mineral trioxide aggregate, calcium-enriched mixture cement and mineraltrioxide aggregate with disodium hydrogen phosphate on BMP-2 production. Iran.Endod. J. 9, 220224.Gomes-Filho, J.E., Silva, F.O., Watanabe, S., Angelo Cintra, L.T., Tendoro, K.V., Dalto,L.G., et al., 2010. Tissue reaction to silver nanoparticles dispersion as an alternativeirrigating solution. J. Endod. 36, 16981702. Available from:http://dx.doi.org/10.1016/j.joen.2010.07.007.Gong, W., Huang, Z., Dong, Y., Gan, Y., Li, S., Gao, X., et al., 2014. Ionic extraction of anovel nano-sized bioactive glass enhances differentiation and mineralization of humandental pulp cells. J. Endod. 40, 8388. Available from:http://dx.doi.org/10.1016/j.joen.2013.08.018.Grech, L., Mallia, B., Camilleri, J., 2013. Characterization of set Intermediate RestorativeMaterial, Biodentine, Bioaggregate and a prototype calcium silicate cement for use asroot-end filling materials. Int. Endod. J. 46, 632641. Available from:http://dx.doi.org/10.1111/iej.12039.Hansen, S.W., Marshall, J.G., Sedgley, C.M., 2011. Comparison of intracanal endosequenceroot repair material and ProRoot MTA to induce ph changes in simulated root resorptiondefects over 4 weeks in matched pairs of human teeth. J. Endod. 37, 502506. Availablefrom:http://dx.doi.org/10.1016/j.joen.2011.01.010.Hartgerink, J.D., Beniash, E., Stupp, S.I., 2001. Self-assembly and mineralization ofpeptide-amphiphile nanofibers. Science 294, 1684 1688. Available from:http://dx.doi.org/10.1126/science.1063187.Hashem, A.A.R., Wanees Amin, S.A., 2012. The effect of acidity on dislodgment resistanceof mineral trioxide aggregate and Bioaggregate in furcation perforations: an in vitrocomparative study. J. Endod. 38, 245249. Available from:http://dx.doi.org/10.1016/j.joen.2011.09.013.Hilton, T.J., Ferracane, J.L., Mancl, L., 2013. Comparison of CaOH with MTA for directpulp capping. J. Dent. Res. 92, S16S22. Available from:http://dx.doi.org/10.1177/0022034513484336.Hirschberg, C.S., Patel, N.S., Patel, L.M., Kadouri, D.E., Hartwell, G.R., 2013.Comparison of sealing ability of MTA and endosequence bioceramic root repairmaterial: a bacte rial leakage study. Quintessence Int. Ber l. Ger 1985 (44),e157e162.Hoshino, E., Kurihara-Ando, N., Sato, I., Uematsu, H., Sato, M., Kota, K., et al., 1996.In-vitro antibacterial susceptibility of bacteria taken from infected root dentine to amixture of ciprofloxacin, metronidazole and minocycline. Int. Endod. J. 29, 125 130.Available from:http://dx.doi.org/10.1111/j.1365-2591.1996.tb01173.x.417References Huang, G.T.-J., 2008. A paradigm shift in endodontic management of immature teeth:conservation of stem cells for regeneration. J. Dent. 36, 379386. Available from:http://dx.doi.org/10.1016/j.jdent.2008.03.002.Huang, G.T.-J., Sonoyama, W., Liu, Y., Liu, H., Wang, S., Shi, S., 2008. The hiddentreasure in apical papilla: the potential role in pulp/dentin regeneration and biorootengineering. J. Endod. 