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Efficacy of a 10-MDP containing cleaner on the bond strength to contaminated dentin

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Efficacy of a 10-MDP containing cleaner on the bond strength to contaminated dentin

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Efficacy of a 10-MDP Containing Cleaner on the Bond Strength to
Contaminated Dentin

by

Rie Hayashi-Wells, DDS

A Thesis Presented to the
FACULTY OF THE USC HERMAN OSTROW SCHOOL OF DENTISTRY
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirement for the Degree
MASTER OF SCIENCE
BIOMATERIALS AND DIGITAL DENTISTRY

December 2020

Copyright 2020 Rie Hayashi-Wells

ii
Acknowledgements
It is with much gratitude that I would like to recognize the committee members for their
generously with their time and unwavering support throughout my tenure at USC. A very special
thanks to Dr. Jin-Ho Phark, the committee chairman, and my advisor for the countless hours of
guidance, reassurance, and kind support. Because of his advice I was able come this far and
reach new heights in not only the master course, but throughout the entire program.

I would also like to thank Dr. Sillas Duarte, my mentor and co-advisor, who helped me
throughout this dual program to become a better clinician and supported my first experience in
the research part of dentistry. It was not an easy tenure, but this last 2 years were a period of
immense growth for me and I owe a great deal of this to Dr. Duarte for this opportunity.

Additionally, I would like to thank Dr. Alena Knezevic for always teaching us a dedication to
excellence and to enjoy the learning process. I appreciate the many tips you shared, how you
showed us the importance of referencing the literature and how you never hesitated to share your
vast knowledge. Also, as a female doctor, her achievements professionally and in her private life
always encouraged me to be my best inside and outside the clinic.

To Dr. Neimar Sartori, thank you for teaching me the importance of evidence-based dentistry, of
how to work efficiently, and that the details in dentistry make all the difference. Thanks for
sharing all your knowledge and tricks of the trade in the clinic to become a better clinician.

iii
To Dr. Pinghui Feng and his residents, thank you for letting me use your laboratory and treating
me with great kindness. To Mrs. Karen Guillen, thanks for your constant support, and for
providing me any assistance when needed.
I would like to thank my co-residents for their constant support and words of encouragement. I
was fortunate to have peers that were always there for me to work hard and enjoy the process
with. All of my co-residents are tremendously hard workers and I truly believe we supported
each other well to do our best.
I would also like to thank my family and friends for the constant support and for always
believing in me. Especially during this awful pandemic and difficult time, I’m blessed to have
this level of support to finish my post-doctorate students on a positive note.
Finally, I would like to convey my gratitude to my dear husband for loving me unconditionally,
expanding my horizons, putting up with my late-night study sessions, and supporting me along
the way.
I feel fortunate to have had this opportunity with so many brilliant and supportive people around
me. This program has been a profound learning experience, an unforgettable phase in my
training that pushed me to become a better dentist and a better human being—thank you to all
that helped make it happen.

iv
Table of Contents
Acknowledgements ............................................................................................................ ii
List of Tables ...................................................................................................................... vi
List of Figures ................................................................................................................... vii
Abbreviations ...................................................................................................................... x
Abstract ............................................................................................................................... xi
Introduction ......................................................................................................................... 1
Objectives .......................................................................................................................... 11
Materials and Methods ...................................................................................................... 12
Specimen fabrication ..................................................................................................... 12
Smear layer preparation ................................................................................................. 15
Contamination ............................................................................................................... 15
Cleaner application ........................................................................................................ 16
Bonding protocol ........................................................................................................... 16
Artificial aging ............................................................................................................... 19
Notch-edge shear bond strength testing ........................................................................ 19
Failure mode .................................................................................................................. 20
Ultrastructural evaluation .............................................................................................. 20
Statistical analysis ......................................................................................................... 23
Results ............................................................................................................................... 24
Notch-edge shear bond strength analysis ...................................................................... 24
Failure analysis .............................................................................................................. 27
Ultrastructural evaluation .............................................................................................. 29
Discussion .......................................................................................................................... 32
Verification of using a universal adhesive system in self-etch mode ............................ 32
Longevity of 10-MDP containing universal adhesive agent in SE mode ...................... 33
Contamination ............................................................................................................... 34

v
Cleaning agent ............................................................................................................... 36
Contamination and cleaning agent ................................................................................ 38
Other factors possibly contributing to bond strength .................................................... 42
Study Limitations .......................................................................................................... 43
Conclusion ......................................................................................................................... 49
Conflict of interest ............................................................................................................. 50
IRB .................................................................................................................................... 51
Funding .............................................................................................................................. 52
References ......................................................................................................................... 53

vi
List of Tables
Table 1: Experimental set-up ........................................................................................... 14
Table 2: Composition of material .................................................................................... 18
Table 3: Sample preparation for FeSEM ......................................................................... 22
Table 4: Notch-edge shear bond strength in MPa ± SD ................................................... 24
Table 5: Descriptive statistics for shear bond strength by group ..................................... 25
Table 6: Test of homogeneity of variance ........................................................................ 26
Table 7: Tests of between-subject effects on shear bond strength for three-way ANOV A
..................................................................................................................................................... 26
Table 8: Tests of between-subject effects on shear bond strength for one-way ANOV A . 27

vii
List of Figures
Figure 1: 10-MDP ............................................................................................................. 8
Figure 2: Micelle structure ................................................................................................ 9
Figure 3: Application ......................................................................................................... 9
Figure 4: Activation ........................................................................................................... 9
Figure 5: Aggregation ....................................................................................................... 9
Figure 6: Removing ......................................................................................................... 10
Figure 7: Rinsing ............................................................................................................. 10
Figure 8: Sample tooth after polishing with pumice and prophy cup .............................. 13
Figure 9: Horizontal line 2.5mm from cusp tips ............................................................. 13
Figure 10: Axial line separating into two halves ............................................................. 13
Figure 11: Horizontal section removing coronal enamel and exposing mid-dentin ........ 13
Figure 12: Axial section after cutting into halves ............................................................ 13
Figure 13: Final samples after removing pulpal tissue .................................................... 13
Figure 14: Finished samples ............................................................................................ 13
Figure 15: Finished samples (bonding surface) ............................................................... 13
Figure 16: Experimental set-up (workflow) .................................................................... 14
Figure 17: Cleaner application ........................................................................................ 16
Figure 18: Specimen placed in clamping device with a bonding mold insert ................. 17
Figure 19: Adding two increments of composite resin .................................................... 17
Figure 20: Light curing immediately on top of the mold ................................................ 17
Figure 21: Final samples after bonding procedure .......................................................... 18

viii
Figure 22: Universal testing machine .............................................................................. 20
Figure 23: Close up of machine with specimen placed in loading jig and semicircular
notch-edge loading blade ............................................................................................................. 20
Figure 24: Bonded specimen placed in loading jig ......................................................... 20
Figure 25: Sample preparation for FeSEM (Workflow) .................................................. 23
Figure 26: Notch-edge shear bond strength (MPa) by groups ......................................... 25
Figure 27: Overall failure mode analysis by failure type ................................................ 27
Figure 28: Failure mode analysis in absolute numbers by groups ................................... 28
Figure 29: Failure mode analysis in percentage by groups ............................................. 29
Figure 30: FeSEM-K ....................................................................................................... 30
Figure 31: FeSEM-SU ..................................................................................................... 30
Figure 32: FeSEM-K+SU ............................................................................................... 30
Figure 33: FeSEM-C+K .................................................................................................. 31
Figure 34: FeSEM-C+SU ................................................................................................ 31
Figure 35: FeSEM-C+K+SU ........................................................................................... 31
Figure 36: Dentin surface contaminated by saliva .......................................................... 39
Figure 37: Saliva protein adhering to loose calcium ion in smear layer .......................... 39
Figure 38: Application of 10-MDP containing cleaner ................................................... 40
Figure 39: Rinsing with water ......................................................................................... 40
Figure 40: Saliva protein and adhered loose calcium ion washed away after rinsing ..... 40
Figure 41: Adhesive agent application ............................................................................ 40
Figure 42: Penetration of adhesive agent ........................................................................ 40

ix
Figure 43: Dentin surface contaminated by saliva .......................................................... 41
Figure 44: Salivary protein aggregating loose calcium ion creating spaces .................... 41
Figure 45: Adhesive application ...................................................................................... 41
Figure 46: Adhesive agent penetration ............................................................................ 41

x
Abbreviations
A: Aging
C: Contamination
EDTA: Ethylendiaminetetraacetic Acid
GCF: Gingival Crevicular Fluid
GPDM: glycerolphosphate dimethacrylate
HAp: Hydroxyapatite
HEMA: 2-Hydroxyethyl Methacrylate
ISO: International Organization for Standardization
MID: Minimally Invasive Dentistry
MTEGP: 10-methacryloyloxy tetraethylene glycol dihydrogenphosphate
NaOCl: Sodium hypochlorite
Phenyl-P: 2-methacryloxyethylphenyl hydrogenphosphate
K: Katana Clean
SBS: Shear Bond Strength
SE: Self-etch
FeSEM: Field-emission Scanning Electron Microscopy
SU: Scotchbond Universal
TEM: Transmission Electron Microscope
4-META: 4-methacryloyloxyethy trimellitate anhydride
6-MHP: 6-methacryloy- loxyhexyl dihydrogenphosphate
10-MDP: 10-Methacryloyloxydecyl dihydrogen phosphate

xi
Abstract
Title: Efficacy of a 10-MDP containing cleaner on the bond strength to contaminated dentin
Objectives: The aim of this study was to examine the effect of saliva contamination and a 10-
MDP containing tooth cleaner on the notched shear bond strength (SBS) to human dentin using a
universal adhesive system in self-etch mode.
Materials and methods: One hundred and seven extracted intact human molars were sectioned
to expose mid-coronal dentin. Selected specimens were embedded into acrylic resin and divided
into 4 groups (n=40): Smear layer was created in all specimens. Group SU (control), bonding
completed after smear layer creation; Group C+SU, contamination with saliva before bonding;
Group K+SU, tooth cleaner applied before bonding; and Group C+K+SU, contamination with
saliva then tooth cleaner application before bonding. All groups (n=40) were divided into two
subgroups. One subgroup was tested for notched SBS 24 h after specimen fabrication, the other
subgroup after thermal cycling (20,000 cycles). Failure mode was examined with a stereo
microscope and the treated tooth surface was observed with SEM. Statistical analysis was
performed using a 1- and 3-way ANOV A at α=0.05.
Results: The results reveal the data ranged from 9.69 ± 6.03 MPa (C+SU+A) to 16.98 ± 6.53
MPa (SU+A). The only significant factor influencing SBS was contamination (p=0.002). Failure
mode was predominantly “adhesive at dentin” (63.3%). SEM images revealed K+SU enhanced
etching and no bacteria were seen.
Conclusion: Saliva contamination affects the longevity of one ultra-mild universal adhesive
system. Application of 10-MDP containing tooth cleaner does not completely remove the smear
layer or plugs and has no influence on bond strength.

xii
Clinical significance: Upon bonding restorations, a completely clean tooth surface is essential.
To achieve such a surface before performing the bonding procedure, clinicians benefit from
using decontamination agents without damaging tooth structure and without interfering with the
bonding mechanism. The 10-MDP containing tooth cleaner does not influence the bond strength
of a universal adhesive agent.

Key Words: Universal adhesives, Dentin, Cleaner, 10-MDP, Saliva, SBS

1
Introduction
The development of dental technology and dental materials has drastically improved in the
past decade, along with changing treatment approaches from “Extension for prevention” to
“Prevention of Extension”
(1)
.

As a result, minimally invasive dentistry (MID) has become a trend
in dentistry today, and more adhesive treatment is being practiced
(2)
.
The concept of tooth bonding was first described by Michael Buonocore in 1955
(3)
.

The 1
st

and 2
nd
generations of adhesive systems mainly focused on enamel bonding by establishing a
chemical bond to acid etched enamel with different functional monomers, such as,
glycerophosphate dimethacrylate (GPDM), and phosphorus ester of methacrylate derivatives
(4)
.
However, these early adhesives presented very low bond strength because these systems were
not able to remove the smear layer or smear plugs created by bur preparation, they were not able
to bond to pure dentin substrate
(5)
. From the 3
rd
generation on, researchers started to focus on
acid etching of dentin to remove smear layer and smear plugs in order to increase bond strength
by creating partial or full demineralization of dentin before infiltration of monomers to create the
so called “Hybrid Layer”
(6, 7)
. To be able to infiltrate into dentin, hydrophilic monomer, such as,
2-hydroxyethyl methacrylate (HEMA) was added as part of the two-step adhesive agent
(5, 8)
.
Initially, the acid that was used was too strong, causing pulpal damage
(6, 9)
.

To avoid pulpal
damage, Fusayama
(10)
and his research group employed milder acids establishing the “total-etch”
concept, also known as the “etch and rinse” or 4
th
generation of adhesive systems; this became
the “gold standard” of adhesive systems
(5, 11, 12)
. For the next generation, researchers aimed to
simplify the application. Therefore, the 5
th
generation combined primer and bonding agent
together in one bottle (2-step etch and rinse system)
(13)
.

