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Shear bond strength comparison of mesh, sandblasted and laser-etched orthodontic brackets

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Shear bond strength comparison of mesh, sandblasted and laser-etched orthodontic brackets

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Content 1

SHEAR BOND STRENGTH COMPARISON OF MESH, SANDBLASTED AND
LASER-ETCHED ORTHODONTIC BRACKETS

By

Peter Mark Vrontikis

A Thesis Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF SCIENCE
(CRANIOFACIAL BIOLOGY)

MAY 2015

PETER MARK VRONTIKIS

2

Table of Contents

ABSTRACT 3

List of Figures 4
List of Tables 5
List of Graphs 6

CHAPTER 1: BACKGROUND 7
Bonding 9
Acid Etching 8
Primer 8
Adhesive 10
Light Cure Devices 11
Bracket Design 12
Mesh 13
Sandblasted 15
Laser-etch 16
Sintered 17
Instron Testing Machine 18
Testing 19

CHAPTER 2: Research Objective 20

CHAPTER 3: Materials & Methods 21
Bracket Design 21
Composite Disk Preparation 22
Composite Disk Bonding 22
Shear Bond Testing 23

CHAPTER 4: Results 25
Statistical Analysis 25

CHAPTER 5: Discussion 29
Future Experimentation 33

CHAPTER 6: Conclusion 34

BIBLIOGRAPY 35

3

ABSTRACT

Objective
The purpose of this study is to compare the shear bond strengths of standard single mesh,
sandblasted and laser-etched orthodontic bracket bases. Our H
0
hypothesis is there is no
difference in shear bond strength of standard single mesh, sandblasted brackets and laser-etched
orthodontic bracket bases.
Methods
To compare bond strength of commercially available orthodontic brackets thirty-six brackets
were divided into three equal groups. Single mesh control (n=12), sandblasted bracket bases
(n=12), laser-etched bracket bases (n=12) were bonded to a composite disk and subjected to
shear bond strength tests using an Instron Universal Testing Machine.
Results

Shear bond strength (SBS) for all three groups ranged from 12.25 MPa to 34.99 MPa. Control
group (single-mesh) SBS ranged from 16.79 to 30.00 MPa (mean = 24.1072 MPa), sandblasted
group ranged from 21.05 to 34.99 MPa (mean =30.8143 MPa) and the laser-etched group ranged
from 12.25 to 29.43 MPa (mean =21.7709 MPa). A one-way ANOVA with post-hoc Tukey B
for group wise comparison was performed at α=0.05.
Conclusion

In this study, the surface treatment of orthodontic bracket bases using sandblasting resulted in
significantly higher shear bond strength compared to standard single mesh and laser-etched
bracket bases. When comparing the shear bond strength of laser-etched and control mesh bracket
bases, there was no significantly different from each other.

4

LIST OF FIGURES

FIGURE 1: MZ100 hybrid resin blocks 22
FIGURE 2: MZ100 disk with bonded bracket 23
FIGURE 3: Instron blade perpendicular to mounted disk with bonded bracket 24
FIGURE A: Sample mesh bracket at 25X magnification 27
FIGURE B: Sample mesh bracket at 50X magnification 27
FIGURE C: Sample mesh bracket at 100X magnification 27
FIGURE D: Sample mesh bracket at 200X magnification 27
FIGURE E: Tested mesh bracket at 25X magnification 27
FIGURE F: Tested mesh bracket at 50X magnification 27
FIGURE G: Tested mesh bracket at 100X magnification 27
FIGURE H: Tested mesh bracket at 200X magnification 27
FIGURE I: Sample sandblasted bracket at 25X magnification 27
FIGURE J: Sample sandblasted bracket at 50X magnification 27
FIGURE K: Sample sandblasted bracket at 100X magnification 27
FIGURE L: Sample sandblasted bracket at 200X magnification 27
FIGURE M: Tested sandblasted bracket at 25X magnification 27
FIGURE N: Tested sandblasted bracket at 50X magnification 27
FIGURE O: Tested sandblasted bracket at 100X magnification 27
FIGURE P: Tested sandblasted bracket at 200X magnification 27
FIGURE Q: Sample laser-etched bracket at 25X magnification 28
FIGURE R: Sample laser-etched bracket at 50X magnification 28
FIGURE S: Sample laser-etched bracket at 100X magnification 28
FIGURE T: Sample laser-etched bracket at 200X magnification 28
FIGURE U: Tested laser-etched bracket at 25X magnification 28
FIGURE V: Tested laser-etched bracket at 50X magnification 28
FIGURE W: Tested laser-etched bracket at 100X magnification 28
FIGURE X: Tested laser-etched bracket at 200X magnification 28

5

LIST OF TABLES

TABLE 1: Bond Strength (MPa) 25
TABLE 2: Bond Strength (MPa) ANOVA 25
TABLE 3: Bond Strength (MPa) Tukey B 26

6

LIST OF GRAPHS

GRAPH 1: Mean Bond Strengths 26

7

CHAPTER 1: BACKGROUND

Ever since Newman (1964) described the notion of eliminating the need to place orthodontic
bands on all teeth and replace them with bonded orthodontic brackets, people began to question
the loss of bond strength. Zachrisson et al. (1997) described some advantages of bonded brackets
including greater time efficiency with no need for separation, elimination of potential post
treatment band space, reduced contamination risks, efficiency of placement, greater patient
comfort, a more esthetic appearance, decreased risk of decalcification that may accompany loose
bands, and easier detection of caries resulting from greater visibility of the enamel. It is easy to
see all the benefits of a bonded appliance, but what about the negatives? Talpura et al. (2002)
described a bonded attachment must be able to withstand the shear, tensile, peel, and torsional
forces generated during treatment, as well as the dynamic forces transmitted to the teeth during
mastication and in occlusion (Maijer and Smith, 1981). If a patient’s bracket is unable to
successfully resist these forces the result with be a bond failure (Maijer and Smith, 1981). On the
contrary, a bracket with a very high bond strength is also counterproductive because this hinders
the removal of attachments at the completion of treatment, creating the potential for patient
discomfort and enamel damage (Retief, 1974). Zachrisson (1977) and Banks et al. (2007) both
reported high bond failure rates may result from orthodontic and masticatory forces, or from
moisture contamination during the bonding process due to isolation difficulties (Knoll et al.,
1986). Manufacturers have sought to address bond failure through improvements in adhesive
technology, attachment base design and increased base dimensions (Talpura et al., 2002).

8

Bonding

Conventional bonding of orthodontic brackets requires the use of 3 different agents to bond to
enamel; enamel conditioner (acid), primer, and adhesive resin.

Acid Etching

Buonocore’s (1955) contribution of acid etch technology has significantly changed clinical
practice in all fields of dentistry. Applying an acid to the enamel surface creates dissolution
which causes microporosities, these microporosities results in a micromechanical bond (Olsen et
al., 1997). Mardaga and Shannon (1982) determined the tensile bond strengths of an orthodontic
bonding system to enamel surfaces by using 37% phosphoric acid for 15, 20, 30, and 60 seconds.
Mardaga and Shannon (1982) reported a stepwise increase in bond strengths with an increase in
etching time (Legler et al., 1990). Results from Carstensen (1995) indicated with reduction of
phosphoric acid concentration from 37% to 2% showed a statistically significant decrease in
shear bond strength. When 37% phosphoric acid is used for bonding of metal brackets, the bond
strength between enamel and resin is often higher than that between resin and bracket
(Carstensen, 1995).

