Download Comparison of Mean Shear Bond Strength of Light Cure, Self

10.5005/jp-journals-10021-1100
ORIGINAL ARTICLE
Chandresh Shukla et al
Comparison of Mean Shear Bond Strength of
Light Cure, Self-Cure Composite Resins,
Self-Etching and Moisture-Insensitive Primers:
An in vitro Study
1
Chandresh Shukla, 2Gurmukh Singh, 3Upendra Jain, 4Karthik Swamy
ABSTRACT
Objectives: This study was aimed to compare the mean shear bond strength of four orthodontic bonding materials used for bonding orthodontic
brackets. Self-cure composite adhesive (Reliance orthodontics), light cure composite adhesive (Transbond XT, 3M Unitek), light cure with
self-etching primer (SEP), Transbond XT and Transbond Plus, 3M Unitek and light cure with moisture-insensitive primer (MIP) (Transbond XT and
Transbond MIP) were used.
Materials and methods: One hundred and twenty maxillary premolar teeth were collected and divided into four groups. Thirty separate maxillary
premolar brackets were bonded to the teeth for each of the bonding agents. Debonding were carried out by using Instron universal testing machine.
Results: Light cure composite adhesive (Transbond XT, 3M Unitek) had the highest shear bond strength followed by light cure and SEP (Transbond
Plus and Transbond XT, 3M Unitek) followed by light cure and MIP (Transbond MIP and Transbond XT, 3M Unitek) and the lowest was self-cure
composite adhesive (Rely-a-bond, Reliance orthodontics).
Conclusion: All the materials had the minimal shear bond strength required for orthodontic bonding as proposed by Reynolds and they can be
used clinically.
Keywords: Shear bond strength, Self-etching primer, Moisture-insensitive primer.
How to cite this article: Shukla C, Singh G, Jain U, Swamy K. Comparison of Mean Shear Bond Strength of Light Cure, Self-Cure Composite
Resins, Self-Etching and Moisture-Insensitive Primers: An in vitro Study. J Ind Orthod Soc 2012;46(4):254-257.
INTRODUCTION
In the evolution of fixed orthodontic appliances, esthetic is
one of the prime concern in the acceptance of any appliance
by the patient. This time consuming and unesthetic procedure
has been virtually discarded after the introduction of acid-etch
direct bonding technique in 1955 by Buonocore.1 First bonding
of orthodontics bracket was reported by Newman2 in 1965.
Over the past 2 decades, the evolution of adhesive techniques
has transformed the scope of dental practice. The development
of light cured composite has become increasingly popular for
bonding orthodontic attachment. The unlimited working time
of the adhesive allows the orthodontist to manipulate the
1
Senior Lecturer, 2Professor and Head, 3Professor, 4Reader
1-4
Department of Orthodontics and Dentofacial Orthopedics
People’s College of Dental Sciences and Research Centre, Bhopal
Madhya Pradesh, India
Corresponding Author: Chandresh Shukla, Senior Lecturer
Department of Orthodontics and Dentofacial Orthopedics, People’s
College of Dental Sciences and Research Centre, Bhopal
Madhya Pradesh, India, e-mail: [email protected]
Received on: 22/10/11
Accepted after Revision: 5/4/12
254
bracket position until polymerization is initiated by visible
light source.3
Bis-GMA or Bowen’s resin, which is a self-cure resin,
provides good bond strength, but has few inherent flaws. It is
extremely technique sensitive. Having a short setting time, it
permitted limited working time for accurate bracket
positioning.4
The sixth generation self-etching primer system [selfetching primer (SEP)] consists of etchant and primer
dispersed as a single unit. Hence, the etching and priming are
merged as a single-step stage in bonding procedure, resulting
in time saving for the clinician, which has cost implications.4
Seventh generation bonding agent [moisture-insensitive
primer (MIP)] is the latest entrant and the first no mix bonding
adhesive which sets in presence of moisture giving effective
bond strength. This is totally insensitive to moisture.
Moisture-free oral environment during bonding is often
difficult to achieve clinically.5
AIMS AND OBJECTIVES
The aim of this study was to compare the shear bond strength
of orthodontic brackets bonded with a self-cure bonding
material (Rely-a-Bond), light cure bonding material
(Transbond XT) and sixth generation SEP system (Transbond
Plus) and seventh generation MIP system (Transbond MIP).