The 4
th
and 5
th
generations use

2
phosphoric acid as an etching agent; the drawback of some of these products is that etching
effect was too strong, that the adhesive agent was not able to fully infiltrate the etched dentin,
which led to gap formation in the hybrid layer
(14, 15)
. As a result, nanoleakage occurred, which
further caused degradation of adhesive monomers and hydrolysis of dentin collagen fibers
(14, 15)
.
Therefore, instead of using a separate acid etching agent, self-etching primers were introduced
with the 6
th
generation (2-step self-etch adhesives)
(13)
. They use an acidic monomer in the
primer, for example, 4-methacryloyloxyethl trimellitate (4-MET), 10-methacryloyloxydecyl
dihydrogen phosphate (10-MDP), 2-methacryloxyethylphenyl hydrogenphosphate (Phenyl-P)
(16,
17)
thus allowing to omit the water rinsing step; therefore, these agents were also called etch-and-
dry systems. These self-etch adhesives can be further sub-grouped according to the intensity of
acidic monomers: ‘strong’ (pH<1), ‘intermediary strong’ (pH=1-2), ‘mild’ (pH≈2), and ‘ultra-
mild’ (pH>2.5) self-etch adhesives
(13)
. Then, 1-step self-etch adhesives or all-in-one adhesives
were introduced with the 7
th
generation adhesives
(5, 13)
. When evaluating self-etch primers with
different acidity, “ultra-mild” self-etch adhesives were found to be more promising in providing
micromechanical interlocking with and chemical bonding to dentin
(14-19)
. The most recent
generation of adhesive systems, the 8
th
generation adhesives or universal adhesive systems, have
become very popular because of their simplicity in terms of application and the availability of
various application methods based on the clinicians’ choice
(5)
. Universal adhesive systems can be
applied in 3 different modes, such as etch-and-rinse mode, self-etch mode, or a combination of
both methods by using selective etch-and-rinse mode on enamel and the one-step self-etch mode
for dentin
(5)
.

In the presence of enamel on the bonding surface, selective enamel etching is
recommended, during which enamel is etched separately with phosphoric acid to achieve
sufficient micromechanical interlocking to successfully obtain long-lasting adhesion
(5)
.

3
In the universal adhesive systems, the mechanical properties, bond strength, and degree of
conversion of universal adhesives have been improved compared to other adhesive systems
(5, 20)
.
In particular, universal adhesives containing 10-MDP as its functional monomer are believed to
be able to create a water resistant layer called a nanolayer at the resin-dentin interface
(21, 22)
. The
monomer 10-MDP has bifunctional characteristics: via its hydrophilic phosphoric group one end
bonds chemically to Ca
2+
from hydroxyapatite (HAp), with the other end that contains a
hydrophobic spacer ester chain and an acryloyl group it can interact with acrylic materials
(22, 23)
.

This acryloyl group facilitates polymerization and promotes chemical coupling with unsaturated
carbon links in the matrix resin of the substrate, and the hydrophobic spacer ester chain prevents
breakthrough of water into the adhesive layer
(22, 23)
. As a result, this hydrophobic end becomes
water resistant and prevents or decreases hydrolysis, such as monomer leaching, water
absorption, and degradation of collagen fibers
(12, 22-24)
. According to the theory of the “Adhesion–
Decalcification concept” (A–D concept), which explains the interactions of acidic molecules
with HAp, in the first phase, all acidic monomers bond ionically to the calcium of HAp
(25, 26)
. If
the ionic bond is hydrolytically stable, the molecules will stay bonded
(25, 26)
. However, if the
ionic bond becomes unstable in the second phase, it will de-bond and the calcium will be
detached from the tooth surface, causing demineralization and enhancing hydrolysis
(25, 26)
. 10-
MDP, as a functional monomer containing a phosphate end, could develop a stable phosphate-
calcium ionic bond with calcium in the tooth structure or the smear layer, and spontaneously
create the area of a hydrophobic layered structure at the bonding surface, also called nanolayer
(21,
22)
. This hydrolytic stability of 10-MDP-Ca salts could be associated with the chemical property
of long and hydrophobic spacer chains of 10-MDP. This unique amphiphilic property of 10-
MDP and the subsequently stable and strong adhesion to the calcium in HAp have appeared to

4
supplement the durability of the bond as well as increase the initial bonding performance of self-
etching adhesives
(27-30)
. However, nanolayer formation is not always found in all 10-MDP
containing self-etch or universal adhesive systems
(27)
. According to Yoshihara et al
(31, 32)
,
nanolayer formation is affected by multiple factors, such as 10-MDP concentration and purity,
application mode, and the structure of the functional monomers.

While adhesive systems and bonding techniques have greatly evolved today, bonding to
dentin still remains challenging and questionable
(5)
. Reasons for this are the opposite
hydrophilicity between dentin and composite materials, and the difficulty of creating a durable
intermediate layer. Enamel is composed of higher amounts of inorganic components and less
organic components or water than dentin, which helps obtain dryer surface that is favorable
environment for an adhesive procedure and the result is predictable
(13, 17)
. In contrast, dentin is a
living tissue containing lesser inorganic and more organic components, and water, which makes
bonding surface hydrophilic
(33)
. In order to achieve successful bonding, the so called hybrid
layer, an intermediate layer between hydrophilic dentin and hydrophobic composite resin, must
be established and remain hydrolytically stable
(6, 7)
. Therefore, factors such as quality of the
adhesive system, the amount of moisture, and the cleanness of the bonding surface are essential
to achieve stable, long-term adhesion
(34, 35)
.
When the tooth structure is prepared, surface contamination cannot be avoided. One of
the reasons is the creation of a smear layer. The smear layer consists of organic (salivary
proteins, blood, bacteria/plaque, food remnants, plasma, gingival crevicular fluid (GCF), tooth
debris (collagen) and oil from handpieces)
(36)
and inorganic debris (salivary ions, temporary
cement, bases, liners, impression materials, tooth debris or hydroxyapatite, water and saline)
(35)

5
created during tooth preparation
(6, 37)
. To remove the smear layer or smear plugs effectively, etch
and rinse adhesive systems were used with 37% phosphoric acid which can completely
demineralize about 5-8 micrometer of the intertubular dentin matrix and with water to wash
debris away resulting in a clean dentin surface
(38)
. However, because of the strong acidity of
phosphoric acid, when used on dentin surfaces it can cause pulpal sensitivity and fluid movement
out of dentinal tubules onto the adhesive surface, resulting in dilution of the primer, incomplete
infiltration of resin around collagen fibril matrices, and nanoleakage
(39)
. Therefore, using 37%
phosphoric acid on dentin surface was not ideal
(5)
.

Instead, the self-etch approach, which omits
the phosphoric acid step, is recommended for dentin surface
(17)
. In common, acidic monomers
(10-MDP, 4-MET, Phenyl-P) in self-etch adhesive systems or multimode systems used in self-
etch mode exclude the rinsing step of bonding steps makes it easier and faster for clinicians to
treat
(17, 20)
; however, this cannot completely remove the smear layer
(17, 40, 41)
. Instead, it will
soften the inorganic components of the smear layer and diffuse or loosen them, thus allowing the
adhesive monomers to infiltrate in order to create a hybrid layer
(40)
. This remaining smear layer
at the bonding interface is a drawback because it affects the bond strength of universal adhesive
systems by blocking the resin monomer infiltration into dentin, causing weaker bond strength
(17,
42, 43)
.
Another factor influencing the bonding capability of universal adhesives is caused by its
environmental condition since the fluid contamination in the oral cavity can occur
(44)
. Bonding is
very sensitive to contamination by moisture from water, saliva, blood, sulcular fluid, or oil
(35, 36,
44)
. One of the most common contaminants is saliva, which usually occurs in case of lack of
isolation
(45)
. Saliva is composed of mostly water, which contains organic compounds (e.g.,
glycoproteins, proline-rich protein, statherine, immunoglobulins), inorganic compounds (e.g.,

6
calcium, chloride, phosphate ions), and enzymatic molecules (e.g., α-amylase, perosidase,
lysozyme)
(46)
.

Large molecular weight particles in saliva will be dispersed onto the dentin surface
and into the dentinal tubules
(44)
. These macromolecules might interfere with the diffusion process
of resin monomers in adhesive systems during the application of adhesive, resulting in
insufficient bond strength
(44, 45)
. Additionally, not only saliva, but also other organic components,
such as blood, plaque, proteins, and oral bacteria, have been confirmed in multiple studies as
adhesion inhibiting factors
(44, 47-49)
. It was reported that saliva contamination could reduce the
dentin bond strength by 30% to 40%
(49)
. Moreover, the use of an air-water syringe was not
capable of complete elimination of saliva contamination
(50)
. Furthermore, the water content in
saliva will dilute the adhesive material
(19, 41, 50, 51)
, reducing the resin monomer degree of
conversion
(19, 38, 52)
,

thus leading to nanoleakage in the adhesive layer with subsequent failure of
the restoration
(38, 53, 54)
.
To achieve successful results and longevity of bonded restorations, adhesion inhibiting
factors must be eliminated before proceeding with the bonding procedure
(55)
. Removing the
organic phase of the contaminant could enhance the infiltration of the adhesives into dentin, thus
eliminating gaps of infiltration to avoid the weak adhesive interface of the hybrid layer
(41, 43, 49,
51)
. This fact suggests the possibility of improving bond strength if there is a cleaning agent that
can be applied before the bonding procedure that will not affect or modify the bonding
mechanism and chemical interaction between the adhesive agent and tooth structure.
In the past, many different agents were used as dentin pretreatment to clean the bonding
surface. Slurry of pumice and prophy paste were used, however, they removed large molecules
of stain or cement residue only without removing the smear layer
(56)
. 17%

7
ethylendiaminetetraacetic acid (EDTA) was able to remove the smear layer partially, however,
organic components still remained
(57)
. Other cavity cleaners contained 2-butanone and ethyl
acetate, chlorhexidine digluconate and sodium fluoride, or 3% hydrogen peroxide; however,
none of them were able to completely remove the smear layer or smear plugs
(58-60)
. Sodium
hypochlorite (NaOCl) was able to remove the smear layer and large organic contaminants
(61, 62)
,
however, the remaining super-oxide radicals in the tooth can interfere with polymerization of the
resin monomers of the adhesive, causing adhesive failures
(23, 63-65)
. Therefore, in case of using
NaOCl as a dentin pre-treatment agent, an antioxidant is needed before bonding to completely
remove residual oxygen from the tooth structure to avoid inhibition of resin polymerization by
oxygen from NaOCl
(64, 65)
. In addition, NaOCl is known to cause oral mucosa irritation and
possible mucosal burn when it comes in contact with oral tissue, thus, caution is needed for
clinical application and a rubber dam placement suggested
(64)
. Also, 2% chlorhexidine and
titanium tetrafluoride were used to clean the surface, and these anti-bacterial agents served as a
matrix metalloproteinase inhibitor on acid etched dentin to avoid degradation of hybrid layer,
however, no effect on smear layer removal was reported
(58, 59)
. Lastly, researchers tried different
acids to remove organic and inorganic contaminants by re-etching the bonding surface with 35-
37% phosphoric acid or 40% poly acrylic acid
(66, 67)
. Both were effective in removing
contaminants, however, doubling acid exposure and etching time by re-etching can cause post-
operative sensitivity and alter the collagen network of dentin to cause nanoleakage, therefore, the
longevity of restoration did not improve
(56, 66, 67)
.
Recently, a 10-MDP containing non-abrasive dental cleaning agent (KATANA cleaner;
Kuraray Noritake, Okayama, Japan) was introduced for the purpose of cleaning the bonding
surface of restorations after try-ins as well as the tooth surface before bonding or cementing
(68)
.

8
This cleaning agent is aimed to eliminate the adhesion inhibiting factors that may be present on
both, the restorative and the tooth surface, allowing to achieve maximum bond strength possible
to the cleaned surface.
The mechanism of KATANA cleaner is described through the surfactant activity of the
MDP salt via micelle formation which can maintain a mild acidity of about pH 4.5 on the tooth
surface to remove the organic components of contaminants
(68)
. Research has shown that 10-MDP
is a bifunctional monomer containing hydrophilic and hydrophobic compartments in a molecule
(Figure 1)
(22, 23, 69)
. Because of its amphiphilic properties, it reacts as a nonionic surfactant that
tends to aggregate and form a micelle structure with its hydrophilic domains exposed, and the
hydrophobic contents drain inside of the micelle (Figure 2)
(70, 71)
. This makes 10-MDP a suitable
ingredient for a cleaning solution. When the 10-MDP containing solution is applied to the tooth
surface (Figure 3), the micelle structure opens up and the hydrophobic compartment of 10-MDP
and the hydrophobic saliva protein surface bind together (Figure 4).

Mechanism of cleaning by 10-MDP containing cleaner
Figure 1: 10-MDP
10-MDP is a bifunctional monomer presents hydrophilic and hydrophobic compartments
in a molecule.

9
Figure 2: Micelle structure
Because of its amphiphilic properties, it can react as nonionic surfactants and aggregates
to form a micelle structure with its hydrophilic domains outside and hydrophobic domain inside.
Figure 3: Application
10-MDP containing tooth cleaner applied onto the tooth.
Figure 4: Activation
The micelle structure opens up and binds to the saliva proteins.

As more and more 10-MDP molecules aggregate around the saliva protein, it
encapsulates these particles and breaks into smaller particles (Figure 5). As a result, the
hydrophilic domains facing the aqueous environment making it possible to be rinsed away by
water, and the dye in the hydrophilic domain becomes the indicator of cleaning agent’s removal
from the surface (Figure 6, Figure 7)
(68)
.

Mechanism of rinsing 10-MDP containing cleaner
Figure 5: Aggregation
As more 10-MDP molecules aggregate around the salivary protein, it encapsulates and
breaks down.

10
Figure 6: Removing
The hydrophilic domains face the aqueous environment and starts to remove the salivary
protein from the surface.
Figure 7: Rinsing
After water irrigation, the cleaner and the protein together will be washed away.