Primer
After enamel etching, a histological change in the enamel, beyond the complete dissolution of
the surface layer occurs (Bishara et al., 2000). The amount of acid etching can be estimated from
determining the lengths of resin tags (Bishara et al., 2000). After enamel etching, acrylic resin is
applied to the enamel surface, flowing into the histologic porosities, thereby forming a
mechanical bond (Bishara et al., 2000). The protocol for using a composite resin to attach
orthodontic brackets to the enamel comprises a series of technique-sensitive steps (Bishara et al.,
9

1998). Bond failure with composite resin has been attributed to moisture contamination by
gingival fluid, saliva, or water, therefore a dry field must be maintained (Zachrisson, 1977).
Introduced nearly 20 years ago, glass ionomers were used in various fields of dentistry due to its
positive characteristics including its successful use as cements in moist environments and its
cariostatic properties due to a low level fluoride release over an extended period (Christensen,
1991). The first glass ionomer cements consisted of two components: a calcium-aluminum
fluorosilicate glass powder and polyacrylic acid, which extended early setting stage, during
which the materials were highly soluble (Bishara et al., 2000). A second generation of glass
ionomer cements were created through the addition of both itaconic acid copolymers to increase
the reactivity of the polyacrylic acid and small quantities of tartaric acid to improve the rate of
hardening (Bishara et al., 2000, Kiockowski, 1989). The combination created a less viscous
cement with a shorter initial setting time (Kiockowski, 1989). Compton et al. (1992) reported
that light-cured glass ionomer cements exhibit greater shear bond strengths than the traditional
chemical cure glass ionomer cements (Bishara et al., 2000). Although glass ionomer cements
have high levels of fluoride release, they were found to have poor bond strength, in the range of
2.37 to 5.5 MPa (Wiltshire, 1994). Miguel et al. (1995) found glass ionomer cements to have a
greater bond failure rate than composite resins. In an attempt to provide greater fluoride release
and adequate bond strength, combinations of glass ionomer cements and composite resins have
been developed in resin modified glass ionomer cement (RMGIC) (Rix et al., 2001). One
disadvantage of direct bonding has been moisture control (Schaneveldt and Foley, 2002). In
response to the competitive advantages of RMGIC's abilities in moist environments,
manufacturers have developed moisture-insensitive primers (MIP, 3M Unitek, Monrovia, Calif)
and hydrophilic resin systems (Assure, Reliance Orthodontic Products, Itasca, Ill) (Schaneveldt
10

and Foley, 2002). According to the manufacturer, Assure Universal is a light-cured bis-GMA-
type resin bonding agent that bonds to normal, atypical, dry, or slightly contaminated enamel,
and it can be used with any light- or chemical-curing system (Öztopraka et al., 2007). Assure
primer is composed of a biphenyl-dimethacrylate, hydroxyethyl-methacrylate and acetone
mixure (Assure Bonding Resin MSDS, 2008). Öztopraka et al. (2007) found that both
conventional (Transbond XT) and hydrophilic (Assure) primers can produce the highest bond
strengths on uncontaminated enamel surfaces. Öztopraka et al. (2007) also showed that among
all blood-contaminated conditions, Assure had significantly higher shear bond strength values
than Transbond XT primer. Schaneveldt and Foley (2002) found that with saliva contamination
after application of primer, both MIP and Assure had significantly greater shear-peel bond
strengths than when contamination occurred before the application of each primer. Öztopraka et
al. (2007) showed that Transbond XT adhesive combined with Assure hydrophilic primer in a
dry environment had the greatest bond strength among several other primer/adhesive
combinations.

Adhesive
Tavas and Watts (1979) first described the use of visible light to cure composites used in
orthodontic bonding (Owens and Miller, 2000). Numerous advantages have been reported with
the use of visible light-cured resins, the main one being that rapid composite polymerization
occurs when the visible light spectrum (usually 450 to 470 nm wavelength)(Rod Greenlaw et al.,
1989). Visible light-cured composites provide ease of use, extended working time, improved
bracket placement, easier cleanup, and faster cure of the composite (Owens and Miller, 2000).
Generally, all mechanical properties of a composite resin improve with filler loading (Tecco et
11

al., 2005). Traditional dental composite resins are densely loaded with reinforcing filler particles
for strength and wear resistance (Tecco et al., 2005). Wear resistance increases with small,
highly packed filler particles (Tecco et al., 2005). Composites used for bonding of orthodontic
brackets range from traditional dense highly packed filler, to flow-able composites with reduced
filler, and hybrid with smaller filled particles (Tecco et al., 2005). The three types of filler
particles are: 1) traditional macro-fillers; 2) microfillers (pyrogenic silica), and 3) microfiller-
based complexes, with three subgroups, namely: a) splintered pre-polymerized microfilled
complexes; b) spherical polymer-based microfilled complexes and c) the agglomerated
microfiller complexes (Lang et at., 1992). Particles which are mechanically ground or crushed
from larger pieces of purely inorganic materials such as quartz, glass, borosilicate, or a ceramic
resulting in the particles taking on a splinter or irregular shape, producing sizes ranging from 0-1
to 1-100 μm (Lang et at., 1992). Transbond XT consisted of 99% silicon dioxide (SiO
2
), the
remaining includes small amounts of boron oxide (B
2
O
3
), aluminum oxide (Al
2
O
3
), strontium
oxide (SrO), fluoride (F), zinc oxide (ZnO), or phosphorus oxide (P
2
O
5
) (Iijimaa et al., 2010).
Transbond XT contains the largest irregular particles of its competitors, with sizes ranging from
approximately 0.5 to 10 μm (Iijimaa et al., 2010).

Light Cure Devices
The use of light-cured adhesives in dentistry began with pit-and-fissure sealants (Buonocore,
1970), then progressed to restorative materials (Buonocore and Davila, 1973) and eventually to
orthodontics for bonding (Sfondrini et al., 2001). The light source first used for curing composite
resins was an ultraviolet light (UV), which required 1 minute per millimeter of resin thickness
for curing (Sfondrini et al., 2001). Using light-curing adhesives in the orthodontic bonding
12

procedure reduced the risk of contamination and more accurate bracket placement; disadvantages
include the prolonged time required for bonding (1 minute per bracket) (Sfondrini et al., 2001).
Safety concerns with the long-term use of UV light caused visible light-curing to be developed
around 1980 (Tirtha et al., 1982). Compared with UV-cured resins, visible light-curing resins
were found to have a greater depth of curing (Sfondrini et al., 2001). The curing of visible light-
curing resins is based on the presence of camphorquinone, which is sensitive to light in the 470-
nm wavelength spectrum (Zachrisson, 1977). Several devices have been developed over the
years which produced greater power density in the curing region of the visible spectrum, 400–
500 nm wavelengths (Tsaia et al., 2004). Argon lasers, high-intensity halogen lights, and xenon
plasma arc lamps have all been shown to achieve rapid polymerization (Tsaia et al., 2004).
Currently light emitting diode (LED) curing lights are being used (Tsaia et al., 2004). LEDs are
known to use less power, have a longer life (Tsaia et al., 2004) and have a narrow spectral range
with a peak around 470 nm, which matches the optimum absorption wavelength for the
activation of the camphorquinone photoinitiator (Fujibayashi et al., 1998). According to
manufacturer's guidelines, light emitting diode curing lights can cure orthodontic composite
resins in 20 seconds (Transbond XT; 3M/Unitek, Monrovia, Calif) and resin-modified glass
ionomers in 40 seconds (Fuji Ortho LC; GC America Inc, Alsip, Ill) per bracket (Sfondrini et al.,
2001).

Bracket Design
Edward Angle is known for being the “Father of modern orthodontics not only for his
classification and diagnosis but his developing of orthodontic appliances (Proffit, 2007).
According to Proffit, Angle developed four major appliance systems: E-arch, Pin and Tube,
13

Ribbon arch and Edgewise. Contemporary edgewise appliance has evolved far beyond any of its
predecessors, which is the reason for it’s almost universal use today. The basic design of a
banded orthodontic bracket is a horizontal positioned 22 x 28 mils slot with twin wings, welded
to a band which is fitted and cemented around a tooth. Modern brackets have replaced the band
with a bracket pad which is bonded to the tooth surface. According to Proffit, the brackets and
tubes must be precisely manufactured within at least 1 mil. Until resent introduction of ceramic
and titanium brackets, most were fabricated entirely from stainless steel. Stainless steel brackets
are either stamped or cast. According to Proffit, cast brackets are both more accurate and more
durable. Original bracket base design with perforated bracket bases have been replaced by foil-
mesh bracket bases design (Maijer and Smith, 1981).