34, 645651. Available from:http://dx.doi.org/10.1016/j.joen.2008.03.001.Hutmacher, D.W., 2000. Scaffolds in tissue engineering bone and cartilage. Biomaterials21, 25292543.Iohara, K., Nakashima, M., Ito, M., Ishikawa, M., Nakasima, A., Akamine, A., 2004.Dentin regeneration by dental pulp stem cell therapy with recombinant human bonemorphogenetic protein 2. J. Dent. Res. 83, 590595.Ito, T., Otsuka, M., 2013. Application of calcium phosphate as a controlled-release device.Biol. Pharm. Bull. 36, 16761682.Javidi, M., Afkhami, F., Zarei, M., Ghazvini, K., Rajabi, O., 2014. Efficacy of a combinednanoparticulate/calcium hydroxide root canal medication on elimination ofEnterococcus faecalis. Aust. Endod. J. 40, 6165. Available from:http://dx.doi.org/10.1111/aej.12028.Ji, Y.-M., Jeon, S.H., Park, J.-Y., Chung, J.-H., Choung, Y.-H., Choung, P.-H., 2010.Dental stem cell therapy with calcium hydroxide in dental pulp capping. Tissue Eng.Part A 16, 1823 1833. Available from:http://dx.doi.org/10.1089/ten.TEA.2009.0054.Junker, R., Dimakis, A., Thoneick, M., Jansen, J.A., 2009. Effects of implant surface coatingsand composition on bone integration: a systematic review. Clin. Oral Implants Res. 20(Suppl. 4), 185206. Available from:http://dx.doi.org/10.1111/j.1600-0501.2009.01777.x.Kesler Shvero, D., Abramovitz, I., Zaltsman, N., Perez Davidi, M., Weiss, E.I., Beyth,N., 2013. Towards antibacterial endodontic sealers using quaternary ammoniumnanoparticles. Int. Endod. J. 46, 747754. Available from:http://dx.doi.org/10.1111/iej.12054.Khademi, A.A., Dianat, O., Mahjour, F., Razavi, S.M., Younessian, F., 2014. Outcomes ofrevascularization treatment in immature dog’s teeth. Dent. Traumatol. Off. Publ. Int. Assoc.Dent. Traumatol. 30, 374379. Available from:http://dx.doi.org/10.1111/edt.12100.Khalil, W.A., Abunasef, S.K., 2015. Can mineral trioxide aggregate and nanoparticulateendosequence root repair material produce injurious effects to rat subcutaneous tissues?J. Endod. 41, 11511156. Available from:http://dx.doi.org/10.1016/j.joen.2015.02.034.Khalil, W.A., Eid, N.F., 2013. Biocompatibility of BioAggregate and mineral trioxideaggregate on the liver and kidney. Int. Endod. J. 46, 730737. Available from:http://dx.doi.org/10.1111/iej.12050.Khoroushi, M., Feiz, A., Khodamoradi, R., 2010. Fracture resistance of endodontically-treated teeth: effect of combination bleaching and an antioxidant. Oper. Dent. 35,530537. Available from:http://dx.doi.org/10.2341/10-047-L.Khoroushi, M., Keshani, F., 2013. A review of glass-ionomers: from conventionalglass-ionomer to bioactive glass-ionomer. Dent. Res. J 10, 411420.Khoroushi, M., Mazaheri, H., Manoochehri, A., 2011. Effect of CPP-ACP application onflexural strength of bleached enamel and dentin complex. Oper. Dent. 36, 372379.Available from:http://dx.doi.org/10.2341/10-280-L.Kishen, A., 2010. Advanced therapeutic options for endodontic biofilms. Endod. Top. 22,99123. Available from:http://dx.doi.org/10.1111/j.1601-1546.2012.00284.x.418 CHAPTER 14 Nanobiomaterials in endodontics Kishen, A., Shi, Z., Shrestha, A., Neoh, K.G., 2008. An investigation on the antibacterialand antibiofilm efficacy of cationic nanoparticulates for root canal disinfection.J. Endod. 34, 15151520. Available from:http://dx.doi.org/10.1016/j.joen.2008.08.035.Komabayashi, T., Spa˚ngberg, L.S.W., 2008a. Comparative analysis of the particle size andshape of commercially available mineral trioxide aggregates and portland cement: astudy with a flow particle image analyzer. J. Endod. 34, 9498. Available from:http://dx.doi.org/10.1016/j.joen.2007.10.013.Komabayashi, T., Spa˚ngberg, L.S.W., 2008b. Particle size and shape analysis of mta finerfractions using portland cement. J. Endod. 