Other commercial cleaners, such as, IVOCLEAN (Ivoclar Vivadent, Inc. Amherst, N.Y.,
USA) and ZIRCLEAN (BISCO, Inc. Schaumburg, IL., USA) use sodium hydroxide or
potassium hydroxide as their active cleaning agents; both are water soluble, can be rinsed away
with water, and require short application time (20 s with rubbing motion)
(72, 73)
. However, the pH
of these cleaning agents is highly alkaline, about pH 13 to 13.5, so that neither of them can be
used intraorally nor directly applied onto the tooth surface
(72, 73)
. Therefore, this 10-MDP
containing tooth cleaner seems to be the only product on the market possibly able to remove
contaminants without damaging the tooth structure.
It is clear that in order to achieve successful adhesion, excess of moisture, contamination
created by the oral environment and tooth preparation must be adequately removed from the
bonding surface for the adhesive material to infiltrate uniformly into the tooth structure without
forming gaps or voids. Also, when using a dental cleaning agent, no residue of the agent should
remain to avoid any adhesion inhibition activity or change in the degree of conversion of the
adhesive material. In order to verify the efficacy of this new product, this in vitro study is
needed.

11
Objectives
The objective of this study is to evaluate the influence of human saliva contamination and
a novel MDP-containing dental cleaning agent (KATANA cleaner; Kuraray Noritake Aichi
Japan) on the notched shear bond strength of a universal adhesive system to human dentin.
Furthermore, the study aims to compare the longevity of the bond and to observe the fracture
mode and surface morphology to analyze the effects of all factors involved.
This study was designed to test the following null hypotheses:
(1) There is no difference in bond strength of a universal adhesive system to human dentin
after contamination with human saliva
(2) There is no difference in bond strength of a universal adhesive system to saliva
contaminated and non-contaminated human dentin after using an MDP-containing dental
cleaning agent.
(3) Artificial aging does not influence the bond strength regardless of contamination or
cleaning agent.

12
Materials and Methods
Specimen fabrication
This study was approved by USC Ethical Committee, IRB number: APP20-04357. A total
of 107 intact, non-caries human extracted molar teeth were used in this study. All teeth were
cleaned with a fine pumice and prophy cup and stored in distilled water at room temperature
until further testing. Each tooth was mounted on a custom-made aluminum jig with sticky wax
(Sticky Wax,

Kerr, Brea, CA, USA). The occlusal enamel was removed about 2.5 mm from the
cusp tips to expose dentin structure by using a precision sectioning saw (IsoMet 1000; Buehler,
Lake Buff, IL, USA) equipped with a diamond blade (102 mm diameter, 0.3 mm thickness;
IsoMet Blade, 15LC, Buehler, Lake Buff, IL, USA) at a the speed of 800 RPM perpendicular to
the long axis of the tooth under lubrication with distilled water at room temperature (Figure
11)
(74)
.

Then, each of the exposed dentin surfaces was sectioned into two halves by using the
diamond blade parallel to the long axis of the tooth (Figure 12); pulpal tissue was removed from
the pulpal chamber with dental tweezers (Figure 13). Teeth with smaller diameters were not
sectioned, and teeth with sclerotic dentin or discoloration from pulpal inflammation were
discarded.

Tooth sectioning

13
Figure 8: Sample tooth after polishing with pumice and prophy cup
Figure 9: Horizontal line 2.5mm from cusp tips
Figure 10: Axial line separating into two halves
Figure 11: Horizontal section removing coronal enamel and exposing mid-dentin
Figure 12: Axial section after cutting into halves
Figure 13: Final samples after removing pulpal tissue

Using a silicone mold (10 mm x 10 mm x 10 mm cubic, Z-DUPE Henry Schein,
Melville, NY , USA), each specimen was embedded into self-curing denture acrylic resin
(Palapress® Vario, clear shade, Heraeus Kulzer, Hanau, Germany) leaving the targeted bonded
tooth surface exposed (Figure 14, Figure 15). After polymerization, each specimen was
numbered. They were divided into four groups of 40 specimens in numerical order, then, stored
in distilled water at 37°C until further processing (Table 1)
(75)
.

Embedded specimen
Figure 14: Finished samples
Figure 15: Finished samples (bonding surface)

14
Table 1: Experimental set-up
Substrate: Human dentin with smear layer (600 grit, 60 s)
Saliva
Contamination (C)
N Y N Y
Katana Cleaner (K) N N Y Y
Bonding agent: Scotchbond Universal in self-etch mode (SU)
20,000 cycles of
Thermal Cycling (A)
N (N=20) Y (N=20) N (N=20) Y(N=20) N (N=20) Y (N=20) N(N=20) Y(N=20)
Groups SU SU+A C+SU C+SU+A K+SU K+SU+A C+K+SU C+K+SU+A
Notched shear bond strength testing
Failure mode analysis by Microscope and SEM

Figure 16: Experimental set-up (workflow)
Group SU (Control): Smear layer preparation and bonding procedure
Group SU+A: Smear layer preparation, bonding procedure, and thermal cycling
Group C+SU: Smear layer preparation, contamination, bonding procedure
Group C+SU+A: Smear layer preparation, contamination, bonding procedure, and thermal cycling
Group K+SU: Smear layer preparation, cleaning agent application, and bonding procedure
Group K+SU+A: Smear layer preparation, cleaning agent application, bonding procedure, and thermal
cycling
Group C+K+SU: Smear layer preparation, contamination, cleaning agent application, and bonding
procedure
Group C+K+SU+A: Smear layer preparation, contamination, cleaning agent application, bonding
procedure, and thermal cycling
Y: Yes
N: No

15
Smear layer preparation
To create a standardized smear layer on all specimens, the bonding surface of each
specimen was polished with silicon carbide grinding papers (CarbiMet Abrasive Sheet, 600, SiC,
Lake Buff, IL, Buehler) under irrigation with distilled water at room temperature for 60 s
(37)
.
This was followed by rinsing with distilled water for 30 s and air drying at a distance of 20 mm
from the surface for 5 s
(76)
.

For all the specimens, smear layer preparation was performed by the
same investigator.

Contamination
Unstimulated human saliva (resting) 30 ml was collected into a plastic container from a
consenting healthy investigator. Prior to collection, the saliva donor had refrained from eating,
drinking, toothbrushing, or rinsing for 2 h; the saliva was collected in the morning over a time
frame of about three hours
(77)
. Salivary pH was measured with a saliva pH indicator (Saliva-
Check Buffer, GC America Inc).
To simulate intraoral contamination, the bonding surfaces of specimens from Groups
C+SU and C+K+SU (Table 1) were immersed in saliva for 60 s, rinsed with distilled water for
15 s, and air dried at a distance of 20 mm from the surface for 5 s
(77)
. The contamination took
place immediately before the bonding procedures.

16
Cleaner application
For specimens in Groups K+SU and C+K+SU (Table 1), a cleaning solution was applied
(Katana Cleaner, Kuraray Noritake, Okayama, Japan) and rubbed onto the contaminated bonding
surface with a micro-brush for 15 s (IFU states for more than 10 s) (Figure 17)
(78)
.

Figure 17: Cleaner application
10-MDP containing dental cleaning agent (Katana Cleaner, Kuraray Noritake, Okayama Japan)

Distilled water was used for 10 s to rinse the cleaning solution from the bonding surface
until the purple colored cleaning solution had completely disappeared from the specimen. The
bonding surface of each specimen was dried gently with air for 5 s using oil-free air at a distance
of 20 mm. Specimens were processed for bonding immediately after this step.

Bonding protocol
The bonding procedure was performed according to the manufacturer’s instructions. A
universal bonding agent (Scotchbond Universal, 3M, St. Paul, MN) (Table 2) was applied to the
bonding surface with a rubbing motion for 20 s. Subsequently, the bonding agent was thinned out
and the solvent was evaporated using oil-free air for 5 s, 10 mm away from the bonding surface,
while ensuring no visible excess existed. Next, the bonding agent was light cured for 10 s using a

17
LED light curing unit (Valo, Ultradent, South Jordan, UT, USA) at standard power mode (1000
mW/cm
2
, wavelength 385-515 nm), about 1 mm away from the bonding surface without
touching it. Next, the specimens were placed into a clamping device equipped with bonding
mold inserts (Bonding clamp and bonding mold insert, Ultradent, South Jordan, UT, USA)
mounted directly over the dentin bonding surface by gently tightening the thumb nuts until they
lightly press on the springs (Figure 18). Then, a nano-hybrid composite (IPS Empress Direct
A1E, Ivoclar Vivadent, Amherst, NY , USA) was layered into the molds in two increments to
fabricate composite cylinders with 2.38 mm diameter and 3 mm height (Figure 19). For this
purpose, the mold was filled with composite material up to half of the mold’s depth, light cured
at standard power mode for 20 s with the lens of the light curing unit placed immediately on top
of the bonding mold (Figure 20)
(79)
. Then, in the same fashion, the mold was filled up to the top
with composite, which was subsequently light cured.

Bonding procedure
Figure 18: Specimen placed in clamping device with a bonding mold insert
Figure 19: Adding two increments of composite resin
Figure 20: Light curing immediately on top of the mold

18
The specimens were then removed from the clamping device, first by loosening the
thumb nuts then holding the cured composite with a composite instrument while lifting up the
top of the clamp (Figure 21). The specimens were then stored in distilled water at 37 °C for 24
h
(75)
.

Figure 21: Final samples after bonding procedure

Table 2: Composition of material
Adhesive system
(80)
Scotchbond Universal (3M ESPE, St.Paul, MN, USA) (Lot #91129A)
(2021-10-31)
Composition Conditioner MDP Phosphate Monomer
Primer HEMA, Polyalkenoic acid copolymer, Water
Adhesive Dimethacrylate resins, Nanofillers, Initiators,
Ethanol
Others Silane
Dental Cleaner
(78)
KATANA Cleaner (Kuraray Noritake, Okayama, Japan) (Lot # C90003)
(2022-11-30)
Composition Water, 10-Methacryloyloxydecyl dihydrogen phosphate (MDP),
Triethanolamine, Polyethylene glycol, Stabilizer, Dyes
Composite Resin
(81)
IPS Empress Direct A1E, Ivoclar Vivadent, Amherst, NY , USA (Lot #
V32329, V36474) (2020-10-22)
Composition Monomer (20-21.5 wt%) Dimetharylates
Fillers (75-79 wt%)
40 nm- 3 μm
Barium glass, Ytterbium trifluoride, Mixed
oxide, Silicon dioxide, Copolymer
Others Additives, Initiators, Stabilizers, Pigments

19
Artificial aging
Twenty specimens from each group were tested for shear bond strength after 24 h of
storage in distilled water without simulated aging.
The remaining 20 specimens per group were subjected to artificial aging by thermal
cycling (Thermocycler THE-1100, SD Mechatronik, Westerham, Germany) with 20,000 cycles
at 5 °C and 55 °C with 15 s dwell time and 7 s transfer time
(76)
. After artificial aging, specimens
were kept in distilled water at 37 °C for 24 h until further testing.

Notch-edge shear bond strength testing
Shear bond strength (SBS) testing was performed using a universal testing machine
(Model 6596; Instron, Norwood, MA, USA) (Figure 22) at a crosshead speed of 1 mm/min
(75)
.
SBS testing was performed under standard laboratory conditions. Excess water on each specimen
was carefully blotted dry using a paper towel (Multi-Fold Towels, Scott brand, Neenah, WI,
USA) without touching the cylinder or the adhesive interface. Cylinders were loaded in shear
configuration with a notch-edge blade (Notch-edge crosshead blade, Ultradent, South Jordan,
UT, USA) until failure (Figure 23,Figure 24). Maximum load at the time of failure was recorded
in the software (Bluehill 3, V3.04, Instron, Norwood, MA, USA). SBS values were recorded in
N and converted to MPa
(77)
. Specimens that de-bonded before testing or during thermal cycling
were counted as 0 MPa.

20

Figure 22: Universal testing machine
Model 6596; Instron, Norwood, MA, USA
Figure 23: Close up of machine with specimen placed in loading jig and semicircular notch-edge
loading blade
Loading jig (Ultradent loading jig Ultradent, South Jordan, UT, USA)
Notch-edge loading blade (Notch-edge crosshead blade, Ultradent, South Jordan, UT, USA)
Figure 24: Bonded specimen placed in loading jig
Loading jig (Ultradent loading jig Ultradent, South Jordan, UT, USA)

Failure mode
Mode of failure was assessed with a stereo microscope (Wild M7; Wild Herrbrugg AG,
Heerbrugg, Switzerland) at x60 to x200 magnification
(77)
. Failure was classified as “adhesive at
dentin”, “cohesive in dentin”, “cohesive in composite”, or “mixed”.