Mesh
Adhesion at the bracket cement interface is achieved most commonly by a mechanical undercut
into which the orthodontic adhesive extends before polymerization (Knox et al., 2000). While the
retention of most metal brackets is achieved with a fine brazed mesh, other bracket bases are
sandblasted, chemically etched, laser etched or sintered with porous metal powder (Wang et al.,
2004). To improve the esthetics of metal attachments, there has been a continuous trend to
reduce the size of the bracket and the bracket base (Maijer and Smith, 1981). With the evolution
of adhesive systems, the bracket bases have become smaller (Maijer and Smith, 1981). MacColl
et al. (1998) found there to be no statistically significant difference in shear bond strength
between bracket pads 6.82 and 12.35 mm
2
. A reduction in bond strength was associated with the
reduction of base surface area from 6.82 to 2.38 mm
2
, indicating no need to increase base surface
area beyond 6.82 mm
2
(MacColl et al., 1998). Mechanical retention of orthodontic brackets was
14

enhanced by placing undercuts in the cast bracket bases or by welding different diameter (single
mesh) or multiple layers (double mesh) of foil mesh to the bracket base (Bishara et al., 2004).
Deleterious effects of welding include weld spots that reduce the base retentive area and weld
spurs that prevent complete seating of the base against tooth structure (MacColl et al., 1998).
Brazing is process where two metal pieces are joined by a filler metal which is melted and forced
to flow into the entire joint of the metals. Welding also fuses metals together, however welding
utilizes contact points when joining metals together rather than the entire joint of the metals.
Brazing bracket bases produces superior bond strength over a welded bracket (MacColl et al.,
1998). Bracket base morphology can influence the strength of the bracket cement interface by
the geometry (depth, size, and distribution) of the cement tags and stress distribution within the
adhesive-bracket interface (Knox et al., 2000). The bond strength at each bracket base appears to
be strongly influenced by the type of adhesive used, although any particular type of adhesive
would appear to perform differently with the various bracket bases (Knox et al., 2000). Knox et
al. (2000) showed that 60-, 80-, and 100- gauge foil mesh bases all have significantly different
mesh spacing, with the 60- gauge having the most amount of space. 60- and 80- gauge bases
showed no significant difference in bond strength while 60- gauge mesh base provided a
significantly higher bond strength than the 100- gauge mesh base (Knox et al., 2000). The
performance of the 60- gauge mesh base with the light-cured adhesives could reflect the
improved penetration of the curing light within the larger mesh spaces (Knox et al., 2000).
However, the 60-gauge mesh base may provide a size and distribution of resin tags, which
promotes improved stress distribution and favorable penetration of these adhesives (Knox et al.,
2000). Sorel et al. (2002) found that bond failures of brackets with mesh bases are located at the
bracket-adhesive interface.
15

Sandblasted
Sandblasting is a procedure that uses a high-speed stream of typically 50 μm or 90 μm aluminum
oxide particles propelled by compressed air (Sharma-Sayal et al., 2003). The procedure is also
referred to as micro-etching and micro-abrasion used interchangeably in research articles.
Although initially introduced as a method to roughen the surface of many dental materials before
cementation to enhance bond strength, later its application has been extended to orthodontics to
roughen the internal surfaces of bands and bracket bases (Sonis, 1996). The technique of
sandblasting a bracket is least likely to damage the bracket base (Sharma-Sayal et al., 2003). This
process increases the surface area of composite bonding causing mechanical retention due to the
micro-asperity of the bracket mesh (Tavares et al., 2006). Tavares et al. (2006) described that in
spite of its increasingly widespread use for recycling purposes, aluminum-oxide blasting
technique was originally intended to enhance the mechanical retention of new brackets and
improve bracket bonding to restored teeth as well as to prepare the enamel surface (Canay et al.,
2000, Mccabe et al., 1993).
Many researchers have been interested in the effects of sandblasting. Some investigators have
reported that rebond shear bond strength (SBS) values were higher after sandblasting, but others
reported no significant differences (Sharma-Sayal et al., 2003). Zachrisson and Büyüky¦lmaz
(1993) found that sandblasting improves the retention and increases the bond strength when
bonding to gold, porcelain, and amalgam. Several authors (Zachrisson, 1994), (Zachrisson and
Büyüky¦lmaz, 1993), (Millettet al., 1993), (Wiltshire, 1994) and (MacColl et al. 1998) have
independently found that sandblasting bracket bases greatly increases their retentive surface
(Canay et al., 2000). MacColl et al. (1998) used a Danville portable sandblasting unit (Danville
Engineering Inc.) with 50 μm aluminum oxide positioned 10 mm from the bracket base to
16

roughen the bracket surface. The conclusion of that study was that the retention of foil-meshed
brackets is significantly enhanced when utilizing sandblasting before bonding to the teeth
(MacColl et al., 1998). Canay et al. (2000), sandblasted enamel using 50 μm aluminum oxide
and found that the highest mean bond strength was obtained with sandblasting followed by acid
etching. Tavares et al., (2006) found that when sandblasting a bracket, the distance of 10 mm
from the device tip to the bracket base caused no damage to the brackets. Montero et al. (2014)
stated there is a lack of studies that compare the effects of particle size for sandblasting brackets.
Sunna and Rock (2014) found that sandblasting enhances the retentive nature of metals by
increasing the surface area and thinning the oxide layer of stainless steel and it has been
suggested as a way of improving the bond at the bracket base. Sandblasting with 60 μm alumina
for 3 seconds at a distance of 10 mm has been shown by scanning electron microscope (SEM)
examination to produce the best micro-roughened surface to allow effective mechanical bonding
(Sunna and Rock, 2014). Sandblasting has been shown to increase bond strengths by 22% and
mean survival time was significantly longer for brackets bonded to premolars after sandblasting
than for untreated brackets (Millett et al., 1993). Similarly MacColl et al. (1998) found the use of
a portable sandblasting unit for 5 seconds increased bond strength by between 18 and 24%.

Laser-etched
In orthodontics, lasers are used for different purposes such as etching enamel, accelerating tooth
movement, decreasing pain and the removal of adhesive residues on the surface of enamel after
debonding (Ishida et al., 2011). The different types of lasers used in dentistry include; Erbium,
chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG), erbium-doped yttrium aluminium
garnet (Er:YAG), carbon dioxide (CO2), and diodes-laser silver arsenide-aluminum (Ga/Al/As
diode) (Ishida et al., 2011). The smooth surface of an orthodontic bracket base can be treated by
17

a Nd:YAG laser to create retention groves for the adhesive. The laser beam is scanned over the
base surface, melting and evaporating the metal and burning hole-shaped retention groves in the
base (Sorel et al., 2002). Er,Cr:YSGG laser has also been used successfully for surface treatment
of dental composites, with similar effects to that of sandblasting technique (Ahrari et al., 2012).
Ishida et al (2011) found that Er,Cr:YSGG laser with a power output of 3.75 W, a wave length of
2.78 lm, a pulse duration of 140 ls, a frequency of 20 Hz can promote the use of recycled
brackets by providing SBS values comparable to sandblasted attachments (Ahrari et al., 2012).
Ahrari et al. (2012) also found that bond strengths of brackets recycled with aluminum oxide
blasting or Er,Cr:YSGG laser were significantly higher than those for the new brackets as a
result of possible increase in micromechanical retention of the mesh. Sorel et al. (2002) found
that Nd:YAG laser-etched bracket bases had a bond strength twice that of the foil mesh brackets,
with a bond failure located at the enamel-adhesive interface. Similarly, Lee et al. (2003)
determined the bond failure of laser-etching at the enamel-resin interface.

Sintered
Hanson et al. (1983) believed an improved overall bond strength may be attainable through the
use of a coating on the bracket surface by a microscopic porous metal powder. They showed that
the large surface area and intricate microscopic void network of the powder coating provided
better mechanical interlocking with orthodontic cement and significant increase in bond strength
compared to mesh bases. The procedure consisted of a special sintering process to fuse stainless
steel powder particles smaller than 44 μm to an orthodontic attachment to create strongly
cohesive coatings roughly 0.005 inch thick. However, the adhesive bond strengths recorded were
lower (2.14-9.28 MPa) than those previously reported by Maijer and Smith (1981). This was
18

later attributed to differences in experimental design, bracket base design and improper adhesive
mixture (Ferguson et al., 1984).