34, 709711. Available from:http://dx.doi.org/10.1016/j.joen.2008.02.043.Langer, R., Vacanti, J.P., 1993. Tissue engineering. Science 260, 920926.Law, A.S., 2013. Considerations for regeneration procedures. J. Endod. 39, S44S56.Available from:http://dx.doi.org/10.1016/j.joen.2012.11.019.Lee, L.-W., Hsiao, S.-H., Hung, W.-C., Lin, Y.-H., Chen, P.-Y., Chiang, C.-P., 2015.Clinical outcomes for teeth treated with electrospun poly(ε-caprolactone) fiber meshes/mineral trioxide aggregate direct pulp capping. J. Endod. 41, 628636. Availablefrom:http://dx.doi.org/10.1016/j.joen.2015.01.007.Lee, W., Oh, J.-H., Park, J.-C., Shin, H.-I., Baek, J.-H., Ryoo, H.-M., et al., 2012.Performance of electrospun poly(ε-caprolactone) fiber meshes used with mineraltrioxide aggregates in a pulp capping procedure. Acta Biomater. 8, 29862995.Available from:http://dx.doi.org/10.1016/j.actbio.2012.04.032.Li, C., Vepari, C., Jin, H.-J., Kim, H.J., Kaplan, D.L., 2006. Electrospun silk-BMP-2scaffolds for bone tissue engineering. Biomaterials 27, 31153124. Available from:http://dx.doi.org/10.1016/j.biomaterials.2006.01.022.Li, W.-J., Danielson, K.G., Alexander, P.G., Tuan, R.S., 2003. Biological response ofchondrocytes cultured in three-dimensional nanofibrous poly(epsilon-caprolactone)scaffolds. J. Biomed. Mater. Res. A 67, 11051114. Available from:http://dx.doi.org/10.1002/jbm.a.10101.Lovato, K.F., Sedgley, C.M., 2011. Antibacterial activity of endosequence root repairmaterial and ProRoot MTA against clinical isolates of Enterococcus faecalis. J. Endod.37, 15421546. Available from:http://dx.doi.org/10.1016/j.joen.2011.06.022.Luu, Y.K., Kim, K., Hsiao, B.S., Chu, B., Hadjiargyrou, M., 2003. Development of ananostructured DNA delivery scaffold via electrospinning of PLGA and PLA-PEGblock copolymers. J. Control. Release Off. J. Control. Release Soc. 89, 341353.Ma, P.X., 2008. Biomimetic materials for tissue engineering. Adv. Drug Deliv. Rev. 60,184198. Available from:http://dx.doi.org/10.1016/j.addr.2007.08.041.Ma, P.X., Zhang, R., 1999. Synthetic nano-scale fibrous extracellular matrix. J. Biomed. Mater.Res. 46, 6072,doi:10.1002/(SICI)109 7-4636(19 9907)46:1,60::AID-JBM7.3.0.CO;2-H.Ma, J., Shen, Y., Stojicic, S., Haapasalo, M., 2011. Biocompatibility of two novel root repairmaterials. J. Endod. 37, 793798. Available from:http://dx.doi.org/10.1016/j.joen.2011.02.029.Marending, M., Stark, W.J., Brunner, T.J., Fischer, J., Zehnder, M., 2009. Comparativeassessment of time-related bioactive glass and calcium hydroxide effects on mechanicalproperties of human root dentin. Dent. Traumatol. 25, 126129. Available from:http://dx.doi.org/10.1111/j.1600-9657.2008.00735.x.Menezes, R., Bramante, C.M., Letra, A., Carvalho, V.G.G., Garcia, R.B., 2004. Histologicevaluation of pulpotomies in dog using two types of mineral trioxide aggregate419References and regular and white Portland cements as wound dressings. Oral Surg. Oral Med. OralPathol. Oral Radiol. Endod. 98, 376379. Available from:http://dx.doi.org/10.1016/j.tripleo.2004.03.008.Mente, J., Hufnagel, S., Leo, M., Michel, A., Gehrig, H., Panagidis, D., et al., 2014.Treatment outcome of mineral trioxide aggregate or calcium hydroxide direct pulpcapping: long-term results. J. Endod. 