Ultrastructural evaluation
Six additional intact human extracted molars were selected for scanning electron
microscopy (SEM) evaluation of the treated tooth surface (Table 3). Teeth were sectioned
parallel to the occlusal surface 2.5 mm below the cusp tips to expose mid-dentin and then
sectioned again in the same direction to obtain a disk with 1 mm thickness by using a precision
sectioning saw (IsoMet 1000; Buehler, Lake Buff, IL, USA) with a diamond blade (102 mm

21
dimension, 0.3 mm thickness; IsoMet Blade 15LC) at a speed of 800 RPM. Each slice was kept
in distilled water for 24 hours. Then, the dentin surface towards the pulp was marked with “X”
using a 1.0 mm diameter round diamond bur (#801.31.010 FG Medium Round Diamond) with
an electric hand piece. The smear layer was created with silicon carbide grinding paper
(CarbiMet Abrasive Sheet, 600, SiC, Buehler) under distilled water for 60 s
(37)
. Then, the surface
was rinsed with distilled water for 30 s,

and air dried at a distance of 20 mm from the surface for
5 s.
Dentin surface treatment was completed first, then processed for SEM analysis
(82)
. All the
surface treatment was done using exactly the same the protocol. The first specimen (K) (Table 3)
was treated with the tooth cleaner only (Katana Cleaner, Kuraray Noritake, Okayama, Japan)
with rubbing motion for 15 s, then rinsed for 10 s, and dried for 5 s at a distance of 10 mm. The
second specimen (SU) was treated with a universal bonding agent (Scotchbond Unviersal, 3M,
St. Paul, MN) for 20 s rubbing motion, then air thinned for 5 s at a 10 mm distance. The treated
surface was washed with 99% acetone (Alfa Aesar by thermo Fisher Scientific, Tewksbury, MA,
USA) for 60 s, then rinsed with distilled water for 60 s. The third specimen (K+SU) (Table 3)
was treated with the tooth cleaner, followed by the universal bonding agent. The remaining
specimens were first contaminated with saliva for 60 s, rinsed with distilled water for 15 s, then
dried for 5 s at a distance of 20 mm. The fourth specimen (C+K) (Table 3) was then treated with
a tooth cleaner, the fifth specimen was treated with a universal bonding agent (C+SU) (Table 3),
and the sixth specimen was treated with the tooth cleaner followed by the universal bonding
agent (C+K+SU) (Table 3). Saliva collection, contamination, and surface treatment were done
within the same day and was performed in the same way as for the SBS specimens. As soon as

22
each specimen was treated, they were kept in a 2.5% formaldehyde glutaraldehyde solution
(Electron Microscopy Sciences, Hatfield, PA, USA) for 24 hours at 4℃.
Table 3: Sample preparation for FeSEM
Groups C K SU SU+K C+K C+SU SU+C+K
Smear Layer Y
Saliva
Contamination
(C)
Y N Y
Katana Cleaner
(K)
N Y N Y Y N Y
Scotchbond
Universal (SU)
N N Y N N Y Y
Acetone Rinse N N Y N Y
Water Rinse N N Y N Y
4 ℃ 24 h storage in Formaldehyde Glutaraldehyde
Y:Yes N:No

After 24 hours, specimens were rinsed with 0.2 M sodium cacodylate buffer (Electron
Microscopy Sciences, Hatfield, PA, USA) at pH 7.4 for 1 h for three periods, followed by a
distilled water rinse for 1 min. The specimens were then dehydrated in ascending concentrations
of ethanol (25% for 20 min, 50% for 20 min, 75% for 20 min, 95% for 30 min, and 100% for 60
min). Subsequently, the specimens were immersed in hexamethyldisilazane (Electron
Microscopy Sciences, Hatfield, PA, USA) for 10 min and then placed on a filter paper inside a
covered glass vial and air-dried at room temperature inside a fume hood for 12 h. The dried
specimens were mounted on aluminum stubs and sputter-coated with gold/palladium. Images of
specimens were obtained using a field-emission scanning electron microscope (FEI Nova
NanoSEM, FEI Company, Hillsboro, OR, USA) at an accelerating voltage of 8.0-10 kV and
magnification of 1,000 to 20,000x (Figure 25).

23

Figure 25: Sample preparation for FeSEM (Workflow)
Statistical analysis
Statistical analysis of the obtained SBS data was performed with a 3-way ANOV A for the
factors; contamination, cleaning agent, and aging. To compare the different groups with each
other, a 1-way ANOV A with Bonferroni post-hoc test was performed utilizing SPSS software
(version 19.0, IBM, Armonk, NY , USA). The overall significance level was set to α=.05.
Failure modes were calculated as percentage per group.

24
Results
Notch-edge shear bond strength analysis
Mean notched shear bond strength values are displayed in Table 4 and Figure 26. The
overall descriptive statistic for shear bond strength test is shown by groups (Table 5). The results
reveal the highest mean of shear bonding strength recorded for group SU+A (16.98 ± 6.53 MPa);
this group had N = 19 with values ranging from 4.04 to 23.19 MPa. The next highest was the
group K+SU+A (15.93 ± 7.62 MPa), which had N = 18 and values ranging from 4.63 to 30.84
MPa. The control group SU (14.38 ± 7.43 MPa) had N = 18 and values ranging from 1.14 to
23.44 MPa. The fourth highest mean was C+SU (13.51 ± 9.03 MPa), with N = 16 and values
ranging from 1.79 to 30.51MPa. The lowest mean of shear bonding strength was C+SU+A (9.69
± 6.03MPa), which had N = 20 and values ranging from 2.55 to 21.87 MPa. The second lowest
was C+K+SU (11.04 ± 6.63 MPa), which had N = 19 and values ranging from 1.35 to 25.12
MPa. Third lowest was K+C+SU+A (11.81 ± 6.75 MPa), which had N = 22 and values ranging
from 1.23 to 29.76 MPa. Fourth lowest was K+SU (13.11 ± 5.34 MPa), with values ranging from
3.92 to 24.59 MPa.
Table 4: Notch-edge shear bond strength in MPa ± SD
Artificial
aging
No surface
treatment
Katana
Cleaner
Saliva
Contamination
Saliva Contamination
and Katana Cleaner
Not aged
SU
14.38±7.43
K+SU
13.11±5.34
C+SU
13.51±9.03
C+K+SU
11.04±6.63
Aged
SU+A
16.98±6.53*
K+SU+A
15.93±7.62
C+SU+A
9.69±6.03*
C+K+SU+A
11.81±6.75
* values are significantly different from each other (p<0.05)

25
Table 5: Descriptive statistics for shear bond strength by group
Intervention N
Mean
(MPa)
Std.
Deviation
Std.
Error
95% Confidence
Interval for Mean
Minimum Maximum
Lower
Bound
Upper
Bound
SU (Control) 18 14.38 7.43 1.75 10.68 18.07 1.14 23.44
SU+A 19 16.98 6.53 1.50 13.84 20.12 4.04 23.19
C+SU 16 13.51 9.03 2.26 8.70 18.32 1.79 30.51
C+SU+A 20 9.69 6.03 1.35 6.87 12.51 2.55 21.87
K+SU 19 13.11 5.34 1.22 10.54 15.69 3.92 24.59
K+SU+A 18 15.93 7.62 1.80 12.14 19.72 4.63 30.84
C+K+SU 19 11.04 6.63 1.52 7.86 14.24 1.35 25.12
C+K SU+A 22 11.81 6.75 1.44 8.81 14.80 1.23 28.76

Figure 26: Notch-edge shear bond strength (MPa) by groups

26
The Kolmogorov-Smirnov test showed that the overall data was normally distributed
(p=0.46096). The homogeneity of variances assumption was checked using the Levene’s test,
which found the assumption to be met (F = 1.149, df1 = 7, df2 = 143, p = 0.336) (Table 6).
Therefore, a 3-way ANOV A was performed with the three factors: 1. contamination, 2. cleaner,
and 3. aging (Table 7). Furthermore, a 1-way ANOV A with Bonferroni post-hoc comparison was
used to compare data between the different groups (Table 8).
Table 6: Test of homogeneity of variance
Shear Bond Strength (MPa)
Levene Statistic df1 df2 Sig.

Based on mean 1.149 7 143 0.336
Based on median 0.973 7 143 0.453
Based on median and with adjusted df 0.973 7 137.2 0.453
Based on trimmed mean 1.166 7 143 0.326

Based on tests of between-subject effects, the only significant factor influencing shear
bond strength was contamination (p=0.002). All other interventions and interactions were
insignificant (p>0.05) (Table 7).
Table 7: Tests of between-subject effects on shear bond strength for three-way ANOV A
Source
Type III Sum
of Squares
df
Mean
Square
F Sig.
Contamination 482.36 1 482.36 10.05 0.002*
Cleaning 16.62 1 16.62 0.35 0.557
Aging 13.04 1 13.04 0.27 0.603
Contamination/Cleaning 9.03 1 9.03 0.19 0.665
Contamination/Aging 168.3 1 168.3 3.51 0.063
Cleaning/Aging 54.12 1 54.12 1.13 0.29
Contamination/Cleaning/Aging 44.71 1 44.71 0.93 0.336
Note. R Squared = 0.106 (Adjusted R Squared = 0.062)

27
According to the test of between-subject effects (Table 8), the one-way ANOV A showed a
significant difference between groups; however, based on the Bonferroni comparison this was
significant only between groups SU+A and C+SU+A (p=0.036). All other groups were not
significantly different from each other (p>0.05) (Table 7).
Table 8: Tests of between-subject effects on shear bond strength for one-way ANOV A
SBS (MPa)
Sum of Squares df Mean Square F Sig.
Between Groups 809.873 7 115.696 2.411 .023
Within Groups 6862.959 143 47.993
Total 7672.833 150

Failure analysis
The “adhesive at dentin” failure was the most commonly observed failure mode (63.3%),
followed by the “mixed” (34.4%). Only a small percentage of “cohesive in composite” (2.4%)
failures were observed, however, there was no failure at “cohesive in dentin” (Figure 27).

Figure 27: Overall failure mode analysis by failure type

63.3
2.4
34.3
0
10
20
30
40
50
60
70
80
90
100
Adhesive at dentin Cohesive in
composite
Mixed
Percent

28
A higher frequency of “adhesive at dentin” failures (n=17) were seen in the K+SU group,
followed by C+SU+A (15) and C+K+SU+A (15), with the lowest frequency in K+SU+A (10).
The frequency of cohesive in composite failures were markedly lower for K+SU (2), C+SU+A
(1), and C+K+SU (1). For the “mixed” mode, failures were observed most frequently in the
SU+A (11) group, the K+SU+A (10) group, and the C+K+SU+A (8) group, while failure was
least frequent with the K+SU (80) group (Figure 28).

Figure 28: Failure mode analysis in absolute numbers by groups

The majority of failures for each of the groups was observed in the “adhesive at dentin”
mode, with the exception of SU+A and K+SU+A where roughly 50% of the failures were also
the result of the “mixed” mode. “Cohesive in composite” mode comprised a small percentage of
the failure in C+SU, C+SU+A, and C+K+SU (Figure 29).

29

Figure 29: Failure mode analysis in percentage by groups

Ultrastructural evaluation
The application of 10-MPD containing cleaner (Katana Cleaner, Kuraray, pH = 4.5) alone
was unable to remove the smear layer. Dentin tubules were fully blocked by smear plugs and
negligible exposure of intertubular collagen network was observed in some areas (Figure 30).
The application of an ultra-mild universal adhesive (Scotchbond Universal, 3M ESPE,
pH = 2.7) alone to dentin using self-etching was unable to completely remove the smear layer.
Dentin tubules were mostly blocked by smear plugs; however, the intertubular collagen network
was partially exposed (Figure 31). The application of 10-MPD containing cleaner (Katana
Cleaner, Kuraray, pH = 4.5) followed by the application of the ultra-mild universal adhesive (pH
2.7) resulted in modification of the smear layer. Intense exposure of the intertubular collagen
network was observed while dentin tubules remained blocked by the smear layer (Figure 32)
revealing the presence of smear plugs. The application of two different acidic solutions of
different pH resulted in enhanced etching effect and decalcification of the hydroxyapatite at the
intertubular dentin.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Adhesive at dentin Cohesive in composite Mixed

30

Comparison of FeSEM images among Non-Contaminated groups
Figure 30: FeSEM-K
Field-emission scanning electron microscopy (FeSEM) showing dentin surface after application
of MPD-containing cleaner (Katana Cleaner, Kuraray) (magnificationX2,000). Black arrows indicate
smear plugs. No smear plugs were removed, and the smear layer still exists.
Figure 31: FeSEM-SU
FeSEM showing decalcification of the dentin after application of an ultra-mild universal adhesive
(Scotchbond Universal, 3M ESPE) (magnification X2,000). Black arrows indicate smear plugs and red
arrows indicate removed smear plugs (dentinal tubules exposure). Smear layer is partially removed.
Figure 32: FeSEM-K+SU
FeSEM showing decalcification of the dentin after application of the MPD-containing cleaner
(Katana Cleaner, Kuraray) followed by an ultra-mild universal adhesive (Scotchbond Universal, 3M
ESPE) (magnification X2,000). Slight exposure of the intertubular collagen network was observed while
dentin tubules remained blocked by smear plugs (black arrows), and more opening of dentinal tubules
(red arrow).

Contamination with saliva followed by the application of the 10-MPD containing cleaner
(Figure 33), the universal adhesive (Figure 34), or a combination of both (Figure 35) has shown
an increase in the intertubular collagen network with dentin tubules blocked by smear layer
(Figure 33, Figure 34) or smear plugs (Figure 34, Figure 35). The pH of the tested saliva ranged
from 6.4 to 6.6. Saliva contamination for 60 s modified the dentin smear layer and increased
intertubular decalcification. Conversely, no bacterial contamination was observed in all
contaminated specimens (Figure 33, Figure 34, Figure 35).

31

Comparison of FeSEM among Contaminated groups
Figure 33: FeSEM-C+K
FeSEM showing dentin surface after saliva contamination for 60s followed by the application of
MPD-containing cleaner for 20 s (Katana Cleaner, Kuraray) (magnification X2,000). Black arrows
indicate smear plugs. Smear plugs were partially removed (red arrows), and smear layer still exists,
however, with an increase in intertubular dentin collagen fiber exposure.
Figure 34: FeSEM-C+SU
FeSEM showing decalcification of the dentin after saliva contamination followed by the
application of an ultra-mild universal adhesive (Scotchbond Universal, 3M ESPE) (magnification
X2,000). Black arrows indicate smear plugs. Smear plugs and smear layer were partially removed (red
arrows), however, with more decalcification of the intertubular dentin collagen network.
Figure 35: FeSEM-C+K+SU
FeSEM showing decalcification of the dentin after saliva contamination followed by the
application of the MPD-containing cleaner (Katana Cleaner, Kuraray) followed by an ultra-mild universal
adhesive (Scotchbond Universal, 3M ESPE) (magnification X2,000). Black arrows indicate smear plugs.
Smear plugs were partially removed (red arrows), and smear layer mostly removed, with an extensive
decalcification of the intertubular dentin collagen network.