Instron Testing Machine
The most common uses of the universal testing instruments are for tensile, compression, bend,
peel, shear, tear and cyclic tests (Pickett et al., 2001). Dual column systems are multi-purpose
instruments that are commonly used for plastics, metals, rubber materials, automotive
components, composites, and non-ambient temperature applications (Instron Corp, 2013).
Considerable research has been conducted in evaluating the bond strength of various orthodontic
bracket-bonding systems (Pickett et al., 2001). Traditionally, orthodontic bonding systems have
been evaluated by means of in vitro shear bond strength tests using a universal testing machine
such as the Instron universal testing machine (Instron Corp, Canton, Mass) (Pickett et al., 2001).
A universal testing machine is considered the standard when assessing bond strength values in
vitro based (Pickett et al., 2001). To date, there are no validated devices designed to measure and
record actual debonding forces in vivo (Pickett et al., 2001). Shear bond testing on an Instron
universal testing machine (Instron Corp, Canton, Mass) requires the following steps: a blade is
placed at the bracket base-enamel interface at the occlusal side of the bracket using a crosshead
speed of .5 mm/min; brackets were shear tested to failure (Cozza et al., 2006). The force
producing failure is recorded in Newtons and converted into megapascals by dividing the
measured force values by the mean surface area of the brackets (Cozza et al., 2006).

19

Testing
Shear bond tests typically involve a combination of shear and peel forces because force is
applied at a distance from the bonding interface (Klocke and Kahl-Nieke, 2005). Three main
areas for the location of the debonding force can be identified: bracket base (close to the enamel–
bracket interface), area of the ligature groove of the bracket, and bracket wings (Klocke and
Kahl-Nieke, 2005). Klocke and Kahl-Nieke (2005) found that there was a decrease in bond
strength when forces were applied to the bracket wings. They also described that typically the
literature does not report at what point on the bracket that the force was applied. Presently there
is no standard protocol for SBS testing and shear testing force point locations are not typically
published. Methods of bond strength evaluation test the cohesive strength of the cement and the
strength of bracket-cement and cement–enamel interfaces, recording only the weakest element of
this system (Knox et al., 2000). One of the most often cited values for clinically acceptable bond
strength of approximately 6–8 MPa was given by Reynolds (1975) (Klocke and Kahl-Nieke,
2005). Adhesion at the bracket cement interface is achieved, most commonly by the provision of
a mechanical undercut into which the orthodontic adhesive extends before polymerization (Knox
et al., 2000). Most in vitro investigations of bond failure have shown that the most common
failure site is the bracket-adhesive interface for both metal and ceramic brackets (Jan Ødegaard
and Dietmar Segner, 1988). Most failure sites are between enamel-adhesive and adhesive-
bracket interfaces (Wang et al., 2004). Miller (1981) showed that as the number of bond failures
at the adhesive-bracket interface increase, the number of failures due to bracket or enamel
fracture decrease (Bordeaux et al., 1994). In order to determine the true strength of bracket
interface, a study must isolate the bracket-adhesive layer (Knox et al., 2000).

20

CHAPTER 2: RESEARCH OBJECTIVE

The purpose of this study is to compare the shear bond strengths of standard single mesh,
sandblasted and laser-etched orthodontic bracket bases. Our H
0
hypothesis is there is no
difference in shear bond strength of standard single mesh, sandblasted brackets and laser-etched
bases orthodontic brackets.

21

CHAPTER 3: MATERIALS & METHODS

Bracket Design
To compare bond strength of commercially available single mesh orthodontic brackets (control
n=12), with same design cast brackets with either sandblasted bases (n=12) or laser-etched
(n=12) bases bonded to a composite disk. A commercially available American Orthodontic
(A.O) Mini Master Series maxillary right central incisor bracket was selected as the control for
our study. A.O’s Mini Master bracket base contains an 80 gauge brazed mesh base, which is
considered the industry standard retention system. A Stereolithography (STL) file of the
maxillary right central incisor was provided by A.O. A replica bracket, minus the control bracket
mesh system, was fabricated from the STL file: 3D printed in wax pattern (Jewelry Art, LA) and
then casted using lost wax technique (Burbank Laboratory, Burbank, CA). Twenty-four
replicated brackets were evenly divided into two equal groups. One group was treated by
sandblasting bracket pads using MacroCab sandblasting unit (Danville Engineering, San Ramon,
CA) with 50 μm aluminum oxide at 90 psi for 9 seconds, with the tip held approximately 10 mm
from the bracket (MacColl et al., 1998, Olsen et al., 2007, Wanderley et al. 2005, Canay et al.,
2000). The other group of twelve brackets was laser etched by melting and evaporating the metal
and burning hole-shapes providing retention groves in the pad of the bracket (Figure S), (Caliber
engraving, Brea) (Sorel et al,. 2002). A Nd:YAG laser was used with a power output of 100 W at
24 amps at a frequency of 18 Hz with the lens size at 163mm. The surface area of the bracket
pad for all brackets was measured to be 10.87 mm
2
. Brackets were cleaned by rubbing with 91%
isopropyl alcohol for 2 minutes and air-dried for 1 min (MacColl et al., 1998).

22

Composite Disk Preparation
Thirty-six MZ100 (3M Unitek, Monrovia, CA) hybrid resin composite disks were cut 2mm thick
from blocks (Figure 1) using a water-cooled diamond band saw. Composite disks were cleaned
with distilled water for five seconds and allowed air dry. One side of the composite disk was
marked with an ‘X’ and would not be used. The other side was completely painted using a black
permanent marker. Each disk was sandblasted using 50 μm aluminum oxide sand for 10 seconds
removing all markings to insure the complete surface was cleaned (MacColl et al., 1998, Olsen et
al., 2007, Wanderley et al. 2005, Canay et al., 2000). Composite disks were then rinsed with
distilled water for 10 seconds and blown dry for 5 seconds to remove any remaining aluminum
oxide sand.

(Figure 1), MZ100 hybrid resin blocks
Composite Disk Bonding
Thirty-six composite disks were etched for 20 seconds using 37% phosphoric acid and rinsed
with distilled water for 10 seconds and blown dry for 10 seconds (MacColl et al., 1998, Sorel et
al., 2002, Olsen et al., 2007, Canay et al., 2000, Carstensen, 1995, Schaneveldt and Foley, 2002,
Bishara et al., 1998, Zeppieri et al., 2003). Assure composite resin (Reliance Orthodontics,
Itasca, IL) was applied with using a micro brush and dabbed in for 5 seconds (Webster et al.,
23

2001, Schaneveldt and Foley, 2002, Rix et al., 2001). A 1 second blast of canned air was used to
displace any excess primer (Schaneveldt and Foley, 2002, Zeppieri et al., 2003). Transbond XT
(3M Unitek, Monrovia, CA) was applied to the bracket pad and placed under a 1kg weight and
excess Transbond XT was removed (Sharma-Sayal et al., 2003, Sorel et al., 2002, Olsen et al.,
2007, Bishara et al., 2004, Knox et al., 2000, Schaneveldt and Foley, 2002, Rix et al., 2001,
Bishara et al., 1998, Bishara et al., 2001, Zeppieri et al., 2003, Webster et al., 2001, Schaneveldt
and Foley, 2002, Rix et al., 2001, Bishara et al., 1998, Zeppieri et al., 2003). Each side of the
bracket was light-cured using the Ortholux™ Luminous Curing Light 1600 mW/cm
2
(3M
Unitek, Monrovia, CA), for 12 seconds a side totaling 48 seconds (Figure 2) (Schaneveldt and
Foley, 2002, Rix et al., 2001, Bishara et al., 1998, Zeppieri et al., 2003). Bonding steps were
repeated for all thirty-six brackets. Samples were stored in distilled water at room temperature
for 48 hours (Wanderley et al. 2005, Canay et al., 2000).