40, 17461751. Available from:http://dx.doi.org/10.1016/j.joen.2014.07.019.Mohammadi, Z., Khademi, A., 2006. An evaluation of MTA cements as coronal barrier.Iran. Endod. J 1, 106108.Moshaverinia, A., Ansari, S., Movasaghi, Z., Billington, R.W., Darr, J.A., Rehman, I.U.,2008. Modification of conventional glass-ionomer cements with N-vinylpyrrolidonecontaining polyacids, nano-hydroxy and fluoroapatite to improve mechanical proper-ties. Dent. Mater. Off. Publ. Acad. Dent. Mater. 24, 13811390. Available from:http://dx.doi.org/10.1016/j.dental.2008.03.008.Nair, U., Ghattas, S., Saber, M., Natera, M., Walker, C., Pileggi, R., 2011. A comparativeevaluation of the sealing ability of 2 root-end filling materials: an in vitro leakage studyusing Enterococcus faecalis. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod.112, e74e77. Available from:http://dx.doi.org/10.1016/j.tripleo.2011.01.030.Namazikhah, M.S., Nekoofar, M.H., Sheykhrezae, M.S., Salariyeh, S., Hayes, S.J., Bryant,S.T., et al., 2008. The effect of pH on surface hardness and microstructure of mineraltrioxide aggregate. Int. Endod. J. 41, 108116. Available from:http://dx.doi.org/10.1111/j.1365-2591.2007.01325.x.Nejatidanesh, F., Savabi, O., Ebrahimi, M., Savabi, G., 2012. Retentiveness of implant-supported metal copings using different luting agents. Dent. Res. J 9, 1318. Availablefrom:http://dx.doi.org/10.4103/1735-3327.92921.Pal, S., Tak, Y.K., Song, J.M., 2007. Does the antibacterial activity of silver nanoparticlesdepend on the shape of the nanoparticle? A study of the Gram-negative bacteriumEscherichia coli. Appl. Environ. Microbiol. 73, 17121720. Available from:http://dx.doi.org/10.1128/AEM.02218-06.Palasuk, J., Kamocki, K., Hippenmeyer, L., Platt, J.A., Spolnik, K.J., Gregory, R.L., et al.,2014. Bimix antimicrobial scaffolds for regenerative endodontics. J. Endod. 40,18791884. Available from:http://dx.doi.org/10.1016/j.joen.2014.07.017.Parirokh, M., Torabinejad, M., 2010. Mineral trioxide aggregate: a comprehensiveliterature review—part i: chemical, physical, and antibacterial properties. J. Endod. 36,1627. Available from:http://dx.doi.org/10.1016/j.joen.2009.09.006.Park, J.-W., Hong, S.-H., Kim, J.-H., Lee, S.-J., Shin, S.-J., 2010. X-ray diffraction analysis ofwhite ProRoot MTA and Diadent BioAggregate. Oral Surg. Oral Med. Oral Pathol. OralRadiol. Endod. 109, 155158. Available from:http://dx.doi.org/10.1016/j.tripleo.2009.08.039.Persadmehr, A., Torneck, C.D., Cvitkovitch, D.G., Pinto, V., Talior, I., Kazembe, M.,et al., 2014. Bioactive chitosan nanoparticles and photodynamic therapy inhibitcollagen degradation in vitro. J. Endod. 40, 703709. Available from:http://dx.doi.org/10.1016/j.joen.2013.11.004.Prescott, R.S., Alsanea, R., Fayad, M.I., Johnson, B.R., Wenckus, C.S., Hao, J., et al.,2008. In vivo generation of dental pulp-like tissue by using dental pulp stem cells, acollagen scaffold, and dentin matrix protein 1 after subcutaneous transplantation inmice. J. Endod. 