32
Discussion
The purpose of the present in vitro study was to evaluate the effect of a 10-MDP tooth
cleaning agent on the dentin bond strength of a universal adhesive system used in self-etch mode
to saliva-contaminated dentin. To the best of the authors’ knowledge, so far there is no published
data about research on this topic using this type of tooth cleaner.
The results showed that contamination is the only factor that caused significant differences
in the results. Therefore, the 1
st
null hypothesis that there is no difference after saliva
contamination with SU to dentin was rejected. However, there was no difference in bond
strength using a 10-MDP-containing dental cleaning agent, and artificial aging did not influence
the bond strength of contamination or cleaning agent, therefore, the 2
nd
and 3
rd
null hypothesis
were accepted.

Verification of using a universal adhesive system in self-etch mode
A universal adhesive system applied in self-etch (SE) mode was chosen for this study. The
SE approach is advantageous in minimizing the bonding steps and facilitating the clinical
application
(83)
.

The methacrylate monomers modified with acidic functionalities in these adhesive
systems can demineralize and infiltrate the dentin simultaneously, resulting in fewer steps, thus
making it easier to standardize the samples and avoiding technical errors during handling
(84)
. In
addition, the mild acidity of the monomer is capable of achieving a more uniform thickness of
the hybrid layer due to their ability to avoid excessive demineralization of the collagen network
in dentin
(41, 85, 86)
. Furthermore, 10-MDP containing universal adhesive systems can form
chemical bonds between the phosphate end of the acidic monomer and the remaining Ca
2+
ions
from the hydroxyapatite (HAp) of the dentin
(19, 87, 88)
. As a result, it can achieve sufficient bond

33
strength without removing the smear layer completely and it is less invasive to the dentin-pulp
complex
(89)
.
Compared to the etch-and-rinse mode, SE adhesive systems avoid the use of strong acidic
etching solutions, making it possible to prevent over etching dentin and the increase of fluid flow
from the pulp towards the dentin surface during the bonding procedure
(90)
. Therefore, using the
SE mode is recommended for dentin bonding to achieve adhesion to various heterogeneous
restorative substrates
(5, 91)
.

Longevity of 10-MDP containing universal adhesive agent in SE mode
When comparing the obtained data, the following facts were found: Artificial aging did not
cause any significant change in bond strength for Group SU (Control) and SU+A (Control aged).
Munoz et al
(92)
,

stated that universal adhesives with 10-MDP appear to maintain the bond
strength after artificial aging in water compared to other universal adhesives without 10-MDP.

The cause for this outcome could be the creation of impermeable and stable 10-MDP-Ca salts,
formed by the interaction of 10-MDP and the Ca
2+
of hydroxyapatite
(19, 21, 22, 27, 29, 30, 93, 94)
.
Using the same treatment protocol, axially sectioned SEM images showed an average depth
of resin tags of about 1 μm with SU
(71)
. This depth was significantly shorter than compared to
other adhesive systems that were tested in the study, however, it still showed sufficient bond
strength
(71)
. The authors concluded that the bond strength of SU results mainly from chemical
adhesion rather than from micro-mechanical interlocking
(27, 30, 31, 71, 94)
. Furthermore, in addition
to 10-MDP, SU contains a polyalkenoic acid copolymer as one of its components
(80)
.
Polyalkenoic acid contains multiple carboxyl functional groups attached to polymers; it can be
found in glass-ionomers which therefore adheres to HAp chemically as well
(95)
. The main

34
difference between 10-MDP and polyalkenoic acid is that 10-MDP contains specific monomers
which can be linked to HAp and polymerize
(95)
. Therefore, the partial demineralization of dentin,
the chemical bonding to HAp, and the creation of nanolayers by 10-MDP, all contribute to long-
term bond strength of the universal adhesive systems to the dentin surface.

However, another study using SBS testing after artificial aging by water storage for 24 h, 3
months, and 1 year showed that the SU group exhibited significantly lower bond strength after
one year when compared to 24 h or three months of water storage
(96)
. Hence, this study suggests
that longer periods of aging or different types of aging methods might change the long-term
result of the SU bond strength.

Contamination
Next, it was observed that group SU and C+SU did not differ significantly (p>0.05) from
each other, but groups SU+A and SU+C+A were significantly different from each other
(p<0.05). Therefore, it is suggested that saliva contamination does not affect immediate bonding
strength of SU, but saliva contamination affected the long-term bond strength.
SU contains a monofunctional water-soluble monomer, HEMA. HEMA increases the
affinity of two heterogenous substances, the hydrophilic tooth structure and the hydrophobic
components of the adhesive. This improves the penetration of the adhesive into dentin and
subsequently helps to create a more homogenous interface
(28)
. It was suggested that one-step self-
etch adhesive systems might be less negatively affected by contamination because of the
presence of the water-based primer, HEMA. The hydrophilicity of HEMA will improve diffusion
and passing through the contaminants, thus, allowing subsequent penetration into the structure
(5,
8, 63)
.

35
In order to effectively remove saliva from bonding surfaces, water rinsing for a duration of
at least 30 s was suggested
(97)
. Conversely, it was reported that water rinsing was not capable of
removing saliva from etched tooth surfaces regardless of the contaminant exposure time
(98)
. In
the present study, the contaminated tooth surface was cleaned by rinsing with distilled water for
15 s
(77)
. Therefore, some elements of saliva might have remained on the tooth surface upon
bonding. However, a recent study has shown that no significant difference was observed in bond
strength using 10-MDP containing universal adhesive system in SE mode after contamination of
saliva
(99)
, while another study reported nanoleakage already after 24 h of bonding to saliva
contaminated teeth
(45)
. Therefore, it is suggested that water degradation and monomer leaching
from saliva contaminated bonding interfaces might possibly occur, affecting the longevity of
bonded restorations
(71, 99, 100)
. Dentin permeability decreases by 65% upon saliva contamination
due to adsorption of salivary glycoproteins into dentinal tubules
(44, 100)
. The affinity of
glycoproteins with calcium might create a hybrid layer consisting of hydrophilic monomers and
proteinic complexes surrounding exposed collagen in dentin
(101)
. These large organic molecules
can create micro gaps in the hybrid layer
(50)
. The competing interaction of the glycoproteins with
Ca
2+
from HAp might have interfered with the interaction of the 10-MDP molecules in SU.
Another inhibiting factor could be the presence of sodium ions, which can consume 10-
MDP by forming 10-MDP-Na, which easily dissolves in water
(102)
. With Na
+
as one of the main
ions in saliva, saliva contamination could lead to some of 10-MDP reacting with Na
+
rather than
Ca
2+
, thus leading to hydrolysis instead of nanolayer formation. The same study hypothesized
that 10-MDP-Na can negatively affect immediate and even more long-term bond strength
(103)
.
As mentioned before, the universal adhesive system used in this study, SU, contains
HEMA which interferes with the formation of the nanolayer
(80, 103)
. Therefore, it is suggested that

36
saliva contaminated dentin surface formed inadequate or possibly no nanolayer to be able to
withstand thermal cycling. Therefore, immediate bond strength showed no significant difference,
however, long-term bond strength showed a significant decrease.
Moreover, SU is an ultra-mild (pH 2.7) adhesive containing ethanol as a solvent instead of
acetone
(80)
. Compared to acetone, ethanol has a lower vapor pressure, meaning that the
evaporation of the solvent will take longer compared to acetone-based adhesives. This makes it
more susceptible for retention of water if the application time and application with agitation are
not properly executed
(89, 104-107)
. It is clear that if bonding complications occur due to saliva
contamination, it will affect bond strength as both adhesive agents and the application technique
are very sensitive to errors. It might not appear in immediate bond strength as hydrolysis and
breakdown takes time, however, it will become obvious with time.

Cleaning agent
From the results of immediate bonding strength (Table 7) it can be seen that groups SU and
K+SU did not have a significant difference. Therefore, it can be said the tooth cleaner did not
affect the immediate bonding strength of SU. Similarly, when comparing group SU+A and
SU+K+A, there was no significant difference. Therefore, the tooth cleaner also did not affect
long-term bonding strength.
From the SEM result, it was found that using both agents together, K and SU (Figure 32),
more decalcification of HAp, smear layer modification and intense exposure of intertubular
collagen were observed. This might have happened because of the application of two different
acidic agents. However, according to SBS testing from this study, this ultrastructural change did
not appear to cause changes in mechanical property.

37
The Katana tooth cleaner contains 10-MDP as the active ingredient at an ultra-mild pH of
4.5 and it is very close to the dentin buffering capacity of pH 5.4-5.9
(108)
. Therefore, it can be
speculated that pH of dentin might have been able to come back to the higher pH after
application of cleaner. One study reported that when applying SE primer of pH 2.0, the dentin
surface was reduced from pH 6.9 to 5.4
(36)
, however, SU is pH 2.7, therefore, it is suggested that
the dentin surface pH was maintained higher than pH 5.4 in both cases. Considering critical pH
of dentin is 6.5
(109)
, it could alter surface morphology of dentin, however, very minimally. SEM
showed that the tooth cleaner alone (Figure 30) showed slight intertubular dentin collagen
network exposure, SU alone showed more prominent exposure (Figure 31), while using both
agents showed deeper exposure (Figure 32). This was because of the difference in pH of the
agents, and application. However, due to the much milder acidity (pH 4.5) of the tooth cleaner
and primer (pH 2.7), degradation of collagen network or removal of smear layer did not happen.
K and SU together still did not alter the bonding surface. Therefore, it is suggested that
application of K and SU should affect the formation of the hybrid layer negatively.
To support this, another factor is that these groups did not have saliva contamination;
therefore, the surface was covered mainly with debris from the smear layer creation process. A
previous study has reported that the shear bond strengths of the all-in-one self-etch adhesives
were not affected by smear layer thickness
(110)
.

The result from this study shows higher
maximum shear bond strength in groups K+SU and K+SU+A compared to SU and SU+A, but
the mean value was slightly lower than the latter. In addition, fracture mode also had similar
results. This may be because of an extra step of mechanical surface cleaning and water rinsing
which helped remove smear layer without damaging the tooth surface, thus, yielded a cleaner
surface. As a result, this led to higher bond strength in some specimens but not all due to a

38
different dentin surface condition. From the SEM result, it was confirmed that tooth cleaner was
unable to remove smear layer or smear plug. Slight exposure of the intrertubular collagen
network shows that this tooth cleaner does not decalcify or damage the dentin collagen.
Therefore, it can be said that the tooth cleaner did not interact negatively or interfere with the
chemical interaction of SU to the tooth surface.
From the obtained results, it can be said that 10-MDP containing tooth cleaner used in this
study is safe to use on dentin surface. The manufacturer’s instruction regarding water rinsing
time, “until the color disappears,” was valid in this study and 10 s was sufficient. In addition, it is
suggested that immediate bond strength did not improve due to incomplete smear layer removal
by the tooth cleaner. Its pH is very mild, therefore, even after application of SU, the collagen
network of the dentin surface was not negatively altered. Therefore, no significant change in the
SBS result was found with or without using the tooth cleaner in both aged and non-aged group.

Contamination and cleaning agent
When comparing groups SU, C+SU and C+K+SU, no significant difference was found.
Therefore, it was confirmed that the saliva contamination, tooth cleaner itself, and combination
of both did not affect immediate bond strength of SU. The adhesive was able to chemically bond
to the tooth despite saliva contamination; this effect was not affected by the tooth cleaner.
When comparing groups SU+A, C+SU+A, and C+K+SU+A, no significant difference was
found. Therefore, after aging, application of tooth cleaner did not have any influence on bond
strength of the contaminated tooth. It is suggested that after application of the tooth cleaner, 10-
MDP in SU was able to form 10-MDP-Ca layer, and this might be because there was
no significant difference in the bond strength between SU+A and C+K+SU+A.

39
From the SEM images, all the saliva contaminated teeth images (Figure 33, Figure 34,
Figure 35) indicated more demineralization and increased intertubular collagen network
exposure. Because the saliva pH was around 6.4-6.6, which is around critical pH of
decalcification of dentin,

saliva might not have contributed to cause of decalcification
(108)
.
However, for Figure 33, saliva protein might have interacted with loose Ca
2+
from HAp in
intertubular dentin (Figure 36, Figure 37), then the tooth cleaner was able to remove both saliva
protein with Ca
2+
together after rinsing (Figure 38, Figure 39), and partially removed the smear
layer as well (Figure 40). For Figure 35, the same process occurred; however, the acidity of SU
enhanced the etching effect of the functional monomer due to less saliva protein and loose Ca
2+
found in its surrounding, and adhesive agent was able to penetrate more effectively (Figure 41,
Figure 42).