JAYPEE
JIOS
Comparison of Mean Shear Bond Strength of Light Cure, Self-Cure Composite Resins
MATERIALS AND METHODS
Total 120 extracted human maxillary permanent premolars
were collected; the teeth were rinsed with water to clean blood
and soft tissue debris and then decontaminated with 0.5%
thymol. Further, the teeth were stored in distilled water at 37°C
for 2 weeks. Each tooth was placed in a mould and roots were
embedded in self-curing acrylic resin block (diameter = 15
mm; height = 20 mm) up to 1 mm apical to CE junction. The
long axis of the tooth was kept parallel to the long axis of the
acrylic block. Crowns were kept exposed to facilitate surface
treatment and adhesive bonding on buccal surfaces. The acrylic
resin blocks were color-coded to differentiate four groups of
30 teeth as follows.
1. Group A: Teeth were embedded in green-colored acrylic
resin blocks for bonding using self-cure resin (Rely-a-bond,
Reliance orthodontics products, Itasca.III; Fig. 1).
2. Group B: Teeth were embedded in pink-colored acrylic
resin blocks for bonding using light cure composite
(Transbond XT, 3M Unitek, Monrovia, Calif; Fig. 2).
3. Group C: Teeth were embedded in yellow-colored acrylic
resin blocks for bonding using self-etching primer (SEP)
and light cure composite (Transbond Plus and Transbond
XT, 3M Unitek, Monrovia, Calif; Fig. 3).
4. Group D: Teeth were embedded in black-colored acrylic
resin blocks for bonding using MIP and light cure composite
(Transbond MIP and Transbond XT, 3M Unitek, Monrovia,
Calif; Fig. 4).
Orthodontic preadjusted edgewise appliances (PEA) metal
brackets having 0.022 × 0.028 MBT slot for maxillary premolar
(Gemini 3M, Unitek Monorovia, Calif) were used for bonding.
The surface area of bracket was 10.61 mm2. All the brackets
were bonded on the buccal surfaces according to the instructions
supplied by the manufacturer. All bracket were bonded by a single
operator to avoid interoperator variation (Figs 5A to D).
The shear bond strength tests were done using Instron
universal testing machine no.3382 at cross head speed of
1 mm/min force passing parallel to buccal surface (Fig. 6). A
custom-made rod was locally fabricated for debonding of
brackets (Fig. 7). Each block was fixed in a metal jig a force
parallel to the tooth surface in an occlusal-apical direction
was applied by the machine. The force required to debond each
bracket was registered in newtons and converted into
megapascals by using the following formula:
Bond strength MPa = force in Newtons/surface area of
bracket in mm2.
Fig. 1: Self-cure composite (Rely-a-Bond, Reliance orthodontic
products, Itasca.III)
Fig. 3: Transbond Plus self-etching primer and Transbond XT
adhesive (3M Unitek, Monrovia, California)
Fig. 2: A 37% phosphoric acid and Transbond XT light cure primer and
adhesive (3M Unitek, Monrovia, California)
Fig. 4: MIP and light cure composite
(3M Unitek, Monrovia, California)
The Journal of Indian Orthodontic Society, October-December 2012;46(4):254-257
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Chandresh Shukla et al
Figs 5A to D: Individual block showing buccal, mesial, distal and occlusal view of the bracket bonded to buccal surface
Statistical Analysis
Mean shear bond strength (SBS) of different groups was
determined using student’s t-test. The level of significance
(p-value) was kept at 0.05.
RESULTS
Fig. 6: Instron universal testing machine no. 3382
Group A (self-cure composite resin) showed a mean SBS of
9.03 ± 1.14 and group B (light cure composite resin) showed
a mean SBS of 10.34 ± 2.91 and group C (light cure and SEP)
was showing mean SBS of 9.78 ± 0.871 and group D (light
cure and MIP) showed a mean SBS of 9.65 ± 0.90. The
difference between self-cure and light cure composite resin
and self-cure and light cure with SEP and self-cure and light
cure and MIP was statistically significant (S). On the other
hand, in comparison of light cure composite resin and light
cure with SEP and light cure composite resin and light cure
and MIP was statistically nonsignificant (NS), the difference
between light cure and MIP and light cure with SEP was
nonsignificant (NS) as confirmed by paired t-test (Table 1).