34, 421426. Available from:http://dx.doi.org/10.1016/j.joen.2008.02.005.420 CHAPTER 14 Nanobiomaterials in endodontics Rezwan, K., Chen, Q.Z., Blaker, J.J., Boccaccini, A.R., 2006. Biodegradable and bioactiveporous polymer/inorganic composite scaffolds for bone tissue engineering. Biomaterials27, 34133431. Available from:http://dx.doi.org/10.1016/j.biomaterials.2006.01.039.Rolandi, M., Rolandi, R., 2014. Self-assembled chitin nanofibers and applications. Adv.Colloid Interface Sci. 207, 216222, Special Issue: Helmuth Mo¨hwald Honorary Issue.Available from:http://dx.doi.org/10.1016/j.cis.2014.01.019.Roy, A., Bhattacharya, J., 2010. Synthesis of Ca(OH)2nanoparticles by wet chemicalmethod. Micro Nano Lett. IET 5, 131134.Saghiri, M.A., Asatourian, A., Orangi, J., Lotfi, M., Soukup, J.W., Garcia-Godoy, F., et al.,2015a. Effect of particle size on calcium release and elevation of pH of endodontic cements.Dent. Traumatol. 31, 196201. Available from:http://dx.doi.org/10.1111/edt.12160.Saghiri, M.A., Asgar, K., Lotfi, M., Garcia-Godoy, F., 2012a. Nanomodification of mineraltrioxide aggregate for enhanced physiochemical properties. Int. Endod. J. 45, 979988.Available from:http://dx.doi.org/10.1111/j.1365-2591.2012.02056.x.Saghiri, M.A., Garcia-Godoy, F., Asatourian, A., Lotfi, M., Banava, S., Khezri-Boukani,K., 2013. Effect of pH on compressive strength of some modification of mineraltrioxide aggregate. Med. Oral Patol. Oral Cir. Bucal 18, e714e720. Available from:http://dx.doi.org/10.4317/medoral.18922.Saghiri, M.A., Godoy, F.G., Gutmann, J.L., Lotfi, M., Asatourian, A., Sheibani, N., et al.,2014. The effect of pH on solubility of nano-modified endodontic cements. J. Conserv.Dent. 17, 1317. Available from:http://dx.doi.org/10.4103/0972-0707.124096.Saghiri, M.A., Gutmann, J.L., Orangi, J., Asatourian, A., Sheibani, N., 2015b. Radiopacifierparticle size impacts the physical properties of tricalcium silicate-based cements.J. Endod. 41, 225230. Available from:http://dx.doi.org/10.1016/j.joen.2014.09.025.Saghiri, M.A., Lotfi, M., Aghili, H., 2012b. Dental Cement Composition. US20120012030 A1.Saghiri, M.A., Lotfi, M., Saghiri, A.M., Vosoughhosseini, S., Fatemi, A., Shiezadeh, V.,et al., 2008. Effect of pH on sealing ability of white mineral trioxide aggregate as aroot-end filling material. J. Endod. 34, 12261229. Available from:http://dx.doi.org/10.1016/j.joen.2008.07.017.Saghiri, M.-A., Orangi, J., Tanideh, N., Asatourian, A., Janghorban, K., Garcia-Godoy, F.,et al., 2015c. Repair of bone defect by nano-modified white mineral trioxide aggregates inrabbit: a histopathological study. Med. Oral Patol. Oral Cirugia Bucal 20 (5), e525e531.Salvadori, B., Dei, L., 2001. Synthesis of Ca(OH)2nanoparticles from diols. Langmuir 17,23712374.Samavedi, S., Whittington, A.R., Goldstein, A.S., 2013. Calcium phosphate ceramics in bonetissue engineering: a review of properties and their influence on cell behavior. ActaBiomater. 9, 80378045. Available from:http://dx.doi.org/10.1016/j.actbio.2013.06.014.Sato, I., Ando-Kurihara, N., Kota, K., Iwaku, M., Hoshino, E., 1996. Sterilization ofinfected root-canal dentine by topical application of a mixture of ciprofloxacin,metronidazole and minocycline in situ. Int. Endod. J. 29, 118124.Sayed, M., El Saeed, M., 2012. In vitro comparative study of sealing ability of DiadentBioAggregate and other root-end filling materials. J. Conserv. Dent. 15, 249252.Available from:http://dx.doi.org/10.4103/0972-0707.97950.Shabahang, S., Torabinejad, M., Boyne, P.P., Abedi, H., McMillan, P., 1999.A comparative study of root-end induction using osteogenic protein-1, calciumhydroxide, and mineral trioxide aggregate in dogs. J. Endod. 