Contaminated tooth surface
Figure 36: Dentin surface contaminated by saliva
Figure 37: Saliva protein adhering to loose calcium ion in smear layer

40

Contaminated tooth surface with cleaner
Figure 38: Application of 10-MDP containing cleaner
Figure 39: Rinsing with water
Figure 40: Saliva protein and adhered loose calcium ion washed away after rinsing

Adhesive process
Figure 41: Adhesive agent application
Figure 42: Penetration of adhesive agent

Since the surface is cleaner without physical blockage from saliva proteins or Ca
2+

blocking the surface, the adhesive agent was able to infiltrate more into the dentin.
Lastly, Figure 34 reveals blocked dentinal tubules by smear layer and smear plugs.
Because with the absence of the tooth cleaner application step, organic contaminants (saliva
proteins) and inorganic debris (Ca
2+
, K
+
, PO4
3-
, Cl
-
)

remained on the surface (Figure 43). The
rubbing motion of SU was effective enough to etch the surface, and perhaps saliva protein may

41
have helped gather loose Ca
2+
together to make more space for the adhesive material to infiltrate
deeper (Figure 44). As a result, the functional monomer of SU was able to etch solid HAp at the
inner surface (Figure 45, Figure 46). This could be the reason because more modification on
intertubular dentin was seen in comparison to the non-contaminated specimen (SU alone).

Contaminated tooth surface
Figure 43: Dentin surface contaminated by saliva
Figure 44: Salivary protein aggregating loose calcium ion creating spaces

Application of adhesive agent on contaminated tooth surface
Figure 45: Adhesive application
Figure 46: Adhesive agent penetration
Adhesive agent penetrating into dentin because of the space created by salivary protein.

42
From this study, in a clinical situation when saliva contamination occurs on the dentin
surface, 10-MDP containing tooth cleaner in combination with an ultra-mild pH adhesive system
can be used as it did not influence the bond strength, neither negatively nor positively.
None of the SEM images of saliva contaminated samples have shown bacteria. It is
suggested that K and SU were effective enough to remove organic contaminant. However, it
could be assumed that there were no bacteria present at the sample preparation.

Other factors possibly contributing to bond strength
The agitating motion during application is also crucial when applying SU. As such, proper
application steps and mode must be followed in order to obtain a favorable bond surface and
result.

In the universal adhesive system, the application mode and coating could be the key to
successful bonding.

The mode of application, for example, with or without rubbing motion on the
bonding dentin surface, is likely to make a difference in monomer penetration into the smear
layer and dentin
(89, 111)
. Without any agitation, adhesives will diffuse into the thick smear layers
and create a thin hybrid layer, and the acidic monomer might not sufficiently penetrate into
dentin
(111, 112)
. Also, the solvent of adhesive agent will not evaporate, therefore, there might be
excess of solvent trapped in hybrid layer
(104, 113)
. On the other hand, with a continuous rubbing
motion, the acidic monomer will penetrate into the smear layer, react with HAp and decrease its
pH by acid-base reaction. As a result, better adhesive polymerization, no further acid etching,
and nanolayer creation will be expected
(86, 107, 113, 114)
.
The rubbing application was required by the manufacturer for the tooth cleaner. The mode
of application might have helped the interaction with glycoprotein and 10-MDP micelle to be

43
washed away. This cascade made it possible to achieve a cleaner surface, and for the adhesive
agent to infiltrate more into the tooth.
In this way, hydrolysis of adhesive layer or gap formation could be avoided, and this could
be the reason why the aged groups did not have significant difference compared with the non-
aged groups.

Study Limitations
The present in vitro study experienced limitations regarding study setting, testing method,
and material. Limitations of the study setting were that due to the in-vitro nature of the study; the
results cannot be readily generalized to clinical settings. The quality of dentin bonding surfaces
is critical to when testing bonding strength
(99)
. According to the ISO technical specification
11405,

it is recommended to measure the dentin bond strength immediately after extraction
(115)
.
However, this is not always practical. Hence, teeth within one month after the extraction but no
longer than after six months should be used to standardize the samples, considering the
biological change occurs during the initial days to several weeks after extraction. In addition, it is
recommended to store teeth in refrigerated (about 4℃) conditions in distilled water and to
change the water frequently until further testing to avoid any additional detrimental changes of
the bonding surface. However, in this study, teeth used were more than six months after
extraction and stored in the distilled water at room temperature. After sample preparations
started, specimens were kept in distilled water at 37 ℃. This is far different from an intraoral
environment. For standardization purposes, all samples were kept in the same conditions
throughout this study.

44
In addition, under clinical conditions dentin is a living tissue. During tooth preparation
without sufficient anesthesia, intrapulpal fluid can flow towards the bonding surface
(116)
.

However, in this study, since extracted teeth were used, only the hydrolysis effect from the outer
environment was tested, and inner cause of hydrolysis was not taken into consideration. This
could cause differences in results when comparing in vivo and vitro studies. Therefore, in vivo
tests are needed to validate the true effect of the tooth cleaner.
Comparing different studies with each other is very difficult when dentin bonding is
performed
(117)
. Adhesive materials used, mode of etching, bond strength testing method, tooth
substrate (human or bovine dentin), experience or skills of examiner, or storage medium can
highly influence the result
(99, 117-119)

For the testing method, adhesive application might have caused the limitation in bond
strength. It is suggested to apply more than one coat of the adhesive material
(120)
. Evaporation of
the solvent can result in a very thin adhesive layer which could become a problem when the
oxygen inhibited layer interferes with the polymerization of the adhesive layer
(23, 89, 121)
.

In the
present study, one coat of SU was applied, followed by air drying until a very thin uniformed
layer was observed. Some of the samples had very low shear bond strength, and a few of the
samples even failed during thermal cycling. This might be because an oxygen inhibited layer was
created during air blow, which may have formed an incomplete polymerized adhesive layer. As a
result, bond strength was already weakened. Application mode or coating could be deferent
among which adhesive systems were used. Therefore, when comparing to different studies, the
employed adhesive system and its methodology must be well documented.
Another factor is limitation in artificial aging. Thermal cycling is one of the most
commonly used artificial aging methods. It has been suggested by the International Organization

45
for Standardization (ISO) that a minimum of 500 cycles should be performed in distilled water
with the temperature between 5°C and 55°C and a dwell time of 20 s
(115)
. In this study, 20,000
cycles were performed for the aged groups, therefore, the amount of aging was sufficient.
However, this regime would not adequately simulate the degradation occurring in a clinical
situation
(122)
. Other factors influencing the impact of thermal cycling are water temperature, the
dwell time, and the lack of securing samples when aging, which can allow movement of the
specimens in the water bath, possibly causing accidental mechanical force on the bonded
samples
(122, 123)
. Nevertheless, thermal cycling can also cause fatigue of the adhesive-resin
interface by volumetric changes triggered by the alternating temperature, which can mimic the
intraoral environment. Another method of aging can be water storage
(99, 123)
. Many studies have
performed ISO recommended long-term storage of six months or longer to observe static fatigue
of the adhesive layer
(115)
. The method of water storage might be easier to compare with other
studies as it usually does not involve too many valuables other than aging solutions, storage
duration, and temperature
(123)
. Therefore, even if there were some existing limitations, the aging
regimen used in this study was valid.
Additionally, the technique sensitivity of the bonding system is another factor of the
limitation. Bonding is a technique-sensitive matter regardless of the mode of the system and
several parameters like air dry method and time, adhesive application mode and time, and the
experience of the examiner can influence final results
(89, 99)
. Testing methods can have a great
impact on the results as well. According to Van Meerbeek et al
(124)
,

excess of adhesive agent
applied to non-bonded surfaces will modify the results of shear bond strength tests. Distribution
of the force applied to the shear bond strength test is never uniform due to the force applied only
from one side or area, and this causes less accuracy of the result compared to micro-tensile

46
testing
(125, 126)
.

To increase the accuracy of testing, one of the most important factors of shear
bond testing is application of load exactly at the bonded interface to prevent the composite
cylinder from rotating or bending rather than a shear load
(127, 128)
. Therefore, the positioning of
the samples is very critical
(128)
. When comparing between knife edge blade and notched edge
blade, positioning of notched blade is much simpler and repeatable because the blade wraps the
composite
(129)
. Also, contact area of notched edge blade is much larger than that of the knife edge
blade, the positioning of the blade will be less critical, and yields less force concentration. As a
result, more distribution of shear force is expected
(128)
. Micro-tensile testing can apply the stress
more uniformly to the bonded interface, however, the sample preparation is quite challenging
and could cause cracks or defects on the specimen and failure could occur during preparation
(127)
.
On the other hand, macro-shear test is more examiner friendly. This suggests that using macro-
shear test with a notched edge blade in this study was acceptable. It is difficult to compare the
results in different studies with the actual bonding strength number obtained in each study,
however, trends of data can be compared
(124)
.
Lastly, the material also had limitations in this study. As only the SU adhesive system was
investigated, the results of the present study cannot be generalized to other universal adhesive
systems available in market. The cleaning agent did not cause any negative effects on bond
strength, this was maybe because both the cleaning agent and SU contain 10-MDP as a main
active ingredient. Obviously, other ingredients of the cleaning agent were chosen by the
manufacture that would not interfere with 10-MDP. However, other universal adhesive systems
contain different functional monomers, such as, GPDM, 4-META, 6-MHP, Phenyl-P,
MTEGP
(20)
. Further studies are needed to investigate the interaction of other functional
monomers with the cleaning agent.

47
The dentin samples also had its limitation. Even though all the discolored, caries affected,
or sclerotic dentin samples were discarded, it is difficult to standardize the dentin condition for
the testing. Differences in bond strength due to varying dentin depth can occur
(130)
. Since each
tooth is unique due to differences in anatomy such as height of cusps and pupal chamber, it is
challenging to slice the specimen at the same depth and similar quality.
A further parameter that has to be considered is the type of contamination. In this study, the
saliva of only one person was used as the contaminant and the results could vary based on the
oral hygiene, genetics, and physiology of the person providing saliva for the investigation.
This study showed the efficacy of 10-MDP containing cleaner (K) when applied on the
substrate before the application of 10-MDP containing ultra-mild universal adhesive agent, in
this case SU. In the past, 10% polyacrylic acid, 17% Ethylene diamine tetraacetic acid (EDTA),
or 37% phosphoric acids were commonly used to clean the dentin surfaces after contamination as
cleaning agent
(57, 63)
. However, phosphoric acid can over etched dentin and therefore decreased
bond strength with possible clinical complications
(131)
. Both polyacrylic acid and phosphoric acid
had increased the activity of collagenolytic enzymes, such as matrix metalloproteinases (MMPs)
and cysteine cathepsins, that could enhance degradation of hybrid layer
(5, 38, 113, 132)
. EDTA was
able to remove smear layer without altering the dentin collagen network, however, it is less
effective in removing organic contaminants
(57, 133)
.
For the 10-MDP containing cleaner, the acidity is too mild that it did not completely clean
smear layer; therefore, EDTA might be more efficient to remove inorganic debris if there is no
saliva contamination. However, the cleaner might have been able to remove organic components
of contamination from saliva without damaging the collagen network for infiltration of adhesive

48
agents. In addition, the cleaning mechanism does not use acid to demineralize the surface,
therefore, no activation of MMPs nor clinical complications to be expected.
From the results, it is concluded that SU or K separately do not show enough
demineralization, however both materials together ensure adequate demineralization of the
substrate without over etching surface, and K did not influence the bond strength. Therefore,
further studies are needed to confirm efficiency of 10-MDP containing cleaner when applied
before using some other universal adhesive agents with or without 10-MDP.

49
Conclusion
With the limitation of the study, it can be concluded:
• Saliva contamination does affect longevity of bond strength.
• Artificial aging through thermal cycling did not influence bond strength.
• 10-MPD containing cleaner did not affect bond strength. It did not damage the
dentin structure or completely remove the smear layer or plugs.
• However, its application of the 10-MDP containing cleaner followed by
application of SU did not influence adhesion.

There was a significant decrease in bond strength after saliva contamination in aged
specimens, therefore, the 1
st
null hypothesis was rejected. Neither artificial aging nor the
cleaning agent influenced the bond strength, therefore, the 2
nd
and 3
rd
hypotheses were accepted.

Only one universal adhesive was tested in this study. Other universal systems with or
without 10-MDP will need to be tested in order to evaluate the material interactions. Also, in
vivo studies are needed due to various intrinsic and extrinsic factors that cannot be completely
simulated with in vitro studies.

50
Conflict of interest
The author declares no conflict of interest.

51
IRB
IRB number: APP20-04357

52
Funding
The present research study was supported by the program of Advanced Operative and
Adhesive Dentistry, Restorative Sciences, at Herman Ostrow School of Dentistry of University
of Southern California.

53
References
1. Peters MC, McLean ME. Minimally invasive operative care. I. Minimal intervention and
concepts for minimally invasive cavity preparations. J Adhes Dent. 2001;3(1):7-16.
2. Murdoch-Kinch CA, McLean ME. Minimally invasive dentistry. J Am Dent Assoc.
2003;134(1):87-95.
3. Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to
enamel surfaces. J Dent Res. 1955;34(6):849-53.
4. Bowen RL. Adhesive Bonding of Various Materials to Hard Tooth Tissues. I. Method of
Determining Bond Strength. J Dent Res. 1965;44:690-5.
5. Van Meerbeek B, Yoshihara K, Van Landuyt K, Yoshida Y , Peumans M. From
Buonocore's Pioneering Acid-Etch Technique to Self-Adhering Restoratives. A Status
Perspective of Rapidly Advancing Dental Adhesive Technology. J Adhes Dent. 2020;22(1):7-34.
6. Bertolotti RL. Conditioning of the dentin substrate. Oper Dent. 1992;Suppl 5:131-6.
7. Nakabayashi N, Kojima K, Masuhara E. The promotion of adhesion by the infiltration of
monomers into tooth substrates. J Biomed Mater Res. 1982;16(3):265-73.
8. Van Meerbeek B, Peumans M, Verschueren M, Gladys S, Braem M, Lambrechts P, et al.
Clinical status of ten dentin adhesive systems. J Dent Res. 1994;73(11):1690-702.
9. Retief DH, Austin JC, Fatti LP. Pulpal response to phosphoric acid. J Oral Pathol.
1974;3(3):114-22.
10. Fusayama T, Nakamura M, Kurosaki N, Iwaku M. Non-pressure adhesion of a new
adhesive restorative resin. J Dent Res. 1979;58(4):1364-70.
11. Iwaku M, Nakamichi I, Nakamura K, Horie K, Suizu S, Fusayama T. Tags penetrating
dentin of a new adhesive resin. Bull Tokyo Med Dent Univ. 1981;28(2):45-51.