(Figure 2) Brackets bonded to cut MZ100 disks
Shear Bond Testing
Bonded bracket disks were placed in an Instron 5960 Dual Column Tabletop Universal Testing
Systems (Instron Corp., Grove City, PA) connected to a computer (MacColl et al., 1998, Sorel et
al., 2002, Wanderley et al. 2005, Webster et al., 2001, Knox et al., 2000, Schaneveldt and Foley,
2002, Lee et al., 2003, Zeppieri et al., 2003). Each sample secured by a “C” clamp, locking the
sample into a vertical position, allowing the blade of the Instron machine to apply pressure 90
24

degrees to the occlusal portion of the bracket at the junction of the adhesive-bracket interface
parallel to the composite disk (Figure 3) (MacColl et al., 1998, Sorel et al., 2002, Wanderley et
al. 2005, Webster et al., 2001, Knox et al., 2000, Schaneveldt and Foley, 2002, Bishara et al.,
1998, Bishara et al., 2001). Shear bond testing was performed on each sample with a crosshead
speed of 0.5 mm/min until bond failure was achieved (MacColl et al., 1998, Sorel et al., 2002,
Wanderley et al. 2005, Webster et al., 2001, Knox et al., 2000). The shear bond strength was
calculated for all thirty-six samples and converted to megapascal (MPa) (MacColl et al., 1998,
Sorel et al., 2002, Wanderley et al. 2005, Webster et al., 2001, Knox et al., 2000, Schaneveldt
and Foley, 2002, Bishara et al., 1998, Zeppieri et al., 2003). A one-way ANOVA with post-hoc
Tukey B for group wise comparison was performed at α=0.05.

(Figure 3) Instron blade approaching a bonded bracket

25

CHAPTER 4: RESULTS

Four outliers in our study were removed to normalize the data, two from the control group and
one each from the sandblasted and laser-etched groups. Shear bond strength (SBS) ranged from
12.25 MPa to 34.99 MPa for all samples. Control group (single-mesh) SBS ranged from 16.79 to
30.00 MPa (mean = 24.1072 MPa), sandblasted group ranged from 21.05 to 34.99 MPa (mean
=30.8143 MPa) and the laser-etched group ranged from 12.25 to 29.43 MPa (mean =21.7709
MPa) (Table 1).
Statistical Analysis
A one-way ANOVA with post-hoc Tukey B for group wise comparison was performed at
α=0.05. Surface treatment using sandblasting resulted in significantly higher SBS compared to
control and laser-etched groups, which were not significantly different from each other (Table
3).
Table 1:
Bond Strength (MPa)

N Mean Std. Deviation Minimum Maximum
Control *10 24.1072 4.01940 16.79 30.00
Sandblasted *11 30.8143 4.47427 21.05 34.99
Laser Etched *11 21.7709 5.39042 12.25 29.43
*Four outliers were removed to normalize the date. 2 from the control group and 1 from
sandblasted and laser etched groups
Table 2:
ANOVA
Bond Strength (MPa)

Sum of
Squares Df Mean Square F Sig.
Between Groups 482.640 2 241.320 11.001 .000
Within Groups 636.157 29 21.936

Total 1118.798 31

26

Table 3:
Bond Strength (MPa)
Tukey B
a,b

Group N
Subset for alpha = 0.05
1 2
Laser Etched 11 21.7709

Control 10 24.1072

Sandblasted 11

30.8143
Means for groups in homogeneous subsets are
displayed.
a. Uses Harmonic Mean Sample Size = 10.645.
b. The group sizes are unequal. The harmonic mean of
the group sizes is used. Type I error levels are not
guaranteed.

Graph 1:

(Graph 1) Mean Bond Strengths

0
5
10
15
20
25
30
35
1
Control Sandblasted Laser Etched
Mean Bond Strength (MPa)
27

FIGURES A B C D

E F G H

Figures A-D, Sample mesh brackets with SEM magnification of: A)25X B) 50X C)100X
D)200X
Figures E-H, Tested mesh brackets with SEM magnification of: A)25X B) 50X C)100X
D)200X

FIGURES I J K L

M N O P

I-L, Sample sandblasted brackets with magnification of: A)25X B) 50X C)100X D)200X
M-P, Tested sandblasted brackets with magnification of: A)25X B) 50X C)100X D)200X

28

FIGURES Q R S T

U V W X

Q-T, Sample laser-etched brackets with magnification of: A)25X B) 50X C)100X
D)200X
U-X, Tested laser-etched brackets with magnification of: A)25X B) 50X C)100X
D)200X

29

CHAPTER 5: DISCUSSION

The study of bonding an orthodontic bracket to a tooth involves the sandwiching of the bracket-
adhesive and adhesive-enamel complexes (MacColl et al., 1998, Sorel et al., 2002, Wanderley et
al. 2005, Canay et al., 2000, Webster et al., 2001, Knox et al., 2000, Schaneveldt and Foley,
2002, Rix et al., 2001, Lee et al., 2003, Zeppieri et al., 2003). Several shear bond studies have
used teeth in their experiment (MacColl et al., 1998, Sorel et al., 2002, Wanderley et al. 2005,
Canay et al., 2000, Webster et al., 2001, Knox et al., 2000, Schaneveldt and Foley, 2002, Rix et
al., 2001, Lee et al., 2003, Zeppieri et al., 2003). Several factors contribute to variations in bond
failure to natural teeth during shear bond testing: decalcification, enamel contour, enamel
cracking, bracket contour and uneven force distribution (Sorel et al., 2002, Bishara et al., 2004,
Schaneveldt and Foley, 2002, Rix et al., 2001, Lee et al., 2003). Typically these factors cause
failure within the enamel-adhesive layer (Sorel et al., 2002, Bishara et al., 2004, Schaneveldt and
Foley, 2002, Rix et al., 2001, Lee et al., 2003). In using a composite disk we were able to create
a consistent reproducible bond surface, eliminating bond failures associated with decalcification,
enamel contour and enamel cracking. At the time of our study, no literature could be found using
orthodontic brackets bonded to a composite disk for SBS testing. As a substitute for enamel,
MZ100 composite disks were selected to provide reproducible flat bonding surface. By using a
maxillary central incisor, we chose a bracket pad with a relatively flat surface, which when
combined with a composite disk eliminates bond failure due to improper enamel and bracket
contour (Sorel et al., 2002, Rix et al., 2001). In order to have a successful shear bond test, a force
(Instron blade) must be applied parallel to the bracket bases (Wanderley et al. 2005, Schaneveldt
and Foley, 2002, Rix et al., 2001). The composite disk with the bonded bracket was clamped
vertically in the Instron machine, allowing the machine blade to apply a force in the inciso-
30

gingival direction at the bracket-adhesive interface and parallel to the composite disk (Figure 3)
(MacColl et al., 1998, Wanderley et al. 2005, Schaneveldt and Foley, 2002, Rix et al., 2001).
This eliminates bond failures associated with uneven force distribution (Rix et al., 2001). Bond
failures in all three groups of our study occurred in bracket-adhesive layer, indicating bonding
strength at the enamel-adhesive interface is superior to the bonding strength at the bracket-
adhesive interface in our study (Sorel et al., 2002). Previous studies have reported that laser-
etched bracket failures are typically located within the enamel-adhesive layer (Sorel et al., 2002,
Lee et al., 2003). We believe by substituting enamel for a composite disk, we removed factors
such as decalcification, enamel contour, enamel cracking, bracket contour and uneven force
distribution, and therefore eliminated or reduced bond failures within the ‘enamel’-adhesive
layer (Schaneveldt and Foley, 2002). This allowed us to focus of our study to the bracket-
adhesive interface, which is directly affected by the retentive bracket design (Sorel et al., 2002).
One of the most often cited values for clinically acceptable bond strength of approximately 6–8
MPa was given by Reynolds (1975). Klocke and Kahl-Nieke, (2005) identified three main areas
for the location of the debonding force in shear bond testing: bracket base, area of the ligature
groove of the bracket, and bracket wings. They found that there was a decrease in bond strength
when forces were applied to the bracket wings, in which case the peeling effect is maximized.
They also described that many papers do not report the force point location of SBS testing on the
bracket. Presently there is no standard protocol for shear testing force points and these locations
are not typically published. Therefore Katona (1997) suggested the use of a standardized testing
method for bracket testing, where force point locations on the bracket will be consistent. With
that in mind we positioned the Instron blade evenly at the junction of the bracket and adhesive
interface, parallel to the surface of the composite disk. Methods of bond strength evaluation test
31