DISCUSSION
The findings of this study indicated that in all the three groups,
the mean SBS to the tooth was highest with group B light cure
composite resin (10.34 ± 2.91 MPa) followed by group C light
cure and SEP (9.78 ± 0.871 MPa) and the lowest for group A
self-cure composite resin (9.03 ± 1.14). The groups A
Fig. 7: Metal zig with push rod
Table 1: Comparison of SBS between all the groups
Groups
A and B (self-cure and light cure composites)
B and C (light cure and light cure + SEP)
B and D (light cure and light cure + MIP)
A and C (self-cure and light cure + SEP)
A and D (self-cure and light cure + MIP)
C and D (light cure + SEP and light cure + MIP)
Mean (SBS ± SD) in MPa
9.03 ± 1.14
10.34 ± 2.91
10.34 ± 2.91
9.78 ± 0.87
10.34 ± 2.91
9.65 ± 0.90
9.03 ± 1.14
9.78 ± 0.87
9.03 ± 1.14
9.65 ± 0.90
9.78 ± 0.87
9.65 ± 0.90
t-value
p-value
Significant (S)/
nonsignificant (NS)
2.01
0.01
S
0.95
0.34
NS
0.95
0.24
NS
2.68
0.012
S
2.43
0.021
S
0.50
0.61
NS
S: Significant; NS: Nonsignificant
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Comparison of Mean Shear Bond Strength of Light Cure, Self-Cure Composite Resins
(self-cure composite resin) and B (light cure composite resin)
were showing significant differences in their SBS and p-value
is 0.01 as similar with the study done by O’Brien KD and Read
MJF,6 they concluded that light cure is having low bond failure.
Wang et al7 also got the same result but they suggested that
light cure may be less, if there is less visible light exposure
and, self-cure may be less, if there is air bubble during mixing.
Chamada et al8 suggested that light cure is better, if it is cured
for 2 to 5 minutes. Viazia et al9 suggested that there is no
significant difference between both the adhesives, if they are
used for ceramic bracket bonding. Warren Hamula10 got similar
results as in the present study. They also concluded that light
cure composites are better. Clinically, self-cure composites
have limited working time during bonding but light cure
composites are fully operator controlled.
Group A (self-cure composite resin) and group C (light
cure and SEP) were showing significant difference in their
SBS. The p-value were 0.012 and group C was having more
SBS than group A but study done by Yasser Lotfy Abdelnabya11
has shown insignificant difference between both the groups
but the significant result of the present study may be because
of group A was exposed to light and self-cure was not exposed
as it is chemically activated but there is not many studies are
present and still research is going on for these materials.
Groups B (light cure composite) and C (light cure and SEP)
were showing nonsignificant difference in their SBS. The
p-value was 0.34 and group B was having more SBS than group
C. The result was similar to studies done by Bishara et al,12
Hanning M et al.13 This was probably because phosphoric acid
etching produces rough etched enamel surfaces. Bonding
brackets to such a surface results in thick and uniform resin
tags that deeply penetrate the enamel. On the other hand,
shallower and fewer resin tags are obtained with SEP system.14
Groups A (self-cure composite resin) and D (light cure
and MIP) were showing significant difference in their shear
bond strength. The p-value was 0.021. In a similar study, done
by Miller et al,15 they found insignificant differences in the
shear bond strength between the same groups.
Groups B (light cure composite) and D (light cure and
MIP) showed nonsignificant difference in their SBS. The
p-value was 0.24. The result was similar to studies done by
Schaneveldt16 and Zeppieri IL et al.17
Groups C (light cure and SEP) and D (light cure and MIP)
showed nonsignificant difference in their SBS. The p-value
was 0.61. The result was same to studies done by Schaneveldt16
and Zeppieri IL et al.17 They also found that the bond strength
of SEP was more than MIP, this may be because of moisture
contamination as contaminated surface can reduce the bond
strength.
CONCLUSION
Based on the recorded data from the present study, following
conclusions may be drawn:
1. Light cure composite adhesive (Transbond XT, 3M Unitek,
Monrovia, Calif) had the highest SBS followed by light
cure and SEP (Transbond Plus and Transbond XT, 3M
Unitek, Monrovia, Calif) followed by light cure and MIP
(Transbond MIP and Transbond XT, 3M Unitek, Monrovia,
Calif) and the lowest was self-cure composite adhesive
(Rely-a-bond, Reliance orthodontic products, Itasca.III).
2. In the present study, the entire four different bonding
agents have shown SBS value of more than 7.8 MPa, hence,
all the four materials are suitable for clinical use.
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