54
12. Manfroi FB, Marcondes ML, Somacal DC, Borges GA, Junior LH, Spohr AM. Bond
Strength of a Novel One Bottle Multi-mode Adhesive to Human Dentin After Six Months of
Storage. Open Dent J. 2016;10:268-77.
13. Van Meerbeek B, De Munck J, Yoshida Y , Inoue S, Vargas M, Vijay P, et al. Buonocore
memorial lecture. Adhesion to enamel and dentin: current status and future challenges. Oper
Dent. 2003;28(3):215-35.
14. Sano H, Takatsu T, Ciucchi B, Horner JA, Matthews WG, Pashley DH. Nanoleakage:
leakage within the hybrid layer. Oper Dent. 1995;20(1):18-25.
15. Sano H, Yoshiyama M, Ebisu S, Burrow MF, Takatsu T, Ciucchi B, et al. Comparative
SEM and TEM observations of nanoleakage within the hybrid layer. Oper Dent. 1995;20(4):160-
7.
16. Salz U, Mucke A, Zimmermann J, Tay FR, Pashley DH. pKa value and buffering
capacity of acidic monomers commonly used in self-etching primers. J Adhes Dent.
2006;8(3):143-50.
17. Van Meerbeek B, Yoshihara K, Yoshida Y , Mine A, De Munck J, Van Landuyt KL. State
of the art of self-etch adhesives. Dent Mater. 2011;27(1):17-28.
18. Van Meerbeek B, Yoshihara K. Clinical recipe for durable dental bonding: why and how?
J Adhes Dent. 2014;16(1):94.
19. Yoshida Y , Nagakane K, Fukuda R, Nakayama Y , Okazaki M, Shintani H, et al.
Comparative study on adhesive performance of functional monomers. J Dent Res.
2004;83(6):454-8.
20. Yoshihara K, Hayakawa S, Nagaoka N, Okihara T, Yoshida Y , Van Meerbeek B. Etching
Efficacy of Self-Etching Functional Monomers. J Dent Res. 2018;97(9):1010-6.

55
21. Tian F, Zhou L, Zhang Z, Niu L, Zhang L, Chen C, et al. Paucity of Nanolayering in
Resin-Dentin Interfaces of MDP-based Adhesives. J Dent Res. 2016;95(4):380-7.
22. Yaguchi T. Layering mechanism of MDP-Ca salt produced in demineralization of enamel
and dentin apatite. Dent Mater. 2017;33(1):23-32.
23. Sakano W, Nakajima M, Prasansuttiporn T, Foxton RM, Tagami J. Polymerization
behavior within adhesive layer of one- and two-step self-etch adhesives: a micro-Raman
spectroscopic study. Dent Mater J. 2013;32(6):992-8.
24. Walter R, Swift EJ, Jr., Nagaoka H, Chung Y , Bartholomew W, Braswell KM, et al. Two-
year bond strengths of "all-in-one" adhesives to dentine. J Dent. 2012;40(7):549-55.
25. Yoshida Y , Van Meerbeek B, Nakayama Y , Yoshioka M, Snauwaert J, Abe Y , et al.
Adhesion to and decalcification of hydroxyapatite by carboxylic acids. J Dent Res.
2001;80(6):1565-9.
26. Yoshioka M, Yoshida Y , Inoue S, Lambrechts P, Vanherle G, Nomura Y , et al.
Adhesion/decalcification mechanisms of acid interactions with human hard tissues. J Biomed
Mater Res. 2002;59(1):56-62.
27. Fujita Nakajima K, Nikaido T, Arita A, Hirayama S, Nishiyama N. Demineralization
capacity of commercial 10-methacryloyloxydecyl dihydrogen phosphate-based all-in-one
adhesive. Dent Mater. 2018;34(10):1555-65.
28. Van Landuyt KL, Snauwaert J, Peumans M, De Munck J, Lambrechts P, Van Meerbeek
B. The role of HEMA in one-step self-etch adhesives. Dent Mater. 2008;24(10):1412-9.
29. Yoshihara K, Yoshida Y , Nagaoka N, Fukegawa D, Hayakawa S, Mine A, et al. Nano-
controlled molecular interaction at adhesive interfaces for hard tissue reconstruction. Acta
Biomater. 2010;6(9):3573-82.

56
30. Zhang Z, Wang X, Zhang L, Liang B, Tang T, Fu B, et al. The contribution of chemical
bonding to the short- and long-term enamel bond strengths. Dent Mater. 2013;29(7):e103-12.
31. Yoshihara K, Yoshida Y , Hayakawa S, Nagaoka N, Irie M, Ogawa T, et al. Nanolayering
of phosphoric acid ester monomer on enamel and dentin. Acta Biomater. 2011;7(8):3187-95.
32. Yoshihara K, Yoshida Y , Nagaoka N, Hayakawa S, Okihara T, De Munck J, et al.
Adhesive interfacial interaction affected by different carbon-chain monomers. Dent Mater.
2013;29(8):888-97.
33. Linde A, Goldberg M. Dentinogenesis. Crit Rev Oral Biol Med. 1993;4(5):679-728.
34. Brannstrom M, Johnson G. Effects of various conditioners and cleaning agents on
prepared dentin surfaces: a scanning electron microscopic investigation. J Prosthet Dent.
1974;31(4):422-30.
35. Christensen GJ. Clinical factors affecting adhesion. Oper Dent. 1992;Suppl 5:24-31.
36. Hiraishi N, Kitasako Y , Nikaido T, Nomura S, Burrow MF, Tagami J. Effect of artificial
saliva contamination on pH value change and dentin bond strength. Dent Mater. 2003;19(5):429-
34.
37. Pashley DH, Tao L, Boyd L, King GE, Horner JA. Scanning electron microscopy of the
substructure of smear layers in human dentine. Arch Oral Biol. 1988;33(4):265-70.
38. Pashley DH, Tay FR, Breschi L, Tjaderhane L, Carvalho RM, Carrilho M, et al. State of
the art etch-and-rinse adhesives. Dent Mater. 2011;27(1):1-16.
39. Hashimoto M, Ito S, Tay FR, Svizero NR, Sano H, Kaga M, et al. Fluid movement across
the resin-dentin interface during and after bonding. J Dent Res. 2004;83(11):843-8.

57
40. Hosoya Y , Tay FR, Garcia-Godoy F, Pashley DH. Ultrastructural examination of one-step
self-etch adhesive bonded primary sound and caries-affected dentin. Am J Dent. 2008;21(6):368-
72.
41. Tay FR, Pashley DH. Aggressiveness of contemporary self-etching systems. I: Depth of
penetration beyond dentin smear layers. Dent Mater. 2001;17(4):296-308.
42. Koibuchi H, Yasuda N, Nakabayashi N. Bonding to dentin with a self-etching primer: the
effect of smear layers. Dent Mater. 2001;17(2):122-6.
43. Pashley DH, Ciucchi B, Sano H, Horner JA. Permeability of dentin to adhesive agents.
Quintessence Int. 1993;24(9):618-31.
44. Pashley DH, Nelson R, Kepler EE. The effects of plasma and salivary constituents on
dentin permeability. J Dent Res. 1982;61(8):978-81.
45. Yoo HM, Oh TS, Pereira PN. Effect of saliva contamination on the microshear bond
strength of one-step self-etching adhesive systems to dentin. Oper Dent. 2006;31(1):127-34.
46. Tenovuo J LfFSITA, Fejerskov OT (eds). . Textbook of clinical cariology. Copenhagen:
Munksgaard. 1994:17-43.
47. de Carvalho Mendonca EC, Vieira SN, Kawaguchi FA, Powers J, Matos AB. Influence of
blood contamination on bond strength of a self-etching system. Eur J Dent. 2010;4(3):280-6.
48. Koppolu M, Gogala D, Mathew VB, Thangala V , Deepthi M, Sasidhar N. Effect of saliva
and blood contamination on the bond strength of self-etching adhesive system- An in vitro study.
J Conserv Dent. 2012;15(3):270-3.
49. Xie J, Powers JM, McGuckin RS. In vitro bond strength of two adhesives to enamel and
dentin under normal and contaminated conditions. Dent Mater. 1993;9(5):295-9.

58
50. Duarte SJ, Lolato AL, de Freitas CR, Dinelli W. SEM analysis of internal adaptation of
adhesive restorations after contamination with saliva. J Adhes Dent. 2005;7(1):51-6.
51. Yoshida E, Uno S. V oids formation along the bonding interface between a smeared dentin
surface and all-in-one adhesives. Dent Mater J. 2004;23(4):643-9.
52. Navarra CO, Cadenaro M, Codan B, Mazzoni A, Sergo V , De Stefano Dorigo E, et al.
Degree of conversion and interfacial nanoleakage expression of three one-step self-etch
adhesives. Eur J Oral Sci. 2009;117(4):463-9.
53. Mahdan MH, Nakajima M, Foxton RM, Tagami J. Combined effect of smear layer
characteristics and hydrostatic pulpal pressure on dentine bond strength of HEMA-free and
HEMA-containing adhesives. J Dent. 2013;41(10):861-71.
54. Shinoda Y , Nakajima M, Hosaka K, Otsuki M, Foxton RM, Tagami J. Effect of smear
layer characteristics on dentin bonding durability of HEMA-free and HEMA-containing one-step
self-etch adhesives. Dent Mater J. 2011;30(4):501-10.
55. Kawaguchi-Uemura A, Mine A, Matsumoto M, Tajiri Y , Higashi M, Kabetani T, et al.
Adhesion procedure for CAD/CAM resin crown bonding: Reduction of bond strengths due to
artificial saliva contamination. J Prosthodont Res. 2018;62(2):177-83.
56. Duke ES, Phillips RW, Blumershine R. Effects of various agents in cleaning cut dentine. J
Oral Rehabil. 1985;12(4):295-302.
57. Sencer P, Wang Y , Walker MP, Swafford JR. Molecular structure of acid-etched dentin
smear layers--in situ study. J Dent Res. 2001;80(9):1802-7.
58. Brannstrom M, Glantz PO, Nordenvall KJ. The effect of some cleaning solutions on the
morphology of dentin prepared in different ways: an in-vivo study. ASDC J Dent Child.
1979;46(4):291-5.

59
59. Bridi EC, Leme-Kraus AA, Basting RT, Bedran-Russo AK. Long-term nanomechanical
properties and gelatinolytic activity of titanium tetrafluoride-treated adhesive dentin interface.
Dent Mater. 2019;35(10):1471-8.
60. Shortall AC. Cavity cleansers in restorative dentistry. Preliminary results from an in vitro
scanning electron microscope study. Br Dent J. 1981;150(9):243-7.
61. Kunawarote S, Nakajima M, Foxton RM, Tagami J. Effect of pretreatment with mildly
acidic hypochlorous acid on adhesion to caries-affected dentin using a self-etch adhesive. Eur J
Oral Sci. 2011;119(1):86-92.
62. Mountouris G, Silikas N, Eliades G. Effect of sodium hypochlorite treatment on the
molecular composition and morphology of human coronal dentin. J Adhes Dent. 2004;6(3):175-
82.
63. Haralur SB, Alharthi SM, Abohasel SA, Alqahtani KM. Effect of Decontamination
Treatments on Micro-Shear Bond Strength between Blood-Saliva-Contaminated Post-Etched
Dentin Substrate and Composite Resin. Healthcare (Basel). 2019;7(4).
64. Thanatvarakorn O, Nakajima M, Prasansuttiporn T, Ichinose S, Foxton RM, Tagami J.
Effect of smear layer deproteinizing on resin-dentine interface with self-etch adhesive. J Dent.
2014;42(3):298-304.
65. Thanatvarakorn O, Prasansuttiporn T, Thittaweerat S, Foxton RM, Ichinose S, Tagami J,
et al. Smear layer-deproteinizing improves bonding of one-step self-etch adhesives to dentin.
Dent Mater. 2018;34(3):434-41.
66. Montes MA, de Goes MF, Sinhoreti MA. The in vitro morphological effects of some
current pre-treatments on dentin surface: a SEM evaluation. Oper Dent. 2005;30(2):201-12.

60
67. Stona P, Borges GA, Montes MA, Junior LH, Weber JB, Spohr AM. Effect of polyacrylic
acid on the interface and bond strength of self-adhesive resin cements to dentin. J Adhes Dent.
2013;15(3):221-7.
68. Japan KNA. Kuraray Katana Clean Brochure. Manuracture material introduction. 2020.
69. Fukegawa D, Hayakawa S, Yoshida Y , Suzuki K, Osaka A, Van Meerbeek B. Chemical
interaction of phosphoric acid ester with hydroxyapatite. J Dent Res. 2006;85(10):941-4.
70. Hill JP, Shrestha LK, Ishihara S, Ji Q, Ariga K. Self-assembly: from amphiphiles to
chromophores and beyond. Molecules. 2014;19(6):8589-609.
71. Wang R, Shi Y , Li T, Pan Y , Cui Y , Xia W. Adhesive interfacial characteristics and the
related bonding performance of four self-etching adhesives with different functional monomers
applied to dentin. J Dent. 2017;62:72-80.
72. BISCO IS, IL., USA. Zirclean Instruction For Use. 2018.
73. Ivoclar Vivadent Inc. Amherst NU. Ivoclean Instruction For Use. 2011.
74. Chung CW, Yiu CK, King NM, Hiraishi N, Tay FR. Effect of saliva contamination on
bond strength of resin luting cements to dentin. J Dent. 2009;37(12):923-31.
75. Suryakumari NB, Reddy PS, Surender LR, Kiran R. In vitro evaluation of influence of
salivary contamination on the dentin bond strength of one-bottle adhesive systems. Contemp
Clin Dent. 2011;2(3):160-4.
76. Inoue S, Koshiro K, Yoshida Y , De Munck J, Nagakane K, Suzuki K, et al. Hydrolytic
stability of self-etch adhesives bonded to dentin. J Dent Res. 2005;84(12):1160-4.
77. Phark JH, Duarte S, Jr., Kahn H, Blatz MB, Sadan A. Influence of contamination and
cleaning on bond strength to modified zirconia. Dent Mater. 2009;25(12):1541-50.
78. Kuraray Noritake O, Japan. KATANA Cleaner Instruction For Use. 2020.