the cohesive strength of the cement, the strength of bracket-adhesive and adhesive-enamel
interfaces, recording only the weakest element within this system (Knox et al., 2000). All three
of our test groups produced shear bond strength values of ranging from 12.25 MPa to 34.99
MPa. When comparing the SBS values of Reynolds (1975), we contribute our elevated shear
bond values to eliminating enamel as our bonding substrate, removing common problems
associated with bond failure.
Scanning electron microscope (SEM) examinations have revealed different surface
characteristics of the three groups (Figures A-X). The control mesh group (Figure A-D) showed
large spaces where adhesive can form mechanical retention (Webster et al., 2001). SEM
magnification of 50X, 100X and 200X shows that virtually all of the adhesive remains in
between the mesh and not on the actual mesh itself (Figures F-H). Similarly, the laser-etch test
group (Figure U-F) showed a large collection of adhesive remaining in the deepest spaces of the
bracket (Webster et al., 2001). For the sandblasted test samples, we did not see large spaces or
areas of adhesive (Figures M-P). Instead we see a much more evenly distributed flat surface
(Figures M-P). When comparing an untested sandblasted bracket under 200X magnification
(Figure L), with a tested bracket of the same magnification (Figure P) we can see the
appearance of a much smoother surface. We agree with Sunna and Rock (2014), Schaneveldt and
Foley, (2002), and Rix et al., (2001) and hypothesize that shallow roughness of the sandblasted
bracket (Figure N) allowed for an increase in bondable surface area and caused a thinning of the
oxide layer, both resulting in an increase in SBS. In addition we believe using a highly flow-able
primer like Assure might have also allowed the material to have an increased flow into these
shallow roughened areas of the bracket bases, therefore utilizing a larger surface area increasing
the SBS (MacColl et al., 1998, Sharma-Sayal et al., 2003, Olsen et al., 2007, Wanderley et al.
32

2005, Canay et al., 2000, Webster et al., 2001). As a result, our H
0
hypothesis that there is no
difference in bonding strength among the three groups of brackets with different bases was
rejected. Caution may be taken when interpreting the outcome of our study. The types of
material we used in the samples were different. The control brackets were made of chromium-
nickel stainless steel, which is much softer than the cobalt-chromium brackets of the sandblasted
and laser-etched groups. However, for the chromium-nickel brackets with mesh, the failure is
mostly at the mesh-adhesive interface. The bonding strength at the chromium-nickel-adhesive
interface is likely to be very weak and should unlikely affect the strength at the mesh-adhesive
interface. We have speculated that using laser-etching would allow for an increased mechanical
retention (Sorel et al., 2002, Lee et al., 2003). However, the outcome of our study seems to
suggest that sandblasted orthodontic brackets may have significantly higher bond strength when
compared to our control and laser-etched brackets. We credited the higher bond strength of the
sandblasted brackets to a higher bondable surface area of bracket-adhesive interface (MacColl et
al., 1998, Sharma-Sayal et al., 2003, Olsen et al., 2007, Wanderley et al. 2005, Canay et al.,
2000, Webster et al., 2001). Sandblasting causes shallow irregularities in the bracket (Figure L),
allowing more of the bonding agent to flow into these irregularities (Figure P) (MacColl et al.,
1998, Sharma-Sayal et al., 2003, Olsen et al., 2007, Wanderley et al. 2005, Canay et al., 2000,
Webster et al., 2001). SEM examination of the control and laser-etched bracket reveal deeper
valleys which we believe does not allow the primer and adhesive to fully flow into these areas,
thus not completely utilizing the bondable surface area (Figures C,S) (Olsen et al., 2007,
Wanderley et al. 2005, Canay et al., 2000, Webster et al., 2001). However atomic force
microscopy would need to be performed to support our findings. Atomic force microscopy is an
33

extremely powerful and expensive test to run and we did not have access to this type of
instrumentation.

Future Experimentation
In this experiment 50 μm aluminum oxide was used. We speculated using 50 μm sand particles
along with the highly flow-able Assure (reliance) might have, created a greater bondable surface
area than using the larger 90 μm aluminum oxide (Sharma-Sayal et al., 2003, Olsen et al., 2007,
Wanderley et al. 2005, Canay et al., 2000). Thus the experiment of comparing sandblasted
brackets using 50 μm aluminum oxide sand and 90 μm aluminum would be necessary to support
our findings. Utilizing different primers in future studies, with SEM examination of infiltration
of the primers into the spaces created with different base treatment would also be an area of
future exploration.

34

CHAPTER 6: CONCLUSIONS

In this study, the surface treatment of orthodontic bracket bases using sandblasting resulted in
significantly higher shear bond strength compared to standard single mesh and laser-etched
bracket bases. When comparing the shear bond strength of laser-etched and control mesh bracket
bases, there was no significantly different from each other.

35

REFERENCES

1. G.A. MacColl, P.E. Rossouw, K.C. Titley, Dip Paedo. (1998) The relationship
between bond strength and orthodontic bracket base surface area with conventional
and microetched foil-mesh bases. Am J Orthod Dentofacial Orthop 113(3): 276–281

2. Seema K Sharma-Sayal, P.Emile Rossouw, Gajanan V Kulkarni, Keith C Titley.
(2003) The influence of orthodontic bracket base design on shear bond strength.
Am J Orthod Dentofacial Orthop 124(1): 74–82

3. Olivier Sorel, Rafeh El Alam, Francis Chagneau, Guy Cathelineau (2002).
Comparison of bond strength between simple foil mesh and laser-structured base
retention brackets. Am J Orthod Dentofacial Orthop. 122(3): 260–26

4. Marc E. Olsen, Samir E. Bishara, Paul Damon, Jane R. Jakobsen. (1997). Comparison
of shear bond strength and surface structure between conventional acid etching and
air-abrasion of human enamel. Am J Orthod Dentofacial Orthop, 112: 502–506

5. Stenyo Wanderley, Tavares, Simonides, ConsaniII; Darcy Flávio, NouerI; Maria
Beatriz Borges de Araújo, MagnaniI; Paulo Roberto Aranha, NouerIII; Laura Moura,
MartinsIII (2006). Shear bond strength of new and recycled brackets to enamel. Braz
Dent J 17(1): 44-48

6. Şenay Canay, İlken Kocadereli, Ela Akça. (2000). The effect of enamel air abrasion
on the retention of bonded metallic orthodontic brackets Am J Orthod Dentofacial
Orthop 117(1): 15–19

7. W Carstensen. (1995) Effect of reduction of phosphoric acid concentration on the
shear bond strength of brackets. Am J Orthod Dentofacial Orthop, 108: 274–277

8. Wei Nan Wang, Chung Hsing Li, Ta Hsiung Chou, Dennis Ding Hwa Wang, Li
Hsiang Lin, Che Tong Lin. (2004). Bond strength of various bracket base designs.
Am J Orthod Dentofacial Orthop 125(1): 65–70

9. Mark J. Webster, Ram S. Nanda, Manville G. Duncanson Jr, Sharukh S. Khajotia,
Pramod K. Sinha. (2001). The effect of saliva on shear bond strengths of hydrophilic
bonding systems. Am J Orthod Dentofacial Orthop119(1): 54–58

10. Samir E. Bishara, Manal M. A. Soliman, Charuphan Oonsombat, John F. Laffoon,
and Raed Ajlouni. (2004). The Effect of Variation in Mesh-Base Design on the Shear
Bond Strength of Orthodontic Brackets. The Angle Orthodontist 74(3): 400-404.