25, 15. Available from:http://dx.doi:10.1016/S0099-2399(99)80388-4.421References Shahi,S.,Rahimi,S.,Yavari,H.R.,Mokhtari,H.,Roshangar,L.,Abasi,M.M.,etal.,2010. E ffect of mineral trioxide aggregates and Portland cements on inflammatorycells. J. Endod. 36, 899903. Available from:http://dx.doi.org/10.1016/j.joen.2010.01.001.Shahi, S., Rahimi, S., Yavari, H.R., Samiei, M., Janani, M., Bahari, M., et al., 2012.Effects of various mixing techniques on push-out bond strengths of white mineraltrioxide aggregate. J. Endod. 38, 501504. Available from:http://dx.doi.org/10.1016/j.joen.2012.01.001.Shayegan, A., Atash, R., Petein, M., Abbeele, A.V., 2010. Nanohydroxyapatite used as apulpotomy and direct pulp capping agent in primary pig teeth. J. Dent. Child. 77,7783.Shayegan, A., Petein, M., Abbeele, A.V., 2008. Beta-tricalcium phosphate, white mineraltrioxide aggregate, white Portland cement, ferric sulfate, and formocresol used aspulpotomy agents in primary pig teeth. Oral Surg. Oral Med. Oral Pathol. Oral Radiol.Endod. 105, 536542. Available from:http://dx.doi.org/10.1016/j.tripleo.2007.10.008.Shi, Z., Huang, X., Cai, Y., Tang, R., Yang, D., 2009. Size effect of hydroxyapatitenanoparticles on proliferation and apoptosis of osteoblast-like cells. Acta Biomater. 5,338345. Available from:http://dx.doi.org/10.1016/j.actbio.2008.07.023.Shokouhinejad, N., Nekoofar, M.H., Ashoftehyazdi, K., Zahraee, S., Khoshkhounejad, M.,2014. Marginal adaptation of new bioceramic materials and mineral trioxide aggregate:a scanning electron microscopy study. Iran Endod. J. 9, 144148.Shrestha, A., Cordova, M., Kishen, A., 2015a. Photoactivated polycationic bioactivechitosan nanoparticles inactivate bacterial endotoxins. J. Endod. 41, 686691.Available from:http://dx.doi.org/10.1016/j.joen.2014.12.007.Shrestha, S., Diogenes, A., Kishen, A., 2015b. Temporal-controlled dexamethasonereleasing chitosan nanoparticle system enhances odontogenic differentiation of stemcells from apical papilla. J. Endod. 41 (8), 12531258. Available from:http://dx.doi.org/10.1016/j.joen.2015.03.024.Shrestha, S., Diogenes, A., Kishen, A., 2014. Temporal-controlled release of bovine serumalbumin from chitosan nanoparticles: effect on the regulation of alkaline phosphataseactivity in stem cells from apical papilla. J. Endod. 40, 13491354. Available from:http://dx.doi.org/10.1016/j.joen.2014.02.018.Shrestha, A., Zhilong, S., Gee, N.K., Kishen, A., 2010. Nanoparticulates for antibiofilmtreatment and effect of aging on its antibacterial activity. J. Endod. 36, 10301035.Available from:http://dx.doi.org/10.1016/j.joen.2010.02.008.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.Smith, I.O., Liu, X.H., Smith, L.A., Ma, P.X., 2009. Nano-structured polymer scaffoldsfor tissue engineering and regenerative medicine. Wiley Interdiscip. Rev. Nanomed.Nanobiotechnol. 1, 226236. Available from:http://dx.doi.org/10.1002/wnan.26.Smith, L.A., Ma, P.X., 2004. Nano-fibrous scaffolds for tissue engineering. Colloids Surf.B Biointerfaces Biointerfaces Nanotechnol. 39, 125131. Available from:http://dx.doi.org/10.1016/j.colsurfb.2003.12.004.Soppimath, K.S., Aminabhavi, T.M., Kulkarni, A.R., Rudzinski, W.E., 2001.Biodegradable polymeric nanoparticles as drug delivery devices. J. Control. ReleaseOff. J. Control. Release Soc. 70, 120.422 CHAPTER 14 Nanobiomaterials in endodontics Srouji, S., Kizhner, T., Suss-Tobi, E., Livne, E., Zussman, E., 2008. 