61
79. Helvatjoglu-Antoniades M, Koliniotou-Kubia E, Dionyssopoulos P. The effect of thermal
cycling on the bovine dentine shear bond strength of current adhesive systems. J Oral Rehabil.
2004;31(9):911-7.
80. 3M ESPE SPM, USA. Scotchbond Universal Adhesive Techanical Product Profile. 2016.
81. Ivoclar Vivadent Inc. Amherst NU. IPS Empress Direct Instructions For Use. 2018.
82. Duarte S, Jr., Phark JH, Varjao FM, Sadan A. Nanoleakage, ultramorphological
characteristics, and microtensile bond strengths of a new low-shrinkage composite to dentin after
artificial aging. Dent Mater. 2009;25(5):589-600.
83. Hass V , Abuna G, Pinheiro Feitosa V , Martini EC, Sinhoreti MA, Furtado Carvalho R, et
al. Self-Etching Enamel Bonding Using Acidic Functional Monomers with Different-length
Carbon Chains and Hydrophilicity. J Adhes Dent. 2017;19(6):497-505.
84. Moszner N, Salz U, Zimmermann J. Chemical aspects of self-etching enamel-dentin
adhesives: a systematic review. Dent Mater. 2005;21(10):895-910.
85. Reis A, Grandi V , Carlotto L, Bortoli G, Patzlaff R, Rodrigues Accorinte Mde L, et al.
Effect of smear layer thickness and acidity of self-etching solutions on early and long-term bond
strength to dentin. J Dent. 2005;33(7):549-59.
86. Wang Y , Spencer P. Continuing etching of an all-in-one adhesive in wet dentin tubules. J
Dent Res. 2005;84(4):350-4.
87. Fujita K, Ma S, Aida M, Maeda T, Ikemi T, Hirata M, et al. Effect of reacted acidic
monomer with calcium on bonding performance. J Dent Res. 2011;90(5):607-12.
88. Yoshihara K, Yoshida Y , Hayakawa S, Nagaoka N, Torii Y , Osaka A, et al. Self-etch
monomer-calcium salt deposition on dentin. J Dent Res. 2011;90(5):602-6.

62
89. Perdigao J. Dentin bonding-variables related to the clinical situation and the substrate
treatment. Dent Mater. 2010;26(2):e24-37.
90. Bowen RL, Eick JD, Henderson DA, Anderson DW. Smear layer: removal and bonding
considerations. Oper Dent Suppl. 1984;3:30-4.
91. Torney DL. The retentive ability of acid-etched dentin. J Prosthet Dent. 1978;39(2):169-
72.
92. Munoz MA, Luque-Martinez I, Malaquias P, Hass V , Reis A, Campanha NH, et al. In
vitro longevity of bonding properties of universal adhesives to dentin. Oper Dent.
2015;40(3):282-92.
93. Feitosa VP, Ogliari FA, Van Meerbeek B, Watson TF, Yoshihara K, Ogliari AO, et al. Can
the hydrophilicity of functional monomers affect chemical interaction? J Dent Res.
2014;93(2):201-6.
94. Van Landuyt KL, Yoshida Y , Hirata I, Snauwaert J, De Munck J, Okazaki M, et al.
Influence of the chemical structure of functional monomers on their adhesive performance. J
Dent Res. 2008;87(8):757-61.
95. Y . Yoshida SI. Chemical analyses in dental adhesive technology. J Dent Sci Rev.
2012;48:141–52.
96. Sai K, Shimamura Y , Takamizawa T, Tsujimoto A, Imai A, Endo H, et al. Influence of
degradation conditions on dentin bonding durability of three universal adhesives. J Dent.
2016;54:56-61.
97. Suliman AA, Schulein TM, Boyer DB, Kohout FJ. Effects of etching and rinsing times
and salivary contamination on etched glass-ionomer cement bonded to resin composites. Dent
Mater. 1989;5(3):171-5.

63
98. Silverstone LM, Hicks MJ, Featherstone MJ. Oral fluid contamination of etched enamel
surfaces: an SEM study. J Am Dent Assoc. 1985;110(3):329-32.
99. Amsler F, Peutzfeldt A, Lussi A, Flury S. Long-Term Bond Strength of Self-Etch
Adhesives to Normal and Artificially Eroded Dentin: Effect of Relative Humidity and Saliva
Contamination. J Adhes Dent. 2017;19(2):169-76.
100. Hitmi L, Attal JP, Degrange M. Influence of the time-point of salivary contamination on
dentin shear bond strength of 3 dentin adhesive systems. J Adhes Dent. 1999;1(3):219-32.
101. el-Kalla IH. Saliva contamination and resin micromorphological adaptation to cavity
walls using single-bottle adhesives. Am J Dent. 1999;12(4):172-6.
102. Yoshihara K, Nagaoka N, Okihara T, Kuroboshi M, Hayakawa S, Maruo Y , et al.
Functional monomer impurity affects adhesive performance. Dent Mater. 2015;31(12):1493-501.
103. Yoshida Y , Yoshihara K, Hayakawa S, Nagaoka N, Okihara T, Matsumoto T, et al. HEMA
inhibits interfacial nano-layering of the functional monomer MDP. J Dent Res.
2012;91(11):1060-5.
104. Cadenaro M, Breschi L, Rueggeberg FA, Suchko M, Grodin E, Agee K, et al. Effects of
residual ethanol on the rate and degree of conversion of five experimental resins. Dent Mater.
2009;25(5):621-8.
105. Pashley EL, Zhang Y , Lockwood PE, Rueggeberg FA, Pashley DH. Effects of HEMA on
water evaporation from water-HEMA mixtures. Dent Mater. 1998;14(1):6-10.
106. Tay FR, Pashley DH, Suh BI, Hiraishi N, Yiu CK. Water treeing in simplified dentin
adhesives--deja vu? Oper Dent. 2005;30(5):561-79.
107. Zhang ZY , Tian FC, Niu LN, Ochala K, Chen C, Fu BP, et al. Defying ageing: An
expectation for dentine bonding with universal adhesives? J Dent. 2016;45:43-52.

64
108. Camps J, Pashley DH. Buffering action of human dentin in vitro. J Adhes Dent.
2000;2(1):39-50.
109. Hicks J, Garcia-Godoy F, Flaitz C. Biological factors in dental caries: role of saliva and
dental plaque in the dynamic process of demineralization and remineralization (part 1). J Clin
Pediatr Dent. 2003;28(1):47-52.
110. Tani C, Finger WJ. Effect of smear layer thickness on bond strength mediated by three
all-in-one self-etching priming adhesives. J Adhes Dent. 2002;4(4):283-9.
111. Chan KM, Tay FR, King NM, Imazato S, Pashley DH. Bonding of mild self-etching
primers/adhesives to dentin with thick smear layers. Am J Dent. 2003;16(5):340-6.
112. Garcia MG, Poskus LT, Hass V , Amaral CM, Noronha-Filho JD, Silva EMD. Effect of
Calcium Hydroxide on Bonding Performance of an Experimental Self-etch Adhesive. J Adhes
Dent. 2018;20(1):57-64.
113. Tezvergil-Mutluay A, Mutluay M, Seseogullari-Dirihan R, Agee KA, Key WO, Scheffel
DL, et al. Effect of phosphoric acid on the degradation of human dentin matrix. J Dent Res.
2013;92(1):87-91.
114. Zhang Y , Wang Y . The effect of hydroxyapatite presence on the degree of conversion and
polymerization rate in a model self-etching adhesive. Dent Mater. 2012;28(3):237-44.
115. ISO/TS International Organization for Standardization G, Switzerland. 11405:2015
Dental materials - testing of adhesion to tooth structure. 08/04/2020.
116. Sartori N, Peruchi LD, Phark JH, Duarte S, Jr. The influence of intrinsic water
permeation on different dentin bonded interfaces formation. J Dent. 2016;48:46-54.

65
117. Cuevas-Suarez CE, da Rosa WLO, Lund RG, da Silva AF, Piva E. Bonding Performance
of Universal Adhesives: An Updated Systematic Review and Meta-Analysis. J Adhes Dent.
2019;21(1):7-26.
118. Li N, Nikaido T, Takagaki T, Sadr A, Makishi P, Chen J, et al. The role of functional
monomers in bonding to enamel: acid-base resistant zone and bonding performance. J Dent.
2010;38(9):722-30.
119. Wang H, Shimada Y , Tagami J. Effect of fluoride in phosphate buffer solution on bonding
to artificially carious enamel. Dent Mater J. 2007;26(5):722-7.
120. Pashley EL, Agee KA, Pashley DH, Tay FR. Effects of one versus two applications of an
unfilled, all-in-one adhesive on dentine bonding. J Dent. 2002;30(2-3):83-90.
121. Rueggeberg FA, Margeson DH. The effect of oxygen inhibition on an unfilled/filled
composite system. J Dent Res. 1990;69(10):1652-8.
122. Gale MS, Darvell BW. Thermal cycling procedures for laboratory testing of dental
restorations. J Dent. 1999;27(2):89-99.
123. Armstrong S, Breschi L, Ozcan M, Pfefferkorn F, Ferrari M, Van Meerbeek B. Academy
of Dental Materials guidance on in vitro testing of dental composite bonding effectiveness to
dentin/enamel using micro-tensile bond strength (muTBS) approach. Dent Mater.
2017;33(2):133-43.
124. Van Meerbeek B PM, Poitevin A, Mine A, Van Ende A, Neves A, et al. . Relationship
between bond-strength tests and clinical outcomes. Dent Mater. 2010;26(2):e100-21.
125. DeHoff PH, Anusavice KJ, Wang Z. Three-dimensional finite element analysis of the
shear bond test. Dent Mater. 1995;11(2):126-31.

66
126. Placido E, Meira JB, Lima RG, Muench A, de Souza RM, Ballester RY . Shear versus
micro-shear bond strength test: a finite element stress analysis. Dent Mater. 2007;23(9):1086-92.
127. Foong J, Lee K, Nguyen C, Tang G, Austin D, Ch'ng C, et al. Comparison of microshear
bond strengths of four self-etching bonding systems to enamel using two test methods. Aust Dent
J. 2006;51(3):252-7.
128. Tedesco TK, Garcia EJ, Soares FZ, Rocha Rde O, Grande RH. Effect of two microshear
test devices on bond strength and fracture pattern in primary teeth. Braz Dent J. 2013;24(6):605-
9.
129. Versluis A, Tantbirojn D, Douglas WH. Why do shear bond tests pull out dentin? J Dent
Res. 1997;76(6):1298-307.
130. Villela-Rosa AC, Goncalves M, Orsi IA, Miani PK. Shear bond strength of self-etch and
total-etch bonding systems at different dentin depths. Braz Oral Res. 2011;25(2):109-15.
131. Ikeda M, Tsubota K, Takamizawa T, Yoshida T, Miyazaki M, Platt JA. Bonding durability
of single-step adhesives to previously acid-etched dentin. Oper Dent. 2008;33(6):702-9.
132. Tjaderhane L, Nascimento FD, Breschi L, Mazzoni A, Tersariol IL, Geraldeli S, et al.
Strategies to prevent hydrolytic degradation of the hybrid layer-A review. Dent Mater.
2013;29(10):999-1011.
133. Ajami AA, Kahnamoii MA, Kimyai S, Oskoee SS, Pournaghi-Azar F, Bahari M, et al.
Effect of three different contamination removal methods on bond strength of a self-etching
adhesive to dentin contaminated with an aluminum chloride hemostatic agent. J Contemp Dent
Pract. 2013;14(1):26-33.

Abstract (if available)

Abstract Objectives: The aim of this study was to examine the effect of saliva contamination and a 10-MDP containing tooth cleaner on the notched shear bond strength (SBS) to human dentin using a universal adhesive system in self-etch mode. ❧ Materials and methods: One hundred and seven extracted intact human molars were sectioned to expose mid-coronal dentin. Selected specimens were embedded into acrylic resin and divided into 4 groups (n=40): Smear layer was created in all specimens. Group SU (control), bonding completed after smear layer creation

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Creator Hayashi-Wells, Rie (author)

Core Title Efficacy of a 10-MDP containing cleaner on the bond strength to contaminated dentin

School School of Dentistry

Degree Master of Science

Degree Program Biomaterials and Digital Dentistry

Publication Date 11/21/2020

Defense Date 08/13/2020

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag 10-MDP,cleaner,dentin,OAI-PMH Harvest,saliva,SBS,universal adhesives

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Phark, Jin-Ho (committee chair), Duarte, Sillas Jr. (committee member), Knezevic, Alena (committee member)

Creator Email riehayas@usc.edu,riehayashidds@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c89-396743

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Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

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