36

11. Jeremy Knox, Pierre Hubsch, Malcolm L. and John Middleton. (2000). The Influence
of Bracket Base Design on the Strength of the Bracket–Cement Interface. J of Ortho
27(3): 249-254

12. Shane Schaneveldt, Timothy F. Foley. (2002). Bond strength comparison of moisture-
insensitive primers. Am J Orthod Dentofacial 122(3): 267–273

13. Douglas Rix, Timothy F. Foley, Antonios Mamandras. (2001). Comparison of bond
strength of three adhesives: Composite resin, hybrid GIC, and glass-filled GIC
Am J Orthod Dentofacial Orthop 119(1): 36–42

14. Samir E. Bishara, Marc E. Olsen, Paul Damon c, Jane R. Jakobsen. (1998) Evaluation
of a new light-cured orthodontic bonding adhesive. Am J Orthod Dentofacial Orthop
114(1): 80–87

15. Bor-Shiunn Lee, Tseng-Ting Hsieh, Yuan-Ling Lee, Wan-Hong Lan, Yao-Jeng Hsu,
Ping-Han Wen, and Chun-Pin Lin. (2003). Bond Strengths of Orthodontic Bracket
After Acid-Etched, Er:YAG Laser-Irradiated and Combined Treatment on Enamel
Surface. The Angle Orthodontist 73(5): 565-570.

16. Samir E. Bishara, Leigh VonWald, John F. Laffoon, John J. Warren. (2001). Effect of
a self-etch primer/adhesive on the shear bond strength of orthodontic brackets. Am J
Orthod Dentofacial 119(6): 621–624

17. Irene L Zeppieri, Chun-Hsi Chung, Francis K Mante. (2003). Effect of saliva on shear
bond strength of an orthodontic adhesive used with moisture-insensitive and self-
etching primers. Am J Orthod Dentofacial 124(4): 414–419

18. Marvi Talpura, Susan J. Cunninghamb, David R. Moles, and Steven P. Jonesd. (2012)
The relationship between base dimensions, force to failure, and shear bond strengths
of bondable molar tubes. Angle Orthodontist 82(3)

19. Rodney G. Northrupa, David W. Berzinsb, Thomas Gerard Bradleyc, and William
Schuckitd. (2007). Shear Bond Strength Comparison between Two Orthodontic
Adhesives and Self-Ligating and Conventional Brackets. The Angle Orthodontist
77(4):701-706.

20. Petra Schmage, Ibrahim Nergiza, Wolfram Herrmann, Mutlu Özcan. (2003).
Influence of various surface-conditioning methods on the bond strength of metal
brackets to ceramic surfaces. Am J Orthod Dentofacial 123(5):540–546

21. Benjamin R. Nemetha, William A. Wiltshireb, Christopher L.B. Lavellec. (2006).
Shear/peel bond strength of orthodontic attachments to moist and dry enamel. Am J
Orthod Dentofacial 129(3): 396–401

37

22. G.V. Newman. (1964). Bonding Plastic Orthodontic Attachments to Tooth Enamel
J. New Jersey D. Soc 35: 346

23. Zachrisson, B. U. (1997). Cause and prevention of injuries to teeth and supporting
structures during orthodontic treatment. Am J Orthod 69: 285–300

24. Maijer, R. and D. C. Smith. (1981). Variables influencing the bond strength of metal
orthodontic bracket bases. Am J Orthod 79:20–34

25. Retief, D. H. (1974). Failure at the dental adhesive-etched enamel interface. J Oral
Rehabil 1:265–284

26. Knoll, M., A. J. Gwinnett, and M.S. Wolff. (1986). Shear strength of brackets bonded
to anterior and posterior teeth. Am J Orthod 89:476–479

27. Zachrisson, B. U. (1977) A post-treatment evaluation of direct bonding in
orthodontics. Am J Orthod 71:133–189

28. Banks, P. and T. V. Macfarlane. (2007). Bonded versus banded first molar
attachments: a randomized controlled clinical trial. J Orthod 34:128–136

29. M Buonocore. (1955). A simple method of increasing the adhesion of acrylic filling
materials to enamel surfaces J Dent Res. 34: 849–853

30. J Britton, P McInnes, R Weinberg, W Ledoux. (1990). Shear bond strength of
ceramic orthodontic brackets to enamel Am J Orthod Dentofac 98: 348–353

31. Soetopo, DR Beech, JL Hardwick. (1978). Mechanism of adhesion of polymers of
acid-etched enamel. J Oral Rehabil, 5: 69–80

32. Mardaga WJ, Shannon IL. (1982). Decreasing the depth of etch for direct bonding in
orthodontics. J Clin Orthod 16:130-2

33. Retief DH, Harris, BE, Bradley EL, Denys FR. (1985). Pyruvic acid as an etching
agent in clinical dentistry. J Biomed Mater Res 19: 335-48

34. L.R. Legler, D.H. Retief, E.L. Bradley. (1990). Effects of phosphoric acid
concentration and etch duration on enamel depth of etch: An in vitro study.
Am J Orthod 98(2):154–160

35. Samir E. Bishara Leigh VonWald, John F. Laffoon, and John J. Warren. (2000). The
Effect of Repeated Bonding on the Shear Bond Strength of a Composite Resin
Orthodontic Adhesive Angle Orthodontist.70(6)

36. G Christensen. (1991). Dental cements: are they the weak link? J Am Dent Assoc,
122: 63–64
38

37. R Kiockowski, E Davis, R Joynt, G Wieczkowski Jr, A MacDonald. (1989). Bond
strength and durability of glass ionomer cements used as bonding agents in the
placement of orthodontic brackets. Am J Orthod Dentofac Orthop, 96: 60–64

38. A Compton, CE Meyers Jr, S Hondrum, L Lorton. (1992). Comparison of the shear
bond strength of a light-cured glass ionomer and a chemically cured glass ionomer for
use as an orthodontic bonding agent. Am J Orthod Dentofac Orthop, 101: 138–144

39. WA. Wiltshire. (1994). Shear bond strengths of a glass ionomer for direct bonding in
orthodontics. Am J Orthod Dentofacial Orthop 106: 127–130

40. JAM Miguel, MA Almeida, O. Chevitarese. (1995). Clinical comparison between a
glass ionomer cement and a composite for direct bonding of orthodontic brackets
Am J Orthod Dentofacial Orthop 107: 484–487

41. W McLean, JW Nicholson, AD. Wilson. (1994). Proposed nomenclature for glass-
ionomer dental cements and related materials. Quint Int 25: 587–589

42. Tavas, A. and D. C. Watts. (1979). Bonding of orthodontic brackets by
transillumination of a light-activated composite: an in vitro study. Br J Orthod 16:
207–208

43. S. E. Owens Jr and B. H. Miller (2000) A Comparison of Shear Bond Strengths of
Three Visible Light-Cured Orthodontic Adhesives. The Angle Orthodontist 70(5):
352-356

44. Rod Greenlaw, David C Way, Khadry A Galil. (1989). An in vitro evaluation of a
visible light-cured resin as an alternative to conventional resin bonding systems. Am J
Orthod Dentofacial Orthop 96(3): 214–22

45. Simona Tecco, Tonino Traini, Sergio Caputi, Felice Festa, Valentina de Luca, and
Michele D'Attilio (2005) A New One-Step Dental Flowable Composite for
Orthodontic Use: An In Vitro Bond Strength Study. The Angle Orthodontist 75(4):
672-677

46. M. Buonocore. (1970). Adhesive sealing of pits and fissures for caries prevention,
with use of ultraviolet light. J Am Dent Assoc 80: 324–330

47. MG Buonocore, J. Davila. (1973). Restoration of fractured anterior teeth with
ultraviolet-light-polymerized bonding materials: a new technique. J Am Dent Assoc
86:1 349–1354

39

48. Maria Francesca Sfondrini, Vittorio Cacciafesta, Angela Pistorio, Giuseppe Sfondrini.
(2001). Effects of conventional and high-intensity light-curing on enamel shear bond
strength of composite resin and resin-modified glass-ionomer. Am J Orthod
Dentofacial Orthop 119(1): Pages 30–35