3-D nanofibrouselectrospun multilayered construct is an alternative ECM mimicking scaffold. J. Mater.Sci. Mater. Med. 19, 12491255. Available from:http://dx.doi.org/10.1007/s10856-007-3218-z.Tawil, P.Z., Trope, M., Curran, A.E., Caplan, D.J., Kirakozova, A., Duggan, D.J., et al.,2009. Periapical microsurgery: an in vivo evaluation of endodontic root-end fill-ing materials. J. Endod. 35, 357362. Available from:http://dx.doi.org/10.1016/j.joen.2008.12.001.Thompson, C.J., Chase, G.G., Yarin, A.L., Reneker, D.H., 2007. Effects of parameters onnanofiber diameter determined from electrospinning model. Polymer 48, 69136922.Available from:http://dx.doi.org/10.1016/j.polymer.2007.09.017.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.Torabinejad, M., White, D.J., 1998. Tooth Filling Material and Method of Use. US5769638 A.Tuna, E.B., Dinc¸ol, M.E., Genc¸ay, K., Akto¨ren, O., 2011. Fracture resistance of immatureteeth filled with BioAggregate, mineral trioxide aggregate and calcium hydroxide.Dent. Traumatol. 27, 174178. Available from:http://dx.doi.org/10.1111/j.1600-9657.2011.00995.x.Tziafas, D., Belibasakis, G., Veis, A., Papadimitriou, S., 2001. Dentin regeneration in vitalpulp therapy: design principles. Adv. Dent. Res. 15, 96100.Uskokovi´c, V., Uskokovi´c, D.P., 2011. Nanosized hydroxyapatite and other calciumphosphates: chemistry of formation and application as drug and gene delivery agents.J. Biomed. Mater. Res. B Appl. Biomater. 96, 152191. Available from:http://dx.doi.org/10.1002/jbm.b.31746.Vasita, R., Katti, D.S., 2006. Nanofibers and their applications in tissue engineering. Int.J. Nanomed. 1, 1530.Vollenweider, M., Brunner, T.J., Knecht, S., Grass, R.N., Zehnder, M., Imfeld, T.,et al., 2007. Remineralization of human dentin using ultrafine bioactive glassparticles. Acta Biomater. 3, 936943. Available from:http://dx.doi.org/10.1016/j.actbio.2007.04.003.Walsh, R.M., Woodmansey, K.F., Glickman, G.N., He, J., 2014. Evaluation ofCompressive strength of hydraulic silicate-based root-end filling materials. J. Endod.40, 969972. Available from:http://dx.doi.org/10.1016/j.joen.2013.11.018.Waltimo, T., Brunner, T.J., Vollenweider, M., Stark, W.J., Zehnder, M., 2007.Antimicrobial effect of nanometric bioactive glass 45S5. J. Dent. Res. 86, 754757.Waltimo, T., Mohn, D., Paque´, F., Brunner, T.J., Stark, W.J., Imfeld, T., et al., 2009.Fine-tuning of bioactive glass for root canal disinfection. J. Dent. Res. 88, 235238.Available from:http://dx.doi.org/10.1177/0022034508330315.Wang, J., Liu, X., Jin, X., Ma, H., Hu, J., Ni, L., et al., 2010. The odontogenic differentia-tion of human dental pulp stem cells on nanofibrous poly(L-lactic acid) scaffoldsin vitro and in vivo. Acta Biomater. 6, 38563863. Available from:http://dx.doi.org/10.1016/j.actbio.2010.04.009.Wang, J., Ma, H., Jin, X., Hu, J., Liu, X., Ni, L., et al., 2011. The effect of scaffold archi-tecture on odontogenic differentiation of human dental pulp stem cells. Biomaterials32, 78227830. Available from:http://dx.doi.org/10.1016/j.biomaterials.2011.04.034.423References White, J.D., Lacefield, W.R., Chavers, L.S., Eleazer, P.D., 2002. The effect of threecommonly used endodontic materials on the strength and hardness of root dentin.J. Endod. 28, 828830. Available from:http://dx.doi.org/10.1097/00004770-200212000-00008.Wu, D., Fan, W., Kishen, A., Gutmann, J.L., Fan, B., 2014. Evaluation of the Antibacterialefficacy of silver nanoparticles against Enterococcus faecalis biofilm. J. Endod. 40,285290. Available from:http://dx.doi.org/10.1016/j.joen.2013.08.022.Xie, Y., Chen, Y., Sun, M., Ping, Q., 2013. A mini review of biodegradable calciumphosphate nanoparticles for gene delivery. Curr. Pharm. Biotechnol. 14, 918925.Yamamoto, O., 2001. Influence of particle size on the antibacterial activity of zinc oxide.Int. J. Inorg. Mater. 3, 643646. Available from:http://dx.doi.org/10.1016/S1466-6049(01)00197-0.Yan, P., Yuan , Z. , J iang, H., Peng, B., Bian, Z., 2010. Effect of bioaggregate ondifferentiation of human periodontal l igament fibroblasts. Int. Endod. J. 43,11161121. Available from:http://dx.doi.org/10.1111/j.1365-2591.2010.01786.x.Yang, F., Murugan, R., Wang, S., Ramakrishna, S., 2005. Electrospi nning of nano/microscale poly(L-lactic acid) aligned fibers and their potential in neural tissue engineer-ing. Biomaterials 26, 26032610. Available from:http://dx.doi.org/10.1016/j.biomaterials.2004.06.051.Yang, X., Walboomers, X.F., Van den Dolder, J., Yang, F., Bian, Z., Fan, M., et al., 2008.Non-viral bone morphogenetic protein 2 transfection of rat dental pulp stem cells usingcalcium phosphate nanoparticles as carriers. Tissue Eng. Part A 14, 7181.Yang, X., Yang, F., Walboomers, X.F., Bian, Z., Fan, M., Jansen, J.A., 2010. The performanceof dental pulp stem cells on nanofibrous PCL/gelatin/nHA scaffolds. J. Biomed. Mater.Res. A 93A, 247257. Available from:http://dx.doi.org/10.1002/jbm.a.32535.Yuan, Z., Peng, B., Jiang, H., Bian, Z., Yan, P., 2010. Effect of bioaggregate onmineral-associated gene expression in osteoblast cells. J. Endod. 36, 11451148.Available from:http://dx.doi.org/10.1016/j.joen.2010.03.025.Zare Jahromi, M., Barekatain, M., Ebrahimi, M., Askari, B., 2010. The effect of threeirrigants on the coronal leakage of the root canals system irrigants. Iran Endod. J. 5,121124.Zhang, H., Pappen, F.G., Haapasalo, M., 2009. Dentin enhances the antibacterial effect ofmineral trioxide aggregate and bioaggregate. J. Endod. 35, 221224. Available from:http://dx.doi.org/10.1016/j.joen.2008.11.001.Zhang, S., Yang, X., Fan, M., 2013. BioAggregate and iRoot BP plus optimize the pro-liferation and mineralization ability of human dental pulp cells. Int. Endod. J. 46,923929. Available from:http://dx.doi.org/10.1111/iej.12082.Zhou, H., Shen, Y., Wang, Z., Li, L., Zheng, Y., Ha¨kkinen, L., et al., 2013a. In vitrocytotoxicity evaluation of a novel root repair material. J. Endod. 39, 478483.Available from:http://dx.doi.org/10.1016/j.joen.2012.11.026.Zhou, W., Wang, Y., Jian, J., Song, S., 2013b. Self-aggregated nanoparticles based onamphiphilic poly(lactic acid)-grafted-chitosan copolymer for ocular delivery of ampho-tericin B. Int. J. Nanomed. 8, 37153728. Available from:http://dx.doi.org/10.2147/IJN.S51186.Zhu, L., Yang, J., Zhang, J., Peng, B., 2014. A comparative study of BioAggregate andProRoot MTA on adhesion, migration, and attachment of human dental pulp cells.J. Endod. 40, 11181123. Available from:http://dx.doi.org/10.1016/j.joen.2013.12.028.424 CHAPTER 14 Nanobiomaterials in endodontics

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