49. R Tirtha, PL Fan, JB Dennison, JM. Powers. (1982). In vitro depth of cure of photo-
activated composites. J Dent Res 61: 1184–1187

50. Paul C.L Tsaia, Ian A Meyers, Laurence J Walsh. (2004) Depth of cure and surface
microhardness of composite resin cured with blue LED curing lights. Dental
Materials. 20(4): 364–369

51. K. Fujibayashi, K. Ishimaru, N. Takahashi, A. Kohno. (1998). Newly developed
curing unit using blue light-emitting diodes. Dent Jpn 34: 49–53

52. W.R. Proffit. (2007). Contemporary orthodontics (4th ed.), Mosby, St Louis: 167–233

53. A.L. Sonis. (1996). Air abrasion of failed bonded metal brackets: a study of shear
bond strength and surface characteristics as determined by scanning electron
microscopy. Am J Orthod Dentofacial Orthop, 110: 96–98

54. Millet D, Mccabe JF, Gordon PH. (1993). The role of sandblasting on the retention of
metallic brackets applied with glass ionomer cement. Br J Orthod 201: 117-122

55. G.H Hanson, W.M Gibbon, H Shimizu. (1983) Bonding bases coated with porous
metal powder: a comparison with foil mesh Am J Orthod, 83:1–4

56. Farzaneh Ahrari, Mohammad Basafa, Reza Fekrazad, Mohammad Mokarram, and
Majid Akbari. (2012) The Efficacy of Er,Cr:YSGG Laser in Reconditioning of
Metallic Orthodontic Brackets. Photomedicine and Laser Surgery 30(1): 41-46

57. Ishida, K., Endo, T., Shinkai, K., and Katoh, Y. (2011). Shear bond strength of
rebonded brackets after removal of adhesives with Er,Cr:YSGG laser. Odontology
99: 129–134

58. BU Zachrisson, T Büyüky¦lmaz. (1993). Recent advances in bonding to gold,
amalgam and porcelain. J Clin Orthod, 27: 661–675

59. BU Zachrisson. (1994). Bonding in orthodontics. TM Graber, RL Vanarsdall,
Orthodontics: current principles and techniques: Mosby, St Louis: 542–626

60. D Millett, JF McCabe, PH Gordon. (1993). The role of sandblasting on the retention
of metallic brackets applied with glass ionomer cement. Br J Orthod, 20: 117–122

40

61. Manuela M. Haro Montero, Ascensión Vicente, Noelia Alfonso-Hernández, Manuel
Jiménez-López, and Luis-Alberto Bravo-González (2014) Comparison of shear bond
strength of brackets recycled using micro sandblasting and industrial methods. The
Angle Orthodontist In-Press.

62. S. Sunna, W. P. Rock. (2014) Effect of sandblasting on the retention of orthodontic
brackets: a controlled clinical trial. Journal of Orthodontics 35:1, 43-48.

63. Jan Ødegaard, Dietmar Segner. (1988). Shear bond strength of metal brackets
compared with a new ceramic bracket. Am J Orthod Dentofacial Orthop. 94(3): 201–
206

64. J. W. Ferguson , M. J. F. Read , D. C.,Watts. (1984). Bond strengths of an integral
bracket-base combination: an in vitro study European Journal of Orthodontics 6:
1984

65. Miller SL. (1981). Introductory statistics for dentistry and medicine. Reston: Prentice-
Hall

66. Robert N. Moore, Michael D. Bagby, Joseph M. Bordeaux. (1994). Comparative
evaluation of ceramic bracket base designs. Am J Orthod Dentofacial Orthop 105(6):
552–560

67. Instron Corp. (2013). Grove City, PA. 6960 SeriesDual Column Tabletop (6) 0113

68. Arndt Klocke, Bärbel Kahl-Nieke. (2005). Influence of force location in orthodontic
shear bond strength testing. Dental Materials 21(5): 391–396

69. T.R. Katona. (1997). A comparison of the stresses developed in tension, shear peel,
and torsion strength testing of direct bonded orthodontic brackets. Am J Orthod
Dentofacial Orthop 112: 244–251

70. I.R. Reynolds. (1975). A review of direct orthodontic bonding Br J Orthod, 2 : 171–
178

71. Mehmet Oğuz Öztopraka, Fulya Isikb, Korkmaz Sayınsub, Tulin Arunc, Bulent
Aydemira.(2007). Effect of blood and saliva contamination on shear bond strength of
brackets bonded with 4 adhesives. Am J Orthod Dentofacial Orthop 131(2): 238–242

72. Assure Bonding Resin, Reliance Orthodontic Products. Inc., Itasca, IL. (2008).
Material Safety Data Sheet.

73. Lang, BR, Jaarda, M, Wang, RF. (1992) Filler particle size and composite resin
classification systems. J Oral Rehabil 19(6): 569-84

41

74. Masahiro Iijimaa, Takeshi Mugurumab, William A. Brantleyc, Toshihiro Yuasab, Jun
Uechib, Itaru Mizoguchid. (2010) Effect of mechanical properties of fillers on the
grindability of composite resin adhesives. Am J Orthod Dentofacial Orthop 138(4):
420–426

75. Paola Cozza, Leonardo Martucci, Laura De Toffol, and Santiago Isaza Penco (2006)
Shear Bond Strength of Metal Brackets on Enamel. The Angle Orthodontist 76(5):
851-856

76. Kevin L. Pickett, P. Lionel Sadowsky, Alex Jacobson, and William Lacefield (2001)
Orthodontic In Vivo Bond Strength: Comparison with In Vitro Results. The Angle
Orthodontist 71(2): 141-148

Abstract (if available)

Abstract Objective: The purpose of this study is to compare the shear bond strengths of standard single mesh, sandblasted and laser‐etched orthodontic bracket bases. Our H₀ hypothesis is there is no difference in shear bond strength of standard single mesh, sandblasted brackets and laser‐etched orthodontic bracket bases. ❧ Methods: To compare bond strength of commercially available orthodontic brackets thirty‐six brackets were divided into three equal groups. Single mesh control (n=12), sandblasted bracket bases (n=12), laser‐etched bracket bases (n=12) were bonded to a composite disk and subjected to shear bond strength tests using an Instron Universal Testing Machine. ❧ Results: Shear bond strength (SBS) for all three groups ranged from 12.25 MPa to 34.99 MPa. Control group (single‐mesh) SBS ranged from 16.79 to 30.00 MPa (mean = 24.1072 MPa), sandblasted group ranged from 21.05 to 34.99 MPa (mean =30.8143 MPa) and the laser‐etched group ranged from 12.25 to 29.43 MPa (mean =21.7709 MPa). A one‐way ANOVA with post‐hoc Tukey B for group wise comparison was performed at α=0.05. ❧ Conclusion: In this study, the surface treatment of orthodontic bracket bases using sandblasting resulted in significantly higher shear bond strength compared to standard single mesh and laser‐etched bracket bases. When comparing the shear bond strength of laser‐etched and control mesh bracket bases, there was no significantly different from each other.

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Asset Metadata

Creator Vrontikis, Peter Mark (author)

Core Title Shear bond strength comparison of mesh, sandblasted and laser-etched orthodontic brackets

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 04/21/2015

Defense Date 03/09/2015

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

Tag brackets,laser-etched,mesh,OAI-PMH Harvest,orthodontic,sandblasted,shear bond strength

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Sameshima, Glenn T. (committee chair), Grauer, Dan (committee member), Paine, Michael L. (committee member)

Creator Email peter@vrontikis.com,vrontiki@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-555255

Unique identifier UC11301339

Identifier etd-VrontikisP-3358.pdf (filename),usctheses-c3-555255 (legacy record id)

Legacy Identifier etd-VrontikisP-3358.pdf

Dmrecord 555255

Document Type Thesis

Format application/pdf (imt)

Rights Vrontikis, Peter Mark

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Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

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...

Repository Name University of Southern